United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
EPA-600 2-78-216
December 1978
Research and Development
&EPA
Overview of the
Fresh Pack Food
Industries
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping'was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution-sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-78-216
December 1978
OVERVIEW OF THE FRESH PACK FOOD INDUSTRIES
by
Laszlo P. Somogyi
Peter E. Kyle
SRI International
Menlo Park, California 9^025
Grant Wo. R80.1|6U2-D1
Project Officer
Kenneth Dostal
Food and Wood Products Branch
Industrial Environmental Research Laboratory
Cincinnati, Ohio ^5268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO if5268
-------
DISCLAIMER
This report has been reviewed by the Industrial Environmental Research
Laboratory, U. S. Environmental Protection Agency, and approved for publi-
cation. Approval does not signify that the contents necessarily reflect
the vievs and policies of the U. S. Environmental Protection Agency, nor
does mention of trade names of commercial products constitute endorsement or
recommendation for use.
ii
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FOREWORD
When energy and material resources are extracted, processed, converted,
and used, the related pollutional impacts on our environment and even on
our health often require that new and increasingly more efficient pollution
control methods be used. The Industrial Environmental Research Laboratory-
Cincinnati (lERL-Ci) assists in developing and demonstrating new and improved
methodologies that will meet these needs both efficiently and economicallyi
The report reviews the pollution generated during the market preparation
of fresh fruits, vegetables, fish and shell eggs. Ten of the largest volume
crops of fruit and begetables are discussed. For each commodity the unit
operations are described along with the extent of water usage and emission
sources. For further information, contact the Food and Wood Products Branch
of lERL-Ci.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
iii
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ABSTRACT
Pollution sources generated during the market preparation of fresh
fruits, vegetables, fish and shell eggs were assessed. From the over
one hundred different fruits and vegetables that are grown commercially
in the United States, ten of the largest volume crops were selected for
this study representing over 70 percent of the total volume. In addi-
tion, because of the specificity of their handling requirements, two nut
crops, two species of fresh fish and fresh eggs were also included in
this study. The method of approach used in conducting the study was to
prepare descriptions on unit operations for each crop and to identify
the extent of water usage, sources of effluent and emission from each
step from harvest to shipment to market.
This report was submitted in fulfillment of Grant No. R 804642-01
by SRI International under the sponsorship of the U.S. Environmental
Protection Agency. This report covers the period 1 June 1977 to 28 April
1978 and was completed as of 28 April 1978.
IV
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CONTENTS
Foreword iii
Abstract iv
Figures viii
Tables ix
1. Introduction 1
2. Summary and Conclusions 2
3. Background 6
U. Method of Approach 7
Common unit operations 7
Preparing fresh produce for market 13
Trimming 13
Field packs 13
Washing 13
Dumping the field containers 1^
Fumigation Ik
Vapor-heat treatment 15
Cold treatment 16
Coating 16
Grading 17
5- Results and Discussion of Pollution Problems in the
Fresh Produce Industry ' 19
Air pollution 19
Solid wastes 21
Water pollution 21
Pesticides and chemical processing aids 2U
6. Apples 26
General industry characteristics 26
Unit processing operations 27
-------
7. Grapes .......................... 31
General industry characteristics
Unit processing operations
8. Tree Nuts
Almonds .......................... 3
General industry characteristics ........... 3^
Unit processing operations .............. 3^
Walnuts .......................... 37
General industry characteristics ........... 37
Unit processing operations .............. 37
9. Citrus Fruits
General industry characteristics ............. ^3
Oranges ....................... ^3
Grapefruit ...................... ^6
Lemons ........................ ^7
Unit Processing Operations ................ ^T
Picking ....................... ^7
Handling ....................... 51
Accelerated coloring or sweating ........... 52
Precooling ...................... 53
Storage ....................... 5^
10. Celery .......................... 59
General industry characteristics ............. 59
Unit processing operations ................ 60
11. Lettuce .......................... 62
General industry characteristics ............. 62
Unit processing operations ................
12. Melons
Florida watermelons 65
General industry characteristics 65
Unit processing operations 65
California cantaloupes 67
General industry characteristics 67
Unit processing operations , 67
13. Onions 69
General industry characteristics 69
Unit processing operations 69
VI
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Ik. Potatoes 73
General industry characteristics 73
Unit processing operations 7^
15. Shell Eggs 78
General industry characteristics 78
Unit processing operations 80
16. Fresh Fish 85
General industry characteristics 85
Halibut 85
Salmon 86
Unit processing operations 88
Quality maintenance . 88
Salt-water icing 90
Use of preservatives for treatmrnt of chilled fish . . 90
Boxing at sea 91
Shore plant procedure and marketing 91
Packaging 91
Storage 93
Oysters
no
General industry characteristics "-1
Unit processing operations 94
References and Bibliography 97
Fresh fruit and vegetables 97
Fresh fish 99
Fresh eggs 100
vii
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FIGURES
Number Page
1 Distribution of Almonds 1973-74 , 35
2 Distribution of Walnuts 1973-74 38
3 Distribution of Walnuts 1973-74 1+lj.
4 Approximate Commercial Shipping Seasons for
Florida Citrus Fruits .... ^8
5 Approximate Commercial Shipping Seasons for
California and Arizona Citrus Fruits ...,,... ^9
6 Approximate Commercial Shipping Seasons for
Texas Citrus Fruits , . . . 50
7 Egg Marketing Channels 79
8 Shell Egg Process Flow Diagram 8l
9 Marketing Flow Diagram for Fresh Salmon ....... 87
10 Marketing Flow Diagram for Frozen Salmon 88
viii
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TABLES
Mmiiber Page
1 Estimated Annual Water Requirement for the Fresh Market ~~
Preparation of Selected Fruits and Vegetables ......
2 Recommended Temperatures for the Transport and
Short-Term Storage of Fruit and Vegetable Products ... to
3 Recommended Temperature and Relative Humidity,
Approximate Storage Life, Highest Freezing Point, Water
Content, and Specific Heat of Fresh Fruits and Vegetables
in Commercial Storage .................. 11
4 Major Sources of Solid Wastes Generated in Fresh Produce
Handling and Their Utilization ............. 22
5 Estimated Quantities of Solid Wastes from Food Industry
in California, 1967 ................... 23
6 Water Use by the Fresh Fruit, Vegetable, Egg and Fish
Handling Industries ................... 2U
7 Carbon Dioxide, Oxygen, and Temperature Requirements for
Controlled Atmosphere Storage of Apples Grown in the
United States ...................... 29
8 Contribution of Apple Industry Unit Operations to
Pollution ........................ 30
9 Contribution of Grape Industry Unit Operations to
Pollution ........................ 33
10 Contribution of Tree Nut Industry Unit Operations to
Pollution ........................ 4l
11 Contribution of Citrus Industry Unit Operations to
Pollution ........................ 57
12 Planting and Harvesting Dates for Celery ........ 59
13 Contribution of Celery Industry Unit Operations to
Pollution ........................ 61
14 Planting and Harvesting Dates for Lettuce ....... . 63
15 Contribution of Lettuce Industry Unit Operations to
Pollution ........................ 6k
16 Planting and Harvesting Dates for Watermelon ...... 66
17 Contribution of Watermelon and Cantaloupe Industry to
Pollution ........................ 68
ix
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Number
18 Contribution of Onion Industry Unit Operations to
Pollution
19 Planting and Harvesting Dates for Potatoes ....... 7^
20 Contribution of Potato Industry Unit Operations to
Pollution ........................ T7
21 Contribution of Shell Egg Industry Unit Operations to
Pollution ........................ °3
22 Contribution of Oyster Industry Unit Operations to
Pollution ........................ 96
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SECTION 1
INTRODUCTION
The fresh produce industry is a major segment of the food industry
in terms of volume marketed, number of establishments, and wash loads
generated. All fruits and vegetables are processed to some extent
before being displayed to consumers as fresh produce. Sometimes these
operations are done in the field, such as curing (onions), trimming, or
topping (lettuce, celery). Size-grading and packaging are usually done
in packing sheds near the growing sites. However, several fruit and
vegetable crops require more than these simple processing procedures.
Some produce requires special treatment, such as air cooling or hydro-
cooling (lettuce), postharvest fumigation (grapes), or ripening treat-
ment under a controlled atmosphere (lemons) to extend their shelf life.
Others are treated with coating substances (oranges, apples, cantaloupes)
and food coloring (oranges in Florida) to improve their visual appeal
and shelf life and thus enhance their market value. In such instances,
further processing is usually done in central plants whose sole function
is fresh commodity production; occasionally it is done in conjunction
with a canning and/or freezing operation.
Within this industry, no EPA studies have been conducted to describe
the industry and the associated pollution problems. In this study we
present data on the size of the industry and review the environmental
problems associated with the market preparation of 15 selected important
commodities. The ten selected fruit and vegetable commodities represent
more than 70 percent of the total volume of that industry, based on 1975
government statistics. Walnut and almond represent 71.4 percent of the
nut crops. In addition shell-eggs and two-species of fresh fish were
included in this study.
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SECTION 2
SUMMARY AND CONCLUSIONS
Market preparation of most fresh fruits, vegetables, fish, and shell
eggs requires substantial use of water and generates organic wastes.
Although more than one hundred different fruits and vegetables are grown
commercially in the United States, ten of the largest volume crops
represent over 70 percent of the total volume. To assess the contribu-
tion of the fresh produce handling industry, to pollution problems, we
have reviewed the common unit operations applied following harvest and
the water usage and waste disposal associated with the ten highest
volume crops. Because of the specificity of their handling requirements,
we also included two nut crops, two species of fresh fish, and fresh
eggs in this investigation.
From this analysis, we have made the following conclusions about
the fresh produce handling industries:
• The industries are not a major source of air pollutants.
Gaseous compounds such as ethylene, carbon dioxide are
applied at low concentrations (0.1 and 1-8 percent level
respectively), therefore they do not measurably change the
air composition of the surrounding area. Sulphur dioxide
used for grape fumigation is applied in enclosed storage
area at a 2 percent concentration. Some operations are
sources of unpleasant odors, but they create only local
anm^ance. Most of them, such as onion and garlic curing, are
seasonal operations and are located some distance from densely
populated areas. Malodors from egg-washing operations, how-
ever, can create a significant year-round problem and occasionally
have elicited major complaints from nearby communities.
Technology is available to contain and treat the contaminated
egg wash water and to control emission of malodor.
• The industries are major sources of solid wastes comprising
various natural organic substances. However, the quantity of
such wastes is minor when compared to the entire solid wastes
generated by the food processing industry. Large portions
of these wastes are returned to the field, or used as by-
products, fuel, or feed, and only minor portions are handled
in central locations where they occasionally create local
problems when disposed to city sewage systems. The sizeable
wastes from nut shelling are eliminated because they are used
completely as fuel or other by-products.
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• The industries are major users of water, because the market
demands clean produce. Most water is used to clean fresh
produce, and therefore will be contaminated with soil and plant
residues. Besides washing, cleaning water is used for
transporting fruits through grading and inspection systems
(hydro-handling), and for cooling fresh fish, fruits and
vegetables (iceing, hydrocooling).
• The industries are creating large volumes of wastewater with
varying strengths of organic pollutants. Fresh market prepara-
tion of onion, garlic, grapes and lettuce does not require water
use; nuts, melons and celery preparation necessitates only
insignificant use of water, for occasional washing and hydro-
cooling. However, water is used in significant quantities for
the fresh market preparation of apple, citrus fruits, potatoes
and eggs. Data collected in this study indicates the following
water usage for these produce: apples 10,000 gallon/day
(38,230 I/day) for 10,000-20,000 cartons/day production (36
to 44 Ibs or 16.3-20.0 kg each); oranges 850-1050 gallon/hours
(3,217-3,974 liter/hour) producing 1,000-1,200 field boxes/
hour (50-55 Ibs (22.7-25 kg. each); lemon 935-1,235 gallon per
hour (3,539-4,674 liter/hour) producing 1,000-1,200 field
boxes/hour (40 Ibs or 18.2 kg each); potatoes 4.58-10 gallons
(17.3-37.9 liters) per hundred weight (45.4 kg).
Based on these figures water usage was calculated for the
preparation of 1 million pound (4,540 kg) produce and the
annual water usage for each crop was projected (Table 1).
Assuming that waste water is equal to water intake the total
waste generated by the four largest water user crop is less than
2 percent of the waste water flow volume of the canned and
preserved fruit and vegetable industry, which has been
previously estimated at 130 billion gallons per year.
No information was obtained to indicate that hazardous
pollutants are present in wastes discharged from fresh produce
handling facilities.
The wastewater contains some detergent compounds which are
applied in the cleaning processes. Cleaning water and hydro-
cooling water is also frequently'treated with germicides, and
therefore these compounds enter into the waste streams.
Chlorine at concentrations between 2 and 20 ppm is used most
frequently as a germicide. Other compounds primarily applied
to the water in citrus fruit operations include Sodium-o-
phenylphenate (SOPP) at 2-3' ppm level, 1% 2-aminobutene, methyl
bromide, ethylene dibromide and benzimidazole. Surface coating,
coloring (Florida oranges only) and sprout inhibition (potatoes)
compounds are applied after the last washing and therefore they
do not contaminate the waste water. The only exception to this
is the removal of lemon storage waxing compound by washing.
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TABLE 1. ESTIMATED ANNUAL WATER REQUIREMENT FOR THE FRESH MARKET PREPARATION OF
SELECTED FRUITS AND VEGETABLES
(Major crops with high water requirements were selected)
Water requirement for
preparation of 1 million Estimated yearly
Crop pound (U,5^0 kkg) production in U.S. Estimated water use in U.S'.
Gallon Cubic meter Million pound Million kkg Million gallon Thousand cubic'meter
Apple 6,300-2^,000 2h-91 3,865 17-5 2h-9S> 92-369
Orange 18,600-23,000 71-87 3,900 17-7 73-90 275-3^0
Lemon 23,^00-30,900 89-117 839 3.8 20-26 7^-98
Potato 1*5,800-100,000 173-378 15,900 72.2 730-1590 2760-6020
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The wastewater is often disposed on land in the field. Central
packing houses however, frequently discharge to municipal treat-
ment plants. Very little information was obtained on the
effluent quality in terms of COD, BOD, or suspended solids.
Some of the values that were obtained are listed below:
Sunkist orange packing plant COD of effluent from 3420-
(Ontario, California) 3760 mg/1 (discharged into
city sewer)
*
Norco Ranch BOD of effluent 2850-
(Riverside, California) 4000 mg/1 (discharged to a
*(0ne of the largest US egg land application system)
processors with a wastewater
discharge volume of
30,000 gal/day (113,400 1/d)
The industries are not introducing harmful chemicals from
disposal of material containing pesticide residues or other
potentially hazardous chemicals. All chemicals applied by
this industry are carefully screened before their use is
legally permitted. Generally, those substances are used at
very low concentrations that are not likely to create harmful
effects to the environment.
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SECTION 3
BACKGROUND
The significance of the size of the fresh fruits, nuts and
vegetables industry is recognized in that approximately 40 percent of
the total fruit and 46 percent of the total vegetables are consumed in
fresh form.
This study undertaken by SRI International covered 12 commodities
in this industry, representing approximately 70 percent of total fresh
fruit, nut and vegetable consumption in the United States. These
commodities were:
• Vegetables:
- Potatoes, approximately 32.1% of total fresh vegetable
consumption
- Lettuce, approximately 13.5% of total fresh vegetable
consumption
- Onions, approximately 7.1% of total fresh vegetable consumption
- Celery, approximately 4.0% of total fresh vegetable consumption
- Melons, approximately 10.9% of total fresh vegetable consumption
Total: 67.6%
• Fruits:
- Oranges, approximately 24.5% of total fresh fruit consumption
- Grapefruit, approximately 12.9% of total fresh fruit consumption
- Lemons, approximately 3.1% of total fresh fruit consumption
- Grapes, approximately 3.8% of total fresh fruit consumption
- Apples, approximately 27.4% of total fresh fruit consumption
Total: 71.7%
• Nuts:
- Walnuts, approximately 31.8% of the total nut crop
- Almonds, approximately 39.6% of the total nut crop
Total: 71.4%
In addition to the above, fresh eggs and two fresh fish species
were covered by the study.
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SECTION 4
METHOD OF APPROACH
In conducting this study, SRI International gathered data from
three sources:
• A comprehensive literature review of government, trade
association, and industry publications
• Personal interviews with university agricultural extension
staff in Florida, Idaho, Washington, and California
• Field surveys among growers, packing shed operators, grower
cooperatives, and trade associations in Florida, Washington,
and California.
Relevant information gathered from these sources was collated
with selected nonproprietary in-house data at the project team's
disposal, and this information was used to compile a general description
of each industry and the unit processing operations common to each.
COMMON UNIT OPERATIONS
Harvest, transport, storage, and marketing of fruits and vegetables
are the common unit processing procedures requiring the skills and
ingenuity of people in this industry. After vegetables reach harvest
maturity, speedy operations are required by growers, handlers, marketing
specialists, wholesalers, and retailers to move produce from the farm
to the consumers. It is important to recognize that fruits after
harvest continue to carry on most of the life processes that predominated
just before harvest. They respire, and in doing so use up oxygen, give
off carbon dioxide and ethylene, and generate heat. Moisture loss or
transpiration are also continuous. Since moisture content of most fruit
and vegetable is high, this weight loss during transport and storage
can be a serious economic factor.
The principal factors that require attention during the handling
of fresh fruits and vegetables are:
(1) Metabolic changes associated with respiration, ripening, and
aging (composition, texture, color).
(2) Moisture loss, with resultant wilting and shriveling.
(3) Bruising and mechanical injury.
(4) Parasitic diseases.
7
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(5) Physiological disorders.
(6) Freezing and chilling injury.
(7) Flavor changes.
(8) Growth (sprouting, rooting).
Important features of the environment that influence the longevity
of the produce, and that are amenable to control, are temperature,
humidity, and the composition of the atmosphere surrounding the produce.
Low temperatures depress the physiological activity both of the
vegetable tissues themselves and of any micro-organisms capable of
causing spoilage. High humidities reduce loss of water from the tissues
and therefore retard wilting or desiccation, but they may encourage the
germination and growth of organisms on the surfaces. Increases in
carbon dioxide concentration and reduction in oxygen concentration,
whether arising naturally as a result of the respiratory activity of the
products themselves or brought about by artificial means, both generally
slow down the normal metabolic activity of the plant tissues and inhibit
the growth of spoilage organisms. Finally, some physiologically active
constituents of the volatile emanations from ripening fruit, notably
ethylene, can initiate premature ripening and other unwanted changes in
material exposed to the same storage atmosphere.
Precooling is the rapid cooling of a commodity after harvest,
before it is stored or moved in transit, before or after packaging.
The rapid removal of field heat is essential for preventing deteriora-
tion of the more perishable vegetables. The more quickly field heat
is removed after harvest, the longer produce can be maintained in good
marketable condition. Precooling slows natural deterioration, including
aging and ripening; slows growth of decay organisms (and thereby the
development of rot); and reduces wilting, since water losses occur much
more slowly at low temperatures than at high temperatures. After
cooling, produce should be refrigerated continuously at recommended
temperatures. Types of precooling include hydrocooling, vacuum cooling,
air cooling, and cooling with contact ice and top ice.
Hydrocooling is commonly used for vegetables such as asparagus,
celery, sweet corn, radishes, carrots, and cantaloupes. Among fruit
crops, peaches, processing cherries, and very few apples are hydrocooled;
citrus fruits are hydrocooled to a limited extent in Florida but not in
California or Texas. Hydrocooling water is recycled, and thus screens
must be used in hydrocoolers to remove trash and sediment from the water.
Hydrocoolers are an excellent source of contamination of fruit with decay
organisms. The tanks should be cleaned and the water must be changed
daily; the water must be treated with a fungicide to prevent build-up
of spores during the day. Chlorine, sodium o-phenylphenate (SOPP),
benomyl, and benlate are used in hydrocoolers to control microorganisms.
Vacuum cooling is used-for leafy vegetables, that are difficult to
cool by other methods. Field-packed products are cooled quickly and
-------
uniformly in 20 to 30 minutes. Most lettuce is now vacuum-cooled before
shipping. Some celery, cauliflower, sweet corn, carrots, and radishes
are also vacuum-cooled.
Green beans and tomatoes are often air-precooled before loading
and during transit. Grapes are precooled by air in special precooling
rooms or by forced air. They are treated with SOa prior to precooling.
Oranges are room-precooled in California. Use of contact ice and top
ice is also effective in precooling. These methods entail the use of
crushed or finely chopped ice, either placed within containers in
direct contact with produce or on top of packed containers. Contact-
and top-icing are widely used in shipping leafy vegetables, such as
spinach. Top-icing is used in shipment of root crops, such as radishes
and carrots, and some loads of celery and sweet corn. It is also used
to precool shipments of cantaloupes packed in wooden crates.
The transport of fruit and vegetables from region of production to
that of consumption can in modern circumstances involve considerable
periods of time; thus, it is highly desirable, and indeed in many cases
essential, to control the conditions during transit so as to reduce
wastage. The International Institute of Refrigeration (IIR) has made
recommendations (1963) with regard to the most suitable conditions for
the land transport of perishable foodstuffs, and their recommended
temperatures for a range of fresh fruit and vegetable products are
reproduced in Table 2.
The ranges of temperature given in Table 2 are suggested as
suitable during relatively short periods in transit (or storage) and
are not necessarily those that will give the longest possible useful
storage life for the products concerned. Further reductions in
temperature, which are limited by the need to avoid chilling injury,
will in many cases permit the maintenance of good quality during varying
periods of subsequent storage.
Optimal temperature ranges for the long-term storage of various
fruit and vegetable commodities are summarized in Table 3, which also
includes for each material an estimate of the storage life to be expected
under the specified conditions.
The humidity factor in storage also must be kept within desirable
limits. High humidities increase the danger of microbiological spoilage,
but are necessary in most cases to prevent the material from shriveling
or wilting. Most fruits keep best at a relative humidity of about
90 percent. Some leafy vegetables such as lettuce, spinach, endive,
broccoli, and celery are especially susceptible to wilting and are
better stored at even higher humidities, while certain other products,
notably onion, pumpkin, and sweet potato, maintain their quality for
longer periods when kept in a relatively dry atmosphere. Recommended
humidities for the storage of individual commodities are given in
Table 3.
-------
o
TABLE 2. RECOMMENDED TEMPERATURES FOR THE TRANSPORT AND SHORT-TERM STORAGE OF FRUIT AND
VEGETABLE PRODUCTS (International Institute of Refrigeration)
Conditions for 2-3 day transport or storage
Species
Apples
Citrus fruit
Oranges
Mandarins
Lemons and
grapefruit*
Grapes '
Lettuce
*
Melons
Onions
Potatoes
Maximum loading
temperature
OF oc
No recommendation
50
46
54-59*
46
43
'46-50*
68
—
+10
+8
+12-+15*
+8
+6
+8-+10*
+20
—
Recommended transport
or storage temperature
°F °C
37-50
36-50
36-46
46-59*
32-46
32-43
39-50*
30-68
41-68
+3-+10
+2-+10
+2-+8
+8-+15*
0-+8
0-+6
+4-+10*
-1-+20
+5-+20
Conditions for 5-6 day transport or storage
Maximum loading
temperature
°F °C
No recommendation
50
46
A
54-59
43
39
46-50*
59
—
+10
+8
+12-+15*
+6
+4
+8-+10*
+15
—
Recommended transport
or storage temperature
°F °C
37-50
39-50
36-46
A
46-59
32-43
32-39
A
39-50
30-59
41-68
+3-+16
+4-+ 10
+2-+8
A
+8-+15
0-+6
0-+4
+4-+10*
-1 to +15
+5-+20
Optimum temperatures depending on variety.
Precautions must be taken to avoid condensation on the surfaces of these products.
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TABLE 3. RECOMMENDED TEMPERATURE AND RELATIVE HUMIDITY, APPROXIMATE STORAGE LIFE, HIGHEST
FREEZING POINT, WATER CONTENT, AND SPECIFIC HEAT OF FRESH FRUITS
AND VEGETABLES IN COMMERCIAL STORAGE
Commodity
Fruits
Apples
Grapefruit California
and Arizona
Grapefruit, Florida
and Texas
Grapes, Vinifera
Grapes, American
Lemons
Limes
Oranges, California
and Arizona
Oranges, Florida and
Texas
Tangerines, Temple orang
and related citrus
fruits
Vegetables
Celery
Garlic, dry
Lettuce
Melons :
Cantaloupe (3A slip)
Cantaloupe (full slip)
Gas aba
Crenshaw
Honey Dew
Persian
Onions (dry) and onion
sets
Onions, green
Potatoes, early-crop
Potatoes, late-crop
Source: J. M. Lutz and R.
stocks. USDA Agriculture
Temperature
°F
30-40
58-60
50
31-32
48-50
00 A 0
32
;es
00 00
32
32
32
32-35
45-50
45-50
45-50
32
32
E. Hardenburg 1968
Handbook No. 66.
Relative
Humidity
Percent
90
85-90
or Qrt
90-95
85
85-90
85-90
85-90
85-90
90-95
65-70
95
85-90
85-90
85-90
DC Qfl
85-90
85-90
65-70
90-95
90
90
Approximate Length of
Storage Period
The commercial storage of fruits
Highest
Freezing Point
°F
29.3
30.0
28.1
29.7
29.4
29.1
29.7
30.6
30.1
31.1
30.5
31.7
29.9
29.9
30.1
30.1
30.3
30.5
30.6
30.4
30.9
30.9
and vegetables,
Water Content
Percent
84.1
88.8
88.8
81.6
81.9
89.3
86.0
87.2
87.2
87.3
93.7
61.3
94.8
92.0
92.0
92.7
92.7
92.6
92.7
87.5
89.4
81.2
77.8
and florist and
Specific Heat
BtuyjLh^/OE
0.87
0.91
0.91
0.91
0.86
0.91
0.89
0.90
0.90
0.90
0.95
0.69
0.96
0.94
0.94
0.94
0.94
0.94
0.94
0.90
0.91
0.85
0.82
nursery
-------
Among various supplements to refrigeration, control atmosphere (CA)
storage is the most widely used to control decay, ripening, and other
deterioration. For some fresh produce, reducing the oxygen level in
storage air and/or increasing the carbon dioxide level as a supplement
to refrigeration can provide extended storage life.
CA storages hold an important and increasing part of the apple
crop. About one-third of the stored apple is kept in CA storage. The
advantages are: (1) storage life of apples can be prolonged beyond the
normal life in regular cold storage, (2) some varieties subject to low
temperature disorders can be held for a long period at higher temperature,
(3) fruit removed from CA storage keeps longer than fruit held an equal
time in regular storage, (4) it is rodent proof, (5) relative humidity
can be maintained about 90 percent with little danger of mold growth,
(6) apples from CA storage have more of a "fresh apple" taste.
The essential features of CA storage are:
(1) Use of mechanical refrigeration to maintain temperatures of
30-32°F or 36-38°F, depending on the variety stored
(2) The storage room is specially constructed to be gas-tight
for regular CA storage or suitably tight for an externally
generated atmosphere introduced into the room
(3) In regular CA storage, oxygen is reduced and carbon dioxide
is increased by the respiring fruit. Nitrogen gas may be
introduced into the storage by portable equipment to hasten
the reduction of oxygen after the storage room is filled and
sealed
(4) In regular CA storage, excess carbon dioxide is removed by
water scrubbing, or supplemented by caustic soda when
necessary, or carbon dioxide is absorbed by dry hydrated
lime
(5) The oxygen level is usually held at about 3 percent and carbon
dioxide at about 2 to 5 percent, depending on fruit variety.
If oxygen is below 18 percent in a CA room, individuals
entering the room must wear suitable air-supplying or oxygen
masks. For loading or unloading of fruit, the atmosphere
must be flushed out to raise oxygen up to at least 18°C and
reduce carbon dioxide to a low level.
The use of modified atmospheres to supplement the benefits of
refrigeration during transit is also increasing. A variety of systems
offered by different companies provide controlled or modified atmospheres
in trucks, piggyback trailers, and railcars. They all provide an altera-
tion of the levels of oxygen, carbon dioxide, and nitrogen surrounding
the produce.
At least four systems of modifying the atmosphere in transport
vehicles are available commercially: (1) using liquid nitrogen as a
12
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refrigerant; (2) mechanical refrigeration with liquid nitrogen as a
supplement, used initially, and in transit for atmosphere modification;
(3) mechanical or ice refrigeration with dry ice (carbon dioxide) as a
supplement; (4) mechanical refrigeration with the load compartment
purged with a desired atmosphere at shipping point and then sealed
without further addition of the modified atmosphere. Low oxygen atmo-
spheres are obtained by a combustion process that burns most of the
oxygen from the air and leaves a higher concentration of nitrogen gas.
Currently, lettuce is the main vegetable shipped under a modified
atmosphere. The physiological disorder known as "russet spotting" is
reduced when lettuce is shipped in low oxygen atmospheres. However,
lettuce is damaged by accumulated carbon dioxide; therefore, hydrated
lime is placed in the cargo to absorb carbon dioxide.
Ethylene is one of the volatiles produced by most fruits and
vegetables at a certain stage of development. It is a physiologically
active compound, and when it reaches a high enough concentration, it
triggers the ripening process. Ethylene has been used to ripen honeydew
melons and tomatoes, and for degreening of citrus fruits. The control
of ethylene concentration is often necessary because of its undesirable
effects. It can induce premature ripening of fruits, defoliation of
plants, bitterness in carrots, and russet spots on lettuce.
PREPARING FRESH PRODUCE FOR MARKET
Trimming
The appearance of vegetables may be improved by removing damaged,
diseased, dead, or discolored parts. Some field trimming is desirable
for most vegetables, but sufficient wrapper leaves are left on such
crops as lettuce, cabbage, and celery for protection.
Field Packs
Berries for the fresh market, including grapes, are usually packed
into shipping containers as picked. Physical damage to these tender
fruits is reduced when they are handled only by the pickers. Similarly,
lettuce and celery are field packed and shipped to the market without
washing.
Washing
The market demands clean produce, so most fresh produce is washed
after harvest, to remove dirt, freshen the produce and reduce spray
residues. Most of the root crops, however, should not be washed until
they are marketed. Musk melons, cucumbers, and sweet potatoes are
usually cleaned by brushing or wiping dry, rather than by washing.
13
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Dumping the Field Containers
The fresh produce is transported in lug boxes or bulk bins to the
packaging line. Today, usually mechanical dumpers (hydrodumping) are
used, which transfers (dumps) the fresh produce into water.
The flume water is usually chlorinated, and depending on the type
of crop and its condition, detergent may also be used.
Fruits with encrusted dirt or insects, and fungus or spray residues
or stains require more than soaking and rinsing. In these cases, many
types of proprietary washing compounds and brush assemblies are applied,
including foaming materials, detergents, and soaps, to improve the
visual appeal of fresh produce and to reduce spore contamination on the
fruit surface.
Today, insect and other plant diseases are controlled with fewer
sprays of more effective and less stable chemicals than those used prior
to 1945, which contained arsenic and lead. Thus, chemical residues are
seldom present in hazardous amounts on any of the fruits or vegetables
at harvest time. When visible residues of insecticides, fungicides, or
calcium sprays are objectionable at harvest time, the brushing or
washing commonly used for routine cleaning generally suffices. Sodium
o-phenylphenate (SOPP) is a fungicide commonly used in the washing
process for citrus fruits. When SOPP is used for the fresh fruit market,
pH control is critical. If pH is allowed to drop, a severe burn of the
fruit can occur. For this reason, pH is usually controlled in a range
of about 11.5 to 11.8 with caustic soda. In this pH range, SOPP residues
are kept around 2-3 ppm, well within the 10 ppm tolerance level set for
fresh fruit.
The compound 2-aminobutane (butylamine) is also used sometimes in
1% aqueous solution in the flume water of citrus products. It does not
accumulate in the oil cells, and, therefore, its residue can be kept
below the 30 ppm tolerance level set for fresh citrus fruit.
Fumigation
Products
Certain production areas, states, or countries that are free from
specific crop-infesting insects or diseases require that selected
products be subjected to proven treatments for disinfestation, or be
inspected and officially certified as free from the insect or disease
in question.
The two fumigants in wide use are methyl bromide (MB) and ethylene
dibromide (EDB). (Carbon disulfide and hydrocyamic acid are no longer
in common use for this purpose.) Each must be used under carefully
controlled conditions to ensure control of insects and to avoid injury
-------
to the product being treated. EDB is recommended for citrus fruits,
stone fruits, cucumbers, green beans, and zucchini squash shipped
from Hawaii to the Mainland, whereas MB is commonly used for dis-
infestation of potatoes, sweet potatoes, and tomatoes, and under
vacuum for garlic.
Benzimidazole fungicides (principally thiabendazole and benomyl)
are the most widely used fungicides for citrus products.
Conditions 6f Use
Insect quarantine regulations can be met by fumigation with these
approved materials in a rail car, highway van, fumigation chamber, and
under tarpaulins. In each case, the facility must meet certain standards
of construction and gas tightness. Temporary sealing materials, such
as wide masking tape, are usually required at doors and vents in
transport vehicles.
Tarpaulins must be of specified materials, and the floor under the
tarps must be covered with plastic film or laminated asphalt-coated
paper to prevent gas penetration; joints between the tarpaulin and the
floor sheet must be sealed.
Fumigation chambers in buildings should have sealed sheet metal
linings and gasketed doors. False floors are desirable for good gas
distribution. A built-in blower is required to ensure circulation
during treatment.
Use levels for both MB and EDB vary from 1/2 pound to 3 pounds
per 1000 cubic feet of space, depending upon product temperature and
the specific crop being treated. Treatment at 65°F or below is not
recommended. The usual treatment time for both fumigants ranges from
2 to 4 hours.
Vapor-Heat Treatment
For certain crops that are injured by exposure to treatments that
are lethal to the insect infesting the product (citrus fruits, mangos,
papayas, pineapples, and a few vegetables'), a water vapor-heat treat-
ment may be substituted for fumigation. With this procedure, the fruits
and vegetables are exposed to saturation vapor at 110°F that is mixed
with a fine mist of water and air. Once the product reaches 110°F at
its center, it must be held there for 8-3/4 hours to ensure death of
eggs and larvae of fruit flies. Once treatment is finished, the fruits
or vegetables are cooled as rapidly as possible. The vapor-heat treat-
ment has the advantage of avoiding the use of toxic chemicals. However,
the prolonged exposure to high temperature tends to reduce the subsequent
life of the crop.
15
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Cold Treatment
A third choice for meeting plant quarantine requirements is
refrigeration of the product for a specified time. Controlled tests
have determined that certain fruit infesting insects (Mediterranean
fruit fly, Mexican fruit fly) will not survive sustained periods of low
temperature. This finding has been applied to the sterilization of
certain fruits imported to the United States from infested areas. The
plant quarantine agency of the USDA has established time and temperature
exposure requirements for the cold treatment of fresh fruit.
The following schedule is the required treatment for fruits from
areas infested with the Mediterranean fruit fly (Ceratitis capitata):
10 days at 32°F or below
11 days at 33°F or below
12 days at 34°F or below
14 days at 35°F or below
16 days at 36°F or below.
Coatings
Surface coatings, mostly waxes, are applied to certain fruits and
vegetables primarily to reduce moisture loss, and thus shriveling and
wilting. With some products, an improved glossy appearance is the main
advantage. Waxes are used for rutabagas, cucumbers, tomatoes, cantaloupes,
peppers, turnips, sweet potatoes, citrus fruits, apples, and certain
other crops.
Waxing alone does not control decay as is sometimes claimed, but
waxes containing disinfectants, such as chlorin compounds or sodium
orthophenylphenate, are effective for decay control.
Sprout inhibitors also may be incorporated into waxes. The common
components of water emulsion waxes include paraffin, carnauba,
candelilla, ouricouri, and beeswax. Rising costs of these natural waxes
has led to increasing use of synthetic resins such as high-density
polyethylene. These coatings are made from food grade components. The
use level of waxes is approximately 2-1/2 gallons of wax for 400 boxes
(about 8800 kg) of fruit.'
For orange fruits, a food dye, Citrus Red No. 2 (1-C2,5-
dimethoxyphenylazoD-2-naphthol), is applied. This dye is disolved in
an organic solvent such as ^-limoene, and the solution is emulsified in
water. Federal law limits the residues of Citrus Red No. 2 to 2 ppm.
The residues occur almost entirely on the outside of the fruit.
16
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Grading
Grading, the sorting of fruits and vegetables so that the contents
of each package will be fairly uniform, makes produce salable. Most
volume buying of fresh produce is done on the basis of grade and size.
The USDA has established uniform grades for each important produce.
Sizing of much fresh produce is based on human judgment and is a
manual operation. It may be done by sorters who select specific sizes
from a belt and place them on special conveyors to be carried to bins
for the packers. This method is commonly used for cantaloupes and large
melons.
Mechanical sizers are also available for almost all fruits and
vegetables. Practically all fresh market apples, citrus fruits, and
tomatoes that are packed in central facilities are mechanically sized.
Potatoes are usually marketed in mixed sizes with only very small and
extra large tubers eliminated. However, some fancy packs, particularly
for baking, are sized and sold by size.
Sizing by machine may entail only elimination of those units too
small or too large for market acceptability, or it may be used to
separate a number of sizes for special packs. Mechanical sizing is done
by weight, diameter, or length.
Weight sizers are commonly fabric or steel mesh belts with holes
for products of a certain size to drop through. They may have only one
size hole, as for the elimination of unsalable small sizes, or they
may consist of several sections with the smallest holes in the first
section and increasingly larger holes in succeeding sections. This
type is commonly used for sizing apples and mature green tomatoes.
Packing
A shipping container is primarily a handling unit to facilitate
moving material from one location to another. It also provides some
physical protection for the commodity, but such protection varies widely
with the type of container.
A few states have established container standards through legisla-
tion. These regulations specify what types and sizes of containers can
be used for specific fruits and vegetables. In some cases they also
require approved containers for interstate shipment of produce, thereby
prohibiting the movement of bulk produce. Other states do not have
container specifications but do require that produce be shipped in
containers recognized by the produce industry.
The sizes, shapes, construction, and materials of shipping
containers are controlled principally by the railroads. These container
IT
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tariffs are developed and enforced by the Transcontinental Freight
Bureau of the Association of American Railroads. The published tariffs
are complete with pictures, specifications, and sizes of approved
shipping containers. The tariffs specify not only what commodities
may be packed in each container, but also how the containers are to be
loaded in the rail car. Widely used shipping containers include burlap,
cotton, or plastic mesh; ventilated plastic film bags; fiberboard
cartons of full telescope (two-piece with two completely covering bottom
pieces), partial telescope (top partially covering bottom piece), or
flap-top types (one-piece); wirebound boxes of wood veneer or combi-
nations of veneer and fiberboard; sawn and nailed wooden boxes; and
molded plastic or plastic foam boxes with plastic or fiberboard lids or
with a wrap-around plastic shrink film cover.
Pads of paper-covered excelsior, corrugated paper, foam plastic,
or plastic film with entrapped air bubbles are widely used for protection
from pressure-bruising in containers for table grapes, peaches, nectar-
ines, and pears. The pads are used principally in wooden boxes, where
they provide cushioning in the bottom of the box. However, the tight
full-pack for soft fruits includes top or top and bottom pads for
protection.
Liners of waxed chipboard or smooth plastic are often used in
wooden boxes to prevent contact between the product and the sides and
ends of the back.
Paper wraps for cushioning and isolating individual fruits are now
used much less extensively for apples, peaches, nectarines, and pears
than they were before the advent of cartons as shipping containers for
these fruits. The cost of applying wraps to each individual fruit is
one factor for the decline. Until recently, the use of oiled paper
wraps or shredded oiled paper was essential for control of scald in
stored apples. Currently, a diphenylamine dip after harvest is used
effectively for scald control.
18
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SECTION 5
RESULTS AND DISCUSSION OF POLLUTION PROBLEMS IN
THE FRESH PRODUCE INDUSTRY
AIR POLLUTION
Air pollution problems arising from the handling of fresh produce
are negligible, when compared to other industries or even with some
food processing operations. Unpleasant odor associated occasionally
with the preparation of fresh produce represents the principal potential
air pollution. Generation of malodor that creates a local nuisance
occurs during the onion curing process, and more obnoxious odor is
associated with the disposal of egg-washing water. Because fresh egg
cleaning is a year-round operation, it can be objectionable to the
population surrounding the egg processing plant when the wash water
disposal is not controlled properly.
Potential air pollution problems that may arise from the preparation
of fresh produce covered in this study are as follows:
Crop Unit operation Pollution problem
Onions Field drying/curing Malodors
Grapes Preservation SOz
Lemons Ripening/storage Ethylene gas
Nuts Hulling Ethylene gas
Apples Storage COa
Eggs Washing Malodors
Fish Eviscerating Malodors
The field drying and subsequent curing of onions requires 3 to 4
weeks depending upon climatic conditions. The unpleasant odor resulting
from organic sulfide compounds creates only a local problem, and
because these operations take place in the field, residential areas are
not affected. Some artificial curing is performed under controlled
conditions at central plants instead of the field, which could create
a nuisance for the surrounding community. However, odor control in
processing plants can be achieved with the same methods as recommended
for dehydrated onion and garlic operations. Treatments of the contaminated
air with activated carbon and other possible methods used in the onion-
garlic drying industry are described in more detail in the food processing
overview section of this study.
The air pollution problem resulting from the application of SOa for
extending the shelf life of grapes is similar to that described in the
19
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food processing part of this study under sulfuring treatments of dried
fruits (J.L. Jones, et al, 1978). Emission of SOa causes unpleasant
odor, and although the compound is recognized as safe (GRA.S) for use in
foods by the FDA, it may represent a health hazard to workers who are
frequently exposed to these fumes. For this reason, the food application
of SOa is limited or banned in several countries (for example, in West
Germany and Japan) , and effective and economical but less harmful
substitutes are pursued by the industry.
Ethylene gas (CHsCHa) is applied to accelerate the ripening of
lemons and certain other fruits. The application of a very low concentra-
tion of ethylene (0.05%) is effective to induce ripening. Although the
use of ethylene requires certain precautions (it is an explosive if it
is mixed with a certain concentration of oxygen or steam) , it does not
represent any direct pollution hazard to the surrounding area.
In controlled atmosphere (CA) food storage, refrigeration is
supplemented by a modified atmosphere of reduced oxygen and increased
COa (2 to 5%) content. Such storage houses must be well sealed, and
personnel entering the storage area for repair or inspection must be
protected by air-supplying masks. However, these storage operations do
not induce any measurable air pollution to the surrounding area.
One of the most obnoxious malodors may be created by improper
disposition of egg-wash water. Wastewater generated during grading and
packing of eggs contains residues from broken eggs, and an estimated
1 percent of the eggs crack and release organic material to the wash
water. If this egg-washing water is sprayed untreated onto open fields
or if a leakage occurs from evaporator beds, a very obnoxious malodor
is generated. Therefore, before discharge, the water must be subjected
to aeration, ozonation, filtration, and clarification treatments.
Unpleasant odor from fish preparation is created by enzymatic
reaction related to the mechanisms of deterioration that are used by
bacteria. Unpleasant odors derive from the breakdown products not
absorbed by the bacteria. The effects of bacterial action may vary
considerably, depending on the species of fish, the form in which they
are landed, and the method used to protect quality. Fish such as mackerel
or herring, which are caught close inshore, are stored on the vessel in
the ungutted condition and without icing. The cleaning of such fish
onshore creates greater amounts of waste and therefore more odor problems
to the surrounding area.
Other fish taken in netting or trolling are eviscerated on the ship
and protected aboard the vessel by icing and good sanitation practices.
Consequently, they will cause insignificant odor problems, provided that
bacterial contamination ashore is carefully controlled during unloading,
sorting, and market preparation.
20
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SOLID WASTES
Solid wastes from fresh-pack fruits and vegetables originate from
washing, trimming, topping, sorting, grading, hulling, and shelling
processes. The solid wastes include leaves, stems, hulls, shells, off-
grade fruits, and other miscellaneous rejects. Major sources of solid
wastes are given in Table 4.
These wastes are organic and highly perishable in nature. However,
substantial preparation of fresh produce is completed in the field, and
therefore the organic waste is disposed of there by returning it to the
field. In central packaging operations significant waste material has
a value if it is used as a by-product (as fuel or as feed) or used in
processed food (e.g., fruit juice, apple sauce), if fresh produce
packing is combined with canning operation.
However, unused fruit and vegetable wastes in central packing
operations can cause fly and rodent problems, unpleasant odors, and
water pollution from leachate. The overall quantity of solid wastes
created by fresh fruits and vegetables is small within the waste load
created by the food processing industry. In California, solid wastes
from fresh-pack fruits and vegetables was estimated in 1967 at
409,500 tons, as shown in Table 5. This represents less than 20 percent
of the solid waste generated by the entire food industry.
WATER POLLUTION
The market demands clean produce, so most fresh produce is washed
after harvest to remove dirt, freshen the produce and reduce spray
residues. Thus, several fresh fruit and vegetable handling operations
are major water users as well as water generators. Wide ranges of
wastewater volume and organic strength are generated per ton of produce
handled. Preparation of some fruits does not include washing at all
(grapes, watermelons), other crops are washed only occasionally when
the produce is extremely dirty (cantaloupes, potatoes), while a number
of operations require the use of large amounts of water from flume-
transport within the plant, as well as for cleaning (apple, citrus).
Wastewater volume and organic strength vary among days of the
operating season. Although significant quantities of water are used
and disposed in the field for field-packed crops, there are many fruit
and vegetable packaging plants located in moderate- or small-size
communities that discharge water to municipal treatment plants.
Important unit operations that require the use of water in fresh
fruit and vegetable packing are: hydrohandling, soaking, washing,
rinsing, surface coating, and hydrocooling. Water use by the fresh
produce handling industry is summarized in Table 6.
Water used for washing, fluming, hydrocooling of fruits and
vegetables, and cleaning equipment is usually chlorinated to control
21
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TABLE 4. MAJOR SOURCES OF SOLID WASTES GENERATED IN
FRESH PRODUCE HANDLING AND THEIR UTILIZATION
Crop
Unit operation
Waste
Utilization
Apples Hydrohandling, washing
Grading/sorting
Tree nuts Hulling
Shelling
Grading/sorting
Citrus Presizing
Washing
Inspection
Celery Trimming
Washing
Lettuce Trimming
Melons Washing (occasional)
Onions Topping
Cleaning, grading
Potatoes Washing (occasional)
Sizing
Inspection
Eggs Machine loading
Candling
Packing
Fish Beheading
Cleaning
Eviscerating
Filleting
Socking (oysters, etc.)
Debris, dirt,
leaves, etc.
Undersized and
off-grade fruit
Hulls
Shells
Inedible kernels
Small fruits,
culls
Dirt leaves, etc.
Blemished fruit
Outer leaves
Soil, dirt
Soiled, diseased
leaves
Soil
Cut-off leaves
Loose scale,
leaves, etc.
Soil
Small tubers
Off-grade tubers
Broken pieces
Broken pieces
Inedible eggs
Fish
Scale
Viscera
Fish pieces
Shells
Juice, sauce
Dye, cattle feed
Fuel, charcoal,
sand-blasting
ingredient
Oil, feed
Juice
Juice
Feed
Feed
Feed or canning
Feed
Processing
Feed, oil,
bone-meal
Fish meal
Fish meal, fish
concentrates
Processing
frozen product
Fertilizer, feed
Source: SRI
22
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TABLE 5. ESTIMATED QUANTITIES OF SOLID WASTES FROM FOOD
INDUSTRY IN CALIFORNIA, 1967
Type of waste Amount (tons)
Fresh-pack fruits and vegetables 410,000
Canned, frozen, and preserved fruits
and vegetables 1,120,000
Canned fruits and vegetables 750,000
Frozen fruits and vegetables 170,000
Other preserved fruits and
vegetables 200,000
Meat processing 100,000
Dairy industry 69,000
Miscellaneous food processing 431,OOP
Total 2,130,000
Source: Cornelius, J., 1969. "Production and Disposal of Industrial
Solid Wastes in California," California Vector Views, 10, 5.
bacterial contamination and to avoid odor problems. Recommended
chlorine content in the water is between 2 and 5 ppm (as free chlorine)
at the point of application. At this level of concentration, chlorine
has no deleterious effect on the flavor, color, and nutrient content
of fresh fruits and vegetables.
On the basis of all evidence reviewed, no hazardous pollutants
(e.g., heavy metals, pesticides) occur in wastes discharged from fresh
fruit and vegetable processing facilities.
Washing of eggs requires large usage of water. A significant
portion of the water discharged by the egg producer is highly contaminated
with saline and must be treated to prevent it from coming into contact
with the underlying ground waters.
Reduction of wash water use by recycling systems cannot be initiated
by this industry because of existing FDA regulations prohibiting it.
(For more details, see discussion section 4 of Volume I of this report.)
Some experiments to recycle wash water in the citrus packing-line
were conducted by Sunkist Growers Inc., and these are discussed in
detail in Appendix G.
23
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TABLE 6. WATER USE BY THE FRESH FRUIT, VEGETABLE, EGG
AND FISH HANDLING INDUSTRIES
Crop Unit operation
Apple Hydrohandling
Soak, rinse
Grape None
Tree nuts Washing
Citrus Washing
Surface coating
Precooling
Celery Washing
Hydrocooling
Lettuce None
Melons
Watermelon None
Canteloupe Washing (occasional)
Hydrocooling
Onions None
Potatoes Water flume
Washing (occasional)
Eggs Washing
Grading
Fish Eviscerating, icing, preserving,
preparation for market,
prechilling
Oysters Retorting
Sucking
Flotation, grading
Blow washing
Drum washing
Use of water for normal equipment cleaning is not included.
Source:
PESTICIDES AND CHEMICAL PROCESSING AIDS
Fewer spray applications for insect and disease control are used
today because more effective and less stable chemicals are available
than those of arsenic and lead that were used 30 years ago. Thus,
chemical residues are seldom present in unacceptable levels in the
fruits and vegetables.
Spray deposits that cause unattractive appearances no longer present
a problem. The addition of vinegar (0.4 percent acetic acid to the wash
water) is sometimes used to reduce spray deposits on apples.
-------
Chlorine compound is often applied as a germicide in the forms of
chlorine gas, or sodium hypochloride in flume, washing, cooling, and
equipment cleaning water at levels between 2 to 5 ppm or at 10 to 20 ppm.
Sodium hypochloride is also used for the bleaching of walnut kernels.
Sodium o-phenylphenate (SOPP) is a fungicide commonly used in the
washing of citrus fruits. When this compound is applied to the washing
water, its pH must be controlled between pH 11.5 and 11.8 to avoid
damage to the fruit. This is achieved by the addition of caustic soda
(NaOH). Another fungicide, 2-amino butane, is also used in 1 percent
aqueous solution in the flume water. Benzimidazole fungicides are also
commonly used for citrus fruits.
Fumigants used for insect and disease control for citrus fruits,
stone fruits, and some vegetables are methyl bromide (MB) and ethylene
dibromide (EDB). Grapes are fumigated with sulfur dioxide gas prior
to storage and are periodically refumigated with the same compound to
control the fungus Botrytis cinerea.
Surface coatings, mostly waxes, are applied to such produce as
citrus fruits, apples, and cantaloupes. The surface coating agents are
water emulsion waxes of paraffin, carnaube, candelilla, or beeswax.
These natural products are often substituted with lower priced synthetic
resins such as high density polyethylene.
The food dye Citrus Red No. 2 (l-C2,5-dimethoxyphenylazoH-2 naphthol)
dissolved in jl-limoene solvent is applied to the surface of Florida
oranges. The residue of the dye is limited to 2 ppm maximum by federal
regulation.
Application of certain "growth regulating substances" is permitted
to control sprouting of potatoes. Maleic hydrazide CIPC (isopropyl-
N-(3-chlorophenyl carbamate) is frequently applied for this purpose.
Preparation of shell eggs requires the use of egg cleaning,
destaining, and sanitizing compounds. Compounds used in shell egg
preparation must be authorized by the USDA Meat and Poultry Inspection
Program.
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SECTION 6
APPLES
GENERAL INDUSTRY CHARACTERISTICS
The apple industry, once highly scattered geographically, is now
concentrated into specialized areas of Appalachia, the Mid-Atlantic
States, Michigan and Ohio, and the Pacific Coast or western region. Of
these, the western region is the most important producing area in the
United States.
Both total U.S. apple production and western apple production have
shifted into specialized areas. Washington, California, and Oregon are
the three most important producing states in the western region.
Concentration in these three states has been attributable in part to
the development of irrigation systems and higher yields compared to
other western states.
Washington has been the most important apple producing state in the
nation since World War I. The apple industry in this state has undergone
dramatic structural changes since World War II as a result of internally
and externally generated developments. These can be summarized as
follows:
• An approximated 80-85 percent decline in the number of
orchards and an eight- to tenfold increase in average orchard
size
• A substantial increase in average yield per bearing tree,
and development of a standard sized dwarf tree providing
efficiencies in picking
• The concentration of production in a few varieties, namely,
red, standard, Golden Delicious, and Winesap
• The decline of the terminal broker/auction function and the
dramatic growth in direct retailer buying
• The adoption of the "piggy back" method of transportation
(combination rail and truck) and mixed carloads of fruit
• The adoption of controlled atmospheric storage.
On the other hand, there are significant differences between the
Washington apple industry and that in other major producing areas.
For example:
26
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• Washington, Oregon, and California apple packers have a higher
proportion of oral or written procurement contracts than the
industry in general. Similarly, packers in this area are more
active in providing financial and management support to growers.
• Average storage time in Washington tends to be longer than
in other producing areas, and as a result, use of controlled
atmospheric storage is more prevalent than regular atmospheric
storage.
• Most of Washington's apple produce is sold outside the region
whereas most produce from other areas is sold in the same
region or nearby.
This industry is seasonal with harvesting dates commencing in late
June and ending in late November, depending on the region. Heaviest
harvesting activity normally takes place from mid-September through
early October in the major producing areas. The industry is dependent
on unskilled labor for harvesting, with local labor content averaging
44 percent in the Northwest region, 53 percent in California, 20 percent
in the Northeast, and 10 percent in the Lake States. The Northeast has
the highest content of foreign national and offshore labor (~36 percent)
followed by Appalachia (10 percent) and California (8 percent).
Per capita consumption of fresh apples has declined from 20.1 pounds
in 1960-61 to 17.0 pounds in 1976, although during the period 1967
through 1976 per capita consumption has remained relatively static,
fluctuating from a high of 18.3 pounds in 1970 to a low of 14.5 pounds
in 1973. Production during this period has increased from 3135.2 million
pounds to 3,865.1 million pounds; an average annual growth rate of
2.4 percent.
Apple varieties commonly recommended for eating fresh are Delicious,
Mclntosh, Golden Delicious, Stayman, Jonathan, and Winesap.
UNIT PROCESSING OPERATIONS
All apples that are sold in the fresh fruit market are hand-
harvested to keep them free from severe bruises, cuts, and other damage.
Harvesting aids are used, however, to improve efficiency, such as man-
positioning platforms moved by hydraulic device, combined with conveyor
equipment to carry picked fruit to pallet bins.
Lug boxes are used as field containers for apples. Fruits are
emptied from field containers into water or cleansing solutions. The
soak time in the tank, followed by a rinse with clean water as apples
are conveyed to the packing line, is usually sufficient to remove the
dust and dirt accumulated in the orchard and during transport to the
packing house. Since insect and disease control is now possible with
fewer spray applications, chemical residues are seldom present in
hazardous amounts on any of the apples at harvest time. When visible
27
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residues of insecticides, fungicides, or calcium sprays are objectionable
at harvest time, brushing and washing are used to clean fruit surfaces.
The increasing use of high sprinkler heads for irrigation in apple
orchards sometimes causes a problem in the form of mineral deposits on
apples. The deposits, from the evaporation of large amounts of water,
are unsightly and very difficult to remove by the usual cleaning
methods. The addition of 0.4 percent acetic acid to the wash water
is recommended to reduce these deposits to an acceptable level.
The use of surface coatings on apples is increasing. The coating
materials in use include petroleum and vegetable oils and waxes in
various combinations, such as carbanauba, paraffin, and liquid poly-
ethylene. The purpose of this coating is to give a bright appealing
finish to the fruit. The weight of waxed fruit, due to moisture loss,
does not differ significantly from that of untreated fruit.
After cleaning, sorting and sizing are the next operations in
packing houses. Most sorting operations begin with the removal of
fruits too small for packing and separation of trash such as leaves
and spurs.
Water has been used as handling medium for fruits for many years.
Dumping field crates of fruits into a water or a soap solution tank has
long been recognized as desirable for minimizing physical injury to the
fruit, and for removing dirt and residue. The flotation of apples
from pallet boxes submerged in water became general practice in the
early 1960s and represents a major advance in apple handling. The
success of flotation removal plus the potential advantages of presorting,
presizing and bin refilling for bulk storage led to the development of
complete hydrohandling systems.
The hydrohandling equipments vary in detail but installations for
handling apples are based on the following principles. After removal
of apples from the submerged pallet box, the fruit is moved through a
shallow water tank to a small fruit eliminator. Undersize fruit floats
through the spaces in the sizing chain and is removed by a lateral
stream and conveyor to pallet bins. The remaining fruit is floated to
a roller conveyor that removes it from the water to a sorting line.
Workers in the line remove culls and off-grade fruits to chutes or over-
head belts. The graded fruits are then returned to shallow tanks where
different diameter sizers separate the fruit into two or three sizes and
remove each size separately to accumulators. The boxes are refilled in
hydrofillers, which lower water level in the pallet boxes as the water-
borne fruit enters. Filled boxes are removed when the water level is
fully below the container. The filled box is then removed from the
hydrofiller and an empty box is put in place.
Apples to be stored in the pallet boxes are usually flooded with a
mold inhibitor solution and then drained after removal from the hydro-
filter.
28
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The present trend is to store apples in bulk, and to pack them
during the marketing period. Apples are usually not precooled for
shipment, since most of the crop is stored in. cold, and therefore cooling
is achieved in a cold storage room at only moderate cooling rates, and
the storage temperature is reached over several days.
The commercial storage of apples is usually done in atmospheres
lower than normal in oxygen (controlled atmosphere or CA storage), and
containing appreciable amounts of C02. This storage was developed
during the last 20 years and it offers important gains in extending the
market life of certain apple varieties. By elevating the storage
temperature to approximately 40°F (5°C) and altering the composition
of the atmosphere, it is now possible to eliminate chilling injury, a
common disorder of apples associated with low storage temperature. The
recommended conditions for the storage of the important cultivars of
apples grown in the United States are given in Table 7. CA storage
adds several months to the storage life of some cultivars of apples,
notably Mclntosh, and gives longer shelf-life to the fruit.
TABLE 7. CARBON DIOXIDE, OXYGEN, AND TEMPERATURE REQUIREMENTS
FOR CONTROLLED ATMOSPHERE STORAGE OF APPLES GROWN
IN THE UNITED STATES
Cultivar Carbon dioxide (%) Oxygen (%) Temperature (°F)
Cortland*
Delicious '
Golden Delicious T
Jonathan
Mclntosh
Northern Spy
Rome
Stayman
Newtown
2-5
1-2
1-2
3-5
2-5
2-3
2-3
2-3
7-8
3
2-3
2-3
3
3
3
3
3
2-3
38
30-32
30-32
32
38
32
30-32
30-32
38-40
Cortland and Mclntosh are stored in 2 percent COz the first month and
5 percent thereafter.
Delicious and Golden Delicious in Washington State are stored at 1 to
3 percent oxygen rather than at 2 to 3 percent.
Source: Ryalls, A. L., and W. T. Pentyer, 1974. Handling Transportation
and Storage of Fruits and Vegetables, Vol. 2 (AVI Publishing Co.,
Westport, Conn.)
29
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The final step in the preparation of fruit for the fresh market
is placement in the sales or shipping containers. Fiberboard containers
are largely used today as shipping containers in most apple producing
areas. Some old-fashioned wooden boxes are still used in the East.
Cartons for apples come in several sizes, but most have a capacity of
about a bushel, with net weight of fruit ranging from 36 to 44 pounds
(16.3 to 20 kg), depending on types of pack and cultivars of apples.
The cartons may be bulk-filled for marketing, but more frequently
the apples are place-packed in molded trays; individual fiberboard cells
are used as master containers for bagged or tray-packed fruits.
Unit operations in the apple industry and their contribution to
pollution are summarized in Table 8.
TABLE 8. CONTRIBUTION OF APPLE INDUSTRY UNIT OPERATIONS TO POLLUTION
Unit Operations Water Solids
Soak tank X X
Rinse X
Water Flume X
Surface coating
Sizing and grading X
Storing
Packing
Source: SRI
Utilities needed by fresh apple processors are electricity and water.
Water is used in fresh apple handling in the continuous flow-dumper,
for rinsing, and in the water flume. In the larger packing plants,
water is usually recycled and replaced only periodically. The flume
water is chlorinated and some detergent is added to remove dirt.
Surface coating compounds are applied after washing; therefore,
they do not contaminate the water.
One of the largest fresh apple packers in the State of Washington
packs 10,000 to 40,000 cartons of fruit per day and requires the following
quantities of water: 5,000 gallons (18,900 liters) in the presizing flow
dumper, 1,800 gallons (6,800 liters) per day for each of three vertical
spray-washers, 2,800 gallons (10,600 liters) in the flume, and 500 gallons
(1,890 liters) per day in the final washer. The water is recycled and
replaced every two weeks.
30
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SECTION 7
GRAPES
GENERAL INDUSTRY CHARACTERISTICS
Grapes are grown commercially in 13 of the 50 states. The industry
is separated into three general regions over the country according to
the type of grape grown: (a) regions with European-type grapes (Vitis
Vinifera), including mainly California, Arizona, and lower Texas;
(b) regions with native American-type varieties (V. labrusca, or its
hybrids with V. Vinif era) , consisting of an area east of the Rocky
Mountains and north of the Gulf States plus the Northwest and California,
which have significant commercial acreages, and (c) regions with
Muscadine grapes (V. Rotundifolia), including the South Atlantic and
Gulf States.
Grape production for the fresh market has increased slightly from
1967 to 1976 from 431,000 tons to 453,000 tons. The increase has been
about the same as population; consequently, per capita consumption has
been, on the average, about 3 pounds. These trends are not very
significant because several varieties of grapes can be used for wine,
raisins, or table use. Depending on the prices in each of the markets,
the grapes will be diverted to markets that will give the grower the
best return.
The vinifera grape, largely grown in California, constitutes about
93 percent of the grapes produced in the United States. Thompson
Seedless grapes account for more than 50 percent of the grapes supplied
for the fresh market, with Emperor, Tokay, and Ribier following in order
of importance. These grapes are produced primarily in the central valley
of California.
UNIT PROCESSING OPERATIONS
Table grapes are hand-harvested, and more than 80 percent of the
grapes are packed in the field. The trend has been toward field packing
and away from packing shed operations because of the perishability of
table grapes related to time and shipping in bulk to packing sheds.
Grape pickers bring the grapes to roadside where grader-packers fill
and close the cartons. In the case of Thompson Seedless, a crew of four
will pick and pack 200 cartons (23 pounds or 10.4 kg each) in 9 hours.
The other varieties require more time since color selection and culling
are more critical.
31
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From roadside, the cartons are shipped to a shipping station where
they are inspected, fumigated, cooled, and shipped to market. The
industry is becoming more vertically integrated with grower-packer-
shipper being one organization. The marketing function is performed
by the organization's own sales desk or by sales agents or brokers.
Cooperatives are an important element in the grape industry. Blue
Anchor, Inc., a grower cooperative, probably controls 20 to 25 percent
of the fresh grape shipments in California.
The grape harvest varies by variety and location. In California,
the harvesting of early varieties can start as early as May 20 and, with
weather permitting, the harvest can last until mid-December.
Most California table grapes are marketed 2,000 miles (1,250 km)
or more from the vineyards. Transportation is by refrigerated rail
cars or by air. Proper time of harvesting is judged by the sugar
content, using a hydrometer. It is usually necessary to go over a vine
three or more times to harvest most of the table grapes at the proper
stage.
Many varieties of the vinifera species can withstand the rigors
of handling, transport, and storage required of table grapes for wide
distribution over a long marketing period. Almost all of the table
grape is precooled and much of it stored for varying periods before
consumption.
Recommended storage temperatures are 30 to 31°F (-2 to -1°C). A
humidity of 87 to 92% is recommended. Some storage plants in California
have precooling rooms where grapes are cooled to 36° to 40°F (2-5°C)
in 20 to 24 hours before they are placed in storage. Precooling to
40-45°F (5-7°C) is advised for grapes that are to be in transit a day
or two before reaching storage. After the fruit has been precooled,
the air velocity is reduced and the grapes are fumigated with sulfur
dioxide (SOa) gas to prevent or retard decay. It has become common
practice to accumulate packed fruit in the precooler during the day
packing and to fumigate the fruit in the evening. In this way, precooling
is not delayed and fumigation can be done after most of the working crew
has left. Because grapes can be injured they should be exposed to only
the minimum quantity of SQ2. The amount of fumigant required depends on
the decay potential and condition of the fruit, the amount of fruit to
be treated, the type of containers and packaging materials, the air
velocity and uniformity of air distribution, size of the room, and
losses from leakage and sorption of walls. Under favorable conditions,
S02 concentration of 0.5 percent by volume for 20 minutes is adequate.
It is necessary to refumigate grapes at weekly intervals in storage
to prevent field infections by Botrytis cinerea from spreading to
adjacent sound fruit. For refumigation, a basic concentration of
0.1 percent for 30 minutes is adequate.
32
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Wooden lug boxes are the principal shipping containers for
European-type table grapes. Until recently, the L.A. lug, which holds
about 28 pounds (12.7 kg), was standard. Currently several sizes are
used, with net weights varying from 18 to 28 pounds (8.1 to 12.7 kg).
One of the newer lugs has beveled corners to facilitate air circulation.
Another innovation is the TKV lug, which has wooden ends and a laminated
(wood veneer-kraft paper) wrap-around piece for sides and bottom. Most
of the lugs are closed with a veneer lid, with end cleats to compensate
for some bulge when the filled containers are stacked.
The standard lug pack was satisfactory for domestic marketing, but
when subjected to long periods without SQ2 treatment, as in export
shipments, decay was often excessive. The sawdust pack in wooden
chests holding about 34 pounds (15.4 kg) of grapes and about 10 pounds
(4.5 kg) of sawdust has become the principle export container for table
grapes. If the chests are to be stored before shipment, they are packed
with a small layer of sawdust beneath the lower layer of fruit to permit
SOa fumigation during storage. Just before shipment the chest is filled
with sawdust. A small amount of sodium bisulfite is usually mixed
with the sawdust to release some SOa during transport.
Unit operations and their contribution to pollution are summarized
in Table 9.
TABLE 9. CONTRIBUTION OF GRAPE INDUSTRY UNIT
OPERATIONS TO POLLUTION
Unit operations Water Solids Air
Field packing
Precooling
Fumigation X
Storing (with periodic X
refumigation before shipping)
Source: SRI
The only utility needed by fresh grape processors is electricity.
Water is not used in fresh grape handling.
Sulfur dioxide contamination of the air surrounding the fresh grape
storage area is the only potential pollution problem in this industry.
33
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SECTION 8
TREE NUTS
Two varieties of tree nuts, almonds and walnuts, were selected for
study. While this study is oriented to fresh products, nuts are
processed to some degree prior to marketing—hulling, drying, fumigating,
bleaching, sorting, shelling, and packaging. Nevertheless, the industry
considers the nuts to be fresh nuts after these processes.
ALMONDS
General Industry Characteristics
All the commercial acreage of almonds is in California, principally
in the central valley, in a belt about 700 miles (438 km) long. Between
1957 and 1976, production increased from 76,600 tons (in-shell basis)
to 233,000 tons. In 1976, there were 256,700 bearing acres and 79,300
acres of nonbearing trees. Trees begin bearing after 3 years; however,
a tree is considered of commercial bearing age only after it reaches
6 or 7 years.
The harvest season runs from about August 5 to November 15 and the
crop year begins July 1 and ends June 30 the following year.
About 65 percent of the crop is processed and marketed by the
California Almond Growers Exchange, a cooperative. About 27 percent
is processed and marketed by four major companies, one a cooperative,
and the remainder of the crop is handled by six very small operations.
Per capita consumption has increased from 0.31 pounds (0.14 kg)
in 1967 to a record high of 0.43 pounds (0.20 kg) in 1976 (shelled
basis); however, shipment for domestic use accounts for only 38 percent
of the industry's shipments. The remainder is exported. The large
increase in U.S. production has been made possible by the industry's
successful marketing efforts in foreign countries. Figure 1 shows the
flow of processed almonds to various market outlets in 1973-74.
Unit Processing Operations
Harvesting starts when almonds in the shady portions of the tree
show shriveling and cracking of the hulls. When they are ripe, tree
nuts fall to the ground. However, when they drop unassisted, the harvest
covers such a prolonged period that the nuts are commercially unsatis-
factory. The usual harvesting procedure is to knock the almond to the-
ground, usually with mechanical shakers or knockers.
-------
DISTRIBUTION
OF ALMONDS
1973-74
DOMESTIC
PRODUCTION
* INCLUDES GlfT PACKERS. EXPORTS AND OTHER FOOD MANUFACTURERS
**INCLUDES MAIL ORDER AND UNALLOCATED,
O 1.5 WHOLESALERS
O 1-5 RETAILERS
O 0.7 MIXERS
O 0.8 OTHER*
51-6 EXPORTS
H-* CONFECTIONERS
O 7.6 MIXERS S SALTERS
6.5 CEREAL MANUFACTURERS
O 4.5 BAKERS
3.8 OTHER FOOD MANUFACTURERS
3.7 ICE CREAM MANUFACTURERS
2.5 RETAILERS
O 2.1 WHOLESALERS
2.0 OTHER**
NEC. 933 EBS-75 ID
SOURCE: USDA, Fruit Situation, ERS, March 1975, P 53.
SA-5619-60
Figure 1. Distribution of almonds 1973-7^
35
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After several days of drying on the ground the almonds are picked
up with the hulls still attached to the shell. Most of the commercial
almond orchards now use inertia limb shakers for nut removal, windrowers
for concentrating, and pick-up machines for gathering the nuts. They
are then run through the huller to remove the hulls; however, practically
all of the shells remain intact. After hulling, the nuts are sacked or
loaded into bulk bins and taken to the receiving station.
Growers usually deliver their crops to the cooperative in the
unshelled form through local receiving stations. The cooperative supplies
its members with burlap bags that have been vacuum-cleaned, repaired, and
fumigated. Where feasible, bulk handling of growers' deliveries is
accomplished in pallet boxes of approximately one-ton capacity. These
are designed for completely mechanized handling.
The nuts are then dried in almond driers or dehydrators to the
point where they can be broken without bending the kernel and then are
delivered to the processing plants. At that point the almonds are
either shelled if they are to be sold as kernels or bleached if they
are to remaind intact and sold as shell almonds. However, except for a
relatively small quantity sold in mixed nuts during the holiday season,
practically all are now marketed as shelled nuts.
Almonds are assembled for shelling in huge storage bins; from these
they pass to a battery of cracking machines with a capacity of 175 in-
shell tons per day. The kernels are mechanically separated from the
shells and represent more than half the almonds by weight. The cracking
percentage varies with different varieties. By passing through an
electric eye device, kernels that are broken, chipped or discolored,
along with foreign material, are separated and diverted to special uses.
In-shell almonds will retain good condition and flavor for 7 to
8 months at room temperature if they are reasonably dry when stored and
the room humidity is below 70 percent. If prolonged storage is required
for in-shell almonds, they should be held at 50°F (10°C) or below, and
will usually remain in excellent condition for as long as 2 years at
32°F (0°C) with about 75 percent humidity.
The perishability of almonds is increasing by shelling. Air
storage at 32°F (0°C) with 60 to 75 percent relative humidity is usually
satisfactory for 15 to 16 months.
Shelled almonds stored under vacuum maintain good flavor and color
for 20 to 24 months at 50°F (10°C). The vacuum process is now widely
used for the preservation of roasted and variously flavored almonds,
which are marketed in consumer-size metal and glass containers. Some
packaging materials such as pliofilm and polyethylene should be avoided
because they import an undesirable odor to the nuts.
36
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WALNUTS
General Industry Characteristics
More than 99 percent of U.S. commercial walnut production is in
California and is centered in the San Joaquin and Sacramento Valleys.
A small acreage of walnuts is found in the Willamette Valley of Oregon.
Production has increased from 98,000 tons (in-shell basis) in 1967 to
183,700 tons in 1976. In 1976 there were about 169,700 acres
(68,678 hectares) of commercial bearing acres in California and
35,900 acres (14,529 hectares) of nonbearing trees. Trees begin bearing
at 4 years and reach commercial bearing age at 8 or 9 years.
The harvest season runs from September 15 to December 30 while the
crop year begins July 1 and ends June 30 the following year.
In 1976, about 70 percent of the walnuts were sold shelled compared
to 42 percent in 1973-74. The distribution of walnuts during the
1973-74 season is shown in Figure 2. Walnuts are used primarily as a
food ingredient by households as well as industrial users.
About 53 percent of California walnuts are handled by the Diamond
Walnut Growers, Inc., a cooperative. Other major companies are Maifair
Packing, Continental Nut, Guerra, and several smaller operations.
Per capita consumption has increased from 0.35 pounds (0.16 kg)
(shelled basis) in 1967 to 0.53 pound (0.24 kg) in 1975. Exports
accounted for about 25 percent of the industry's shipments in 1975 and
is the fastest growing outlet for the industry.
The only commercially important walnut is the English or Persian,
Juglans regia, which is grown for the most part in California and Eastern
Oregon. More than 80 percent of the walnut crop is handled by Diamond
Walnut Growers Inc. Facilities of this association are located in
Stockton, California.
Unit Processing Operations
Walnuts drop naturally over about a 2-month period. Trees are
shaken by mechanical shakers, before the nuts drop naturally, in order
to-obtain the highest quality. The currently used method of harvest
involves mechanical trunk or limb shakers, windrow machines to con-
centrate the nuts between rows, and pick-up machines to gather the
windrowed crop. The nuts are hulled and dried immediately after shaking
to avoid damage from rain or fog, which can increase the percentage of
culls. Hulling is done by hand or by machine.
Once the kernel is mature, the biggest obstacle to harvesting is
the large amount of green "sticktights" that fall during the first
Walnut with hull sticking to the shell.
37
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DISTRIBUTION
OF WALNUTS
1973-74
>-^ IN-SHELL
100%^* MARKET
£ 1UU1
2fe»^
DOMESTIC— v
PRODUCTION \
SHELLED
MARKET
(156,060,000 IBS.) 41.6%
CROCERV RETAILERS2.S
OTHER RETAILERS 2.0
29.9 GROCERY WHOLESALERS
20.0 EXPORTS
2.4 OTHER NUT HANDLERS
2.8 RETAILERS
1.5 MIXERS & SALTERS
1.8 OTHER*
23.1 GROCERY WHOLESALERS
4.1 OTHER FOOD MANUFACTURERS
3.1 BAKERS
' 4.5 RETAILERS
} 2.1 EXPORTS
1 1.7 ICE CREAM MANUFACTURERS
) 1.0 CONFECTIONERS
) 2.0 OTHER**
* INCLUDES ICC CREAM MANUFACTURERS. CONFECTIONERS AND GlfT PACKERS.
**INCLUDESOTHER HUT HANDLERS UIXE RS & SAL TCflSAHO CEREAL MAHUFACTURCRS
USOA
NEC. 934 ERS-75 111
SOURCE: USDA, Fruit Situation, ERS, March 1975, P.52.
SA-5619-61
Figure 2. Distribution of walnuts 1973-7**
38
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shaking. While water-sweating can be used to assist in removing the
hull, it is not always satisfactory. Use of ethylene gas is more rapid
and effective, and has been used successfully in the warm interior
districts of Southern California. The green nuts are separated out and
placed in an airtight bin equipped with forced draft ventilation. The
gas is injected at the rate of one cubic foot of ethylene to 1,000 cubic
feet of air with temperatures ranging between 70° and 80°F (21 and 27°C).
The bin is ventilated with fresh air every 12 hours for 20 minutes to
1% hours; regassing is done after each ventilation. Treatment is
continued until 96 to 98 percent of the hulls are removed, which requires
24 to 72 hours.
Spray applications of 500 to 1,000 ppm ethephon (2-chloroethyl-
phosphoric acid) 2 to 4 weeks before harvest have also been used to aid
mechanical harvest. As a result of such spray applications, hulls
dehusc readily, and complete nut removal with single mechanical shaking
occurs as much as 3 weeks earlier than normal harvest.
The nuts are washed after the hulling to remove the juice of the
crushed hulls, which otherwise will stain the shell and make bleaching
difficult or impossible. Large, cylindrical drums are used with coarse
wire netting to wash the nuts. The nuts are revolved in this cylinder
under a stream of water for 2 to 3 minutes.
After hulling and washing, the nuts must be dried immediately to
remove excess moisture from the kernels and shells. Nuts adequately
dried should average about 6 percent moisture. Use of dehydrators has
replaced sun drying. Forced, heated air is sometimes used, but pro-
longed drying must be done at relatively low temperatures (under 110°F
or 43°C). However, final drying before cracking can be accomplished
quickly by the use of much higher temperature air on a belt trough
dryer, at 200°F (93°C). At this temperature, moisture can be reduced
to 4.2 percent in 17 minutes.
After curing, the nuts are delivered to a local packing house. On
reaching the packing house, the nuts are passed under a vacuum hood
that removes the "blanks" or improperly filled nuts. Nuts with full
kernels pass on to a belt where they are hand-hulled, and the obviously
imperfect nuts are removed. The nuts then pass through a revolving
drum containing a bleach solution of sodium hypochloride for 2 to
3 minutes. The bleach is harmless to humans and the kernels; it removes
dirt and stains, leaving the nuts uniformly bright and clean. The nuts
then pass to a belt where those nuts with imperfections revealed by the
bleaching are picked out (e.g., wormy, moldy). The nuts are then sized
mechanically into three standard grades (large, medium, baby). Each
size grade of nut is run through a large thoroughly ventilated bin
where the moisture that was absorbed in the bleaching process is
removed. From the drying bins, the nuts pass on to another culling
belt; then they are individually brand-labelled and packed mechanically
into 1- to 2-pound cellophane bags or larger cartons. Over 80 percent
of the in-shell walnuts are marketed in cellophane bags; the rest are
packed in bulk cartons.
39
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Many of the walnuts picked out as culls have good kernels and are
cracked along with others by machine. The kernels are separated
electronically from the cracked nuts on a color basis, and are sold
as shelled walnuts, which constitute about 40 percent of the crop.
Kernels are sold in 4- and 8-ounce (113 and 226 grams) vacuum cans.
In vacuum canning, machines do the filling, weighing, pulling of vacuum,
and sealing. Kernels not used in consumer packages are packed in
cartons for commercial use in ice cream, cookies, cakes, and other
prepared foods.
Inedible kernels and shells are processed into various by-products
(after a wet separation technique removes the nutmeat residues) such as
oil for paints and walnut meal for poultry and cattle. A high per-
centage of shells are burned in the plant's furnaces for fuel. Part of
the shells are sold for sand blasting uses. Walnut hulls are used in
dye fabric for rugs and Japanese style dresses.
Properly dried in-shell walnuts will remain in good condition for
a year or more at 32°F (0°C) with 60 to 75 percent humidity. There are
no critical temperatures for storing nuts. Other conditions being
equal, the lower the temperature, the longer the shelf life. Life may
be extended from two to three times with each 20 degree (11°C) drop in
temperature. The freezing point is 14°F (-10°C) for walnuts. In-shell
walnuts can be kept at temperatures of 50°F (10°C) or above for only
6 months or less. Shelled nuts to be held from one harvest season to
the next, without appreciable loss in quality, must be held at 36°F
(2°C) or lower; those to be held for 6 to 9 months must be kept at
48°F (9°C) or lower, and all nuts stored for 4 to 6 months should be
held below 68°F (20°C). The period of storage, at a given temperature,
is doubled if the nuts are unshelled.
Much research has been done with various antioxidants in attempts
to control rancidity in shelled walnuts during storage and marketing.
The chemical antioxidants BHA and BHT, when used in vegetable oil and
applied to shelled nuts, reduce the oxygen absorption by approximately
two-thirds. A BHA+PG formulation is even more effective in reducing
oxygen absorption.
All nuts readily absorb odors and flavors from the atmosphere and
surrounding products. Certain gases such as ammonia react with the
tannin in the seed coats of nuts during curing, and turn the nuts black.
For these reasons, the atmosphere in the nut storage room must be free
of all odors.
Cellophane is the preferred packing material for consumer size
packages because both Mylar and Saran films contain a static charge
that causes the chaft from walnut meats to cling to the surface of the
package. Laminated aluminum foil pouches, sealed gastight, are also
used for packing walnut meats.
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Tree-nut industry unit operations and their contribution to
pollution are summarized in Table 10.
TABLE 10. CONTRIBUTION OF TREE NUT INDUSTRY UNIT
OPERATIONS TO POLLUTION
Unit operations Water Solids
Almonds
Drying on ground
Huller X
Drying
In-shell
Storage
Shipping
Shelled
Cracking X
Sorting X
(Bleaching, roasting, flavoring) X X
Packing
Storing
Shipping
Walnuts
Hulling (hand or ethylene treatment) X
Washing X X
Drying
In-shell
Grading, sorting x
Bleaching X X
Fumigation
Packaging
Storage
Shelled
Fumigation
Size grading
Shelling
Sorting x
Inspection
Dried X
Antioxidant treatment
Fumigation
Packaging
Storing
Shipping ^
Source: SRI
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Utilities needed by nut processors are gas, electricity, and water
and refrigeration. Only insignificant amounts of water are used in the
fresh nut processing operations when in-shell walnuts or shelled
almonds are bleached. The hulls or almonds are used as cattle feed,
and the shell material is used either for charcoal manufacture, or
burned as a fuel in the roasting operation. Ethylene gas for dehulling
walnuts and fumigation of the nuts present potential air pollution
problems.
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SECTION 9
CITRUS FRUITS
GENERAL INDUSTRY CHARACTERISTICS
Oranges, lemons, and grapefruit were the citrus fruits selected
for study. All the commercial crop for the fresh market is produced in
California, Arizona, Texas, and Florida. The relative importance of
these growing areas in supplying the fresh market varies by type of
fruit; consequently, each type will be considered separately.
Oranges
Oranges produced in Florida are primarily used for processing
rather than as fresh produce. Approximately 93 percent of the oranges
are processed into orange juice. In California and Arizona the reverse
is true, with 64 percent of the crop going to the fresh market, whereas
in Texas the crop is divided about equally between processing and the
fresh market. In total, California-Arizona shipments account for about
67 percent of total fresh orange shipments, Florida accounts for
27 percent, and Texas accounts for 6 percent.
California-Arizona production for the fresh market is dominated
by the navel variety of oranges, which is the preferred orange for
eating and accounts for about 38 percent of the oranges shipped to the
fresh market. Valencia oranges from California-Arizona is the other
major variety and account for about 29 percent of the shipments.
In Florida, about 55 percent of the oranges are of the early and
midseason variety and the remainder are Valencias.
Production of oranges for the fresh market has shown no significant
trend from 1967 to 1976 and has averaged about 3,900 million pounds
(1,770 million kg) during the past 3 years. Per capita consumption
has declined from 18 pounds (8.2 kg) in 1967 to about 15 pounds (6.8 kg)
in 1976. California-Arizona and Texas production for the fresh market
has been increasing, but this increase has been offset by a decline in
Florida production.
The movement of oranges from harvest to packer to wholesaler and
retailer is different in Florida than in California-Arizona. The
Florida orange industry is such that many of the major marketing and
other related policy decisions are generated and implemented at the
processor level. Hence, the share of the crop channelled through fresh
outlets, and the resulting fresh fruit prices, are dependent upon
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processing activities. Returns to growers in effect are determined by
returns to processors.
Figure 3 is a flow diagram of the marketing channels for Florida
fresh oranges.
•Grower-
,Bird-Dog,
-Packer—
-Processor
Wholesaler
-Retailer
Consumer-
Figure 3. Marketing channels of Florida oranges.
Growers and fresh fruit packers have integrated by forming
cooperatives. There are four types of cooperatives in the Florida
citrus industry. These are:
(1) Cooperatives where fresh fruit packinghouse eliminations and
some direct grower shipments are processed.
(2) The cooperative processor, where packinghouse eliminations
and some direct grower shipments are processed.
(3) Centralized cooperatives that receive both fresh and processed
fruit.
(4) Federated cooperatives, which are essentially centralized
selling cooperatives that only market the production (fresh
or processed) of the individual member packer or processor.
-------
Cooperatives have also been formed that are affiliated with
particular corporations. They are classified as cooperative fruit
associations. The cooperative carries out the procurement function
and the corporation performs the processing marketing function.
Fruit is received at the packing/processing plant on a priced or
nonpriced (deferred price) basis. Priced fruit may come from individual
growers but it comes typically from the intermediate handler or
"bird-dog." Purchase of the fruit may be made on a bulk basis or on
a price-per-box basis. Fruit that is priced by a deferred pricing
arrangement goes through corporate participation plants or cooperatives.
The price realized for this product depends on the profits of the packer/
processor and the method of price determination.
Florida citrus producers and shippers operate under a federal
marketing agreement that establishes standard grades for fresh fruit
entering interstate commerce. The state Citrus Code establishes minimum
maturity standards for fresh fruit. All firms who take title to fruit
for resale as specified by the Florida citrus code must be licensed and
bonded.
The California-Arizona orange industry is dominated by Sunkist
Growers, Inc., a grower cooperative. About 80 percent of California-
Arizona orange production is handled by this organization. The
organization of Sunkist Growers, Inc., includes its member growers,
local associations, district exchanges, and the affiliated Fruit
Growers Supply Company. About 8,000 citrus growers in California and
Arizona are members of the Sunkist Growers, Inc., and its affiliated
organizations. These growers are responsible for performing all
cultural practices in the production of citrus. All property rights or
interests in Sunkist Growers, Inc., are held by member-growers.
A local association is a nonprofit cooperative association of
growers. It represents its members in the district exchange and in
Sunkist Growers, Inc., and usually provides packing services. Fifty
local associations have a combined membership of about 4,000 growers.
Local associations provide facilities for assembling, washing, grading,
and preparing growers' fruit for market. The fruit is physically pooled
and final pooling and distribution of proceeds is made to growers.
The 4,000 growers, who use about 50 licensed packers, must be
direct members of a cooperative district exchange. The licensed packers
are restricted to picking, packing, and shipping fruit as authorized by
Sunkist Growers, Inc. All marketing functions for these growers are
conferred on the district exchange and Sunkist Growers, Inc. There are
20 district exchanges in the Sunkist organization, and these are
composed of growers who have their fruit packed by licensed packers,
or of associations of growers operating as local associations, or both.
Grower-members participate directly in representing and voting, in
handling and distributing sales proceeds, and in allocating property
rights. They reserve the right of final decision on price, destination,
and transportation until after the sale has been made by Sunkist.
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The California-Arizona orange industry operates under Federal
Order (P.O.) 907 for navel oranges and F.O. 908 for Valencia oranges.
These orders regulate permissible size and weekly volume. All shipments
to markets in the United States and Canada are covered by these orders.
Marketing orders for each variety are supervised by industrywide admin-
istrative committees that recommend weekly volumes of shipments and
compute a prorate base and allotment for each shipper. The committees
consist of six growers, four handlers, and one member not directly
connected with the citrus industry.
Grapefruit
Historically, Florida has been the dominant grapefruit producing
area in the United States, with approximately 75 to 80 percent of the
crop. Structural changes affecting the industry in Florida can be
summarized in terms of:
• An increase in yield per acre that is greater than.the other
major producing areas. Florida grapefruit yields reached a
high of 21.3 tons (19,340 kg) per acre in 1966-67, up from
13.3 tons (12,076 kg) per acre in 1954-55. Recently yields
have remained relatively stable at 17 tons (15,436 kg) per
acre.
• The continuing interdependence of fresh grapefruit production
with that of processed grapefruit. Florida accounts for
approximately 80 percent of processed grapefruit, and grape-
fruit for processing now represents approximately 60 percent
of total production versus less than 50 percent in the late
1950s.
• A relative scarcity of land as urban sprawl consumes agricultural
land previously used for producing grapefruit.
• The existence of two separate and distinct production areas—the
Indian River district and Interior Florida. Between these two
areas, there are product differentiations, differences in
distribution channels, and separate federal marketing orders.
• The growth of direct retailer buying changing the structure of
grapefruit packing, communication facilities, and types of
selling efforts. Direct retail buying now accounts for
approximately 80 percent of the crop.
• The effects of freezes in 1957-58, 1962, and 1976, which have
necessitated new plantings and some disruption to production.
Per capita consumption of fresh grapefruit has declined marginally
from 10.1 pounds (4.6 kg) in 1956-58 to 8.9 pounds (4.0 kg) in 1974-76.
However, consumption per capita during the period 1966-67 through
1975-76 has increased marginally due to renewed consumer interest in
nutrition and diet. Production during this period has increased from
2,055.8 million pounds (933 million kg) to 2,623.5 million pounds
(1,191 million kg), an average annual growth rate of 2.7 percent.
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In California-Arizona, a Federal Order covers grapefruit grown in
Arizona and the desert areas of southeastern California only. The P.O.
regulates grades and sizes, but has no volume stipulation. The
administration of the order is the same as that for oranges in California-
Arizona.
Lemons
California-Arizona account for more than 90 percent of the lemon
shipments to the fresh market. Production has increased from about
707 million pounds (320 million kg) in 1967 to 839 million pounds
(318 million kg) in 1976. Per capita consumption, however, has declined
from 2.3 pounds (1.04 kg) to 1.8 pounds (0.82 kg).
In California-Arizona, lemons are harvested, processed, and marketed
the same way as oranges and grapefruit. Sunkist Growers provides the
same services and organizational structure for all three citrus fruits.
There is a F.O. for lemons, P.O. 910, that is administered by a
committee consisting of 13 members—8 growers, 4 handlers, and 1 non-
industry representative selected by grower and handler members. The
committee recommends weekly volumes of shipments and computes a
prorate base and allotment for each shipper.
UNIT PROCESSING OPERATIONS
Proper handling of citrus fruits from the tree to the consumer
involves many operations that are continually changing. Manual handling
is gradually being replaced by various kinds of mechanization and bulk
handling of the crop.
Picking
Citrus fruits are harvested in the United States throughout the
year, depending on the growing area, the kind of fruit, and their
respective varieties. The approximate commercial shipping seasons for
Florida, California-Arizona, and Texas citrus fruits are illustrated
in Figures 4, 5, and 6, respectively (Ashrae, 1971). The picking
operations are conducted by trained crews from independent packing-houses
or large associations. These organizations are more cognizant of market
conditions than the individual growers and can schedule picking to meet
market demands. The fruit not handled through cooperatives is normally
sold on the tree to the shippers or processors and is picked at the
latter's discretion.
The fruit is .carefully removed from the trees by special clippers
or by pulling and it is placed in picking bags that are emptied into
field boxes. An increasing amount of fruit is handled in bulk, and the
pickers put the fruit into pallet boxes or wheeled carts. In some cases,
especially for processing, the fruit is loaded loose into open truck
trailers. More than half of the entire Florida crop is processed.
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Citrus fruits
Oranges
Hamlin
Parson Brown
Pineapple
Valencia
Temple Orange
Murcott Honey Orange
Dancy Tangerine
Tangelos
Orlando
Thornton
Minneola
Seminole
Grapefruit
Marsh
Duncan
Ruby Red
Thompson Pink
Tahiti or Persian Lime
SOURCE: ASHRAE Guide and Data Book Applications
(Am.Soc. Heating, Refrigerating, and Air
Conditioning Engineers, New York, N.Y. 1971
Figure k. Approximate commercial shipping
seasons for Florida citrus fruits-
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Citrus fruit
and location
Oranges
Washington Navel
North California
Central California
South California
Valencia
Central California
South California
Desert
Lemon
Central California
South California
Desert
Grapefruit
Central California
South California
Desert
Dancy Tangerine
SOURCE: ASHRAE Guide and Data Book Applications
(Am.Soc. Heating, Refrigerating, and Air
Conditioning Engineers, New York, N.Y. 1971.)
Figure 5- Approximate commercial shipping
seasons for California and Arizona
citrus fruits.
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Citrus fruits
Oranges
Hamlin
Marrs Early
Washington Navel
Pineapple
Valencia
Grapefruit
Marsh
Ruby Red
Thompson
SOURCE: ASHRAE Guide and Data Book Applications
(Am.Soc. Heating, Refrigerating, and Air
Conditioning Engineers, New York, N,Y, 1971)
Figure 6. Approximate commercial shipping
seasons for Texas citrus fruit.
50
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At the beginning of the season, the fruit is often spot-picked in
order that only the riper, outside, or larger fruit is harvested. Later
on, the trees are picked clean. In California, lemons are usually picked
for size with the aid of sizing rings.
Picking is expensive, time-consuming, and laborious, and considerable
research is being conducted to reduce the labor in harvesting. Various
devices being tested include mechanical platforms and positioners, tree
shakers with catch frames, and air blasts for removal of fruit.
Mechanical harvesting, however, is still far from a commercial reality,
and very little mechanically harvested fruit is expected to be used for
fresh market because of surface blemishes that occur during the operation.
Handling
In the packing-house, citrus fruits are prepared for shipment by a
number of carefully directed operations that are varied to suit the
variety or quality of the fruit and the market requirements. The general
aim is to keep physiological breakdown and decay to the minimum and to
prepare the fruit in an attractive manner.
After the fruit is received at the packing-house, it is removed
from the boxes or bulk containers by careful dumping to prevent damages
to the fruit. It is then presized to remove the fruit that is too large
or too small. Washing may be preceded by floating the fruit through a
soak tank, which usually contains a detergent for cleaning and sometimes
an antiseptic for decay control. The washer is generally equipped with
transverse brushes that revolve up to 200 rpm. If not applied at the
soak tank, soap or antiseptic may be dribbled or foamed on the first
series of brushes. The fruit is then rinsed by a fresh water spray.
The fruit is dried mechanically by passing under fans that circulate
warm air through the moving fruit. When dried, the fruit is polished
and waxed, and then passed over roller conveyor grading tables. After
grading, it is conveyed to sizing equipment that separates the fruit
into the standard sizes being packed and drops them at stations for hand
packing, or conveys them to automatic or semiautomatic box-filling or
bagging machines.
The packing-house handling of California lemons for fresh market is
interrupted by an extended storage period. After washing, the fruit is
conveyed to a sorting table for color separation by electronic means or
by human eye. Usually four colors are recognized; these are designated
as dark green, light green, silver, and yellow. The dark green is a
full green; the light green, a partially colored green (a green with
color well broken); the silver, fully colored with a green tip (sylar
end); the yellow, fully colored and mature with no green showing. Dark
green fruit has a normal storage life of from 4 to 6 months; and yellow,
3 to 4 weeks. These periods are approximate, as the keeping quality of
fruit varies considerably with season and grove. A light concentration
of water wax emulsion is usually applied to lemons before they are put
into storage.
51
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After storage, lemons are waxed, and then sized and packed. Post-
storage washing to remove mold soilage is desirable but is not
recommended unless a washer incorporating very soft roller brushes is
used.
Shipping and storage containers vary considerably for the various
types of citrus. Fiberboard cartons have become the standard for use
in California. A substantial part of California and Arizona oranges
and grapefruits that arrive at eastern market in bulk cartons go to
repackers for distribution in 5- or 8-pound (2.25 or 3.6 kg) poly-
ethylene bags. In Florida, the 4/5-bushel fiberboard carton and
4/5-bushel wirebound crate have replaced the larger containers previously
used. In addition, more than 15 percent of the Florida fresh fruit is
consumer-packed in mesh and polyethylene bags that are shipped loose or
in 40-pound master cartons. After the packages are filled and closed,
they are conveyed to precooling rooms to await shipment, or directly to
standard refrigerator cars or trucks. The containers are stacked so
that air distribution is uniform throughout the load.
Accelerated Coloring or Sweating
All varieties of citrus fruit must be mature before they are picked.
Color is not always a criterion of maturity. The natural change of
color in oranges from dark green to deep orange is a gradual process
while the fruit remains on the tree, the fruit remaining dark green from
its formation to the time it is nearly full size and approaching
maturity, when a stage is reached where the color changes may become
very rapid. The color change is influenced greatly by temperature
variations. A few cold nights followed by warm days may be sufficient
to completely color oranges that were previously very green. The color
changes in lemons and grapefruit are similar, except that the final color
is yellow. Unfavorable weather conditions may delay coloring even after
maturity.
Up to a certain point, the natural color changes in Valencia
oranges follow the trend described, but complete or nearly complete
orange color generally develops some time before the fruit is mature.
Some regreening of Valencias may occur after the fruit has reached its
prime. Navel oranges in California, as well as the Florida varieties of
Hamlinj Parson Brown, and Pineapple harvested in late fall and early
winter, may be mature and of good eating quality although the rind is
green in color. Grapefruit, lemons, tangerines, tangelos, and other
specialty fruits also may be sufficiently mature for eating before they
are fully colored. Since the consumer is accustomed to fruit of char-
acteristic color, poorly colored fruit is put through a coloring or
degreening process in special rooms, bulk bins, or trailer degreening
equipment. These units are equipped for maintaining temperatures and
humidities at desired levels. Approximately 10 ppm ethylene in the air
is maintained. The concentration of ethylene and the duration of the
degreening periods depend on the variety of fruit and the amount of
chlorophyll to be removed. During the operation, fresh air is intro-
duced into the room, and a relative humidity of 88 to 92 percent is
52
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maintained. In Florida, temperatures of from 82 to 85°F (26 to 29°C)
usually are used, while in California temperatures of 65 to 70°F (17
to 22°C) are used. In California, the process is called sweating
instead of coloring or degreening.
Oranges, grapefruit, and specialty citrus fruits that require
ethylene treatment are frequently degreened as soon as they are delivered
to the packing-house. Lemons in California and all citrus fruits in some
packing-houses in Florida are washed and graded or color separated before
being degreened.
A high percentage of Florida's early and midseason varieties of
oranges receive color-added treatment. The treatment, which is done
with a certified food dye, causes the rind of pale fruit to take on a
brighter and more uniform orange color and is usually performed in
addition to that of degreening with ethylene gas. In this process the
fruit is subjected for 2 or 3 minutes to the dye solution, which is
maintained at about 120°F. The color-added treatment can be given in
an immersion tank filled with vegetable dye solution, or the dye can
be flooded on the fruit as it passes on a roller conveyor. The color-
added tank is located after the washer and before the wax applicator.
Oranges with desired color at harvest time, as well as tangerines and
grapefruit, are bypassed around the dye tank, or the flow of dye may
be cut off as the fruit passes over the equipment. Standards for
maturity are slightly higher in Florida for oranges given the color-
added treatment. California oranges are not artificially colored.
Precpoling
Precooling is usually accomplished by use of refrigerated air in
specially designed precooling rooms after the fruit is packed. It may
also be accomplished in the refrigerator car after it has been loaded.
Hydrocooling is used in a number of Florida packing-houses. The
fruit is cooled by passage through a flood-type hydrocooler on a
screen conveyor or in pallet boxes. Oranges are usually cooled for
20 minutes with 32°F water. The pulp temperatures are reduced 20 to
25 degrees during the process. After cooling, the fruit is packed in
perforated polyethene bags or fiberboard cartons and loaded directly
into precooled rail cars or trailers. Refrigerated storage rooms are
provided for temporary holding of surplus fruit.
Because the fruit is moist after packing, an antiseptic, usually
0.1 percent sodium-o-phenylphenate (SOPP), is maintained in the hydro-
cooling water to prevent mold. Decay control is obtained sometimes by
treating fruit, before packing, with a dip of 2 percent SOPP plus
1 percent hexamine. Hydrocooled citrus should be refrigerated until
consumed.
In California, air precooling is used for oranges but not for
lemons or grapefruit, while in Florida precooling is common practice
53
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for most citrus fruits, particularly such specialty fruits as Temple
oranges, tangerines, and tangelos.
Storage
Citrus fruits often carry incipient fungus infections when harvested.
Three chemicals are approved by the Food and Drug Administration for
postharvest use on citrus. Thiabendazole (TBZ) is the most effective
and can be applied as a flood or spray after washing and before drying
and waxing, or may be incorporated in a water wash. For protection
during degreening, the fruit may be drenched with TBZ prior to its
entering the coloring room. Orthophenylphenol (or its sodium salt,
SOPP) is used alone or in combination with hexamine in the soak tank,
in the hydrocool water, or is applied on the brushes before rinsing.
It may also be incorporated in the wax coating. Biphenyl, a volatile
fungistat, is impregnated in paper wrappers, box liners, and cartons.
It evaporates slowly and inhibits the growth of decay organisms in
transit and storage. It may also be applied in the wax. Under certain
conditions it is beneficial to use a combination of these treatments
since all three chemicals are not equally effective against the same
decay organisms.
Citrus fruits, with the exception of lemons, are not generally
stored to the same extent as some deciduous fruits, due in part to the
great number of varieties that are marketed successively over a long
shipping season. The difference in ripening times of the same varieties
in different production areas also extends the availability of freshly
harvested fruit. However, storage is needed and used to provide for
orderly marketing of all varieties and for the extension of the marketing
period for certain fruits. Each type or kind of citrus has specific
environmental requirements; therefore, mixed storage of various citrus
fruits should be avoided.
Florida and Texas-grown Valencia oranges can be stored successfully
for 8 to 12 weeks at 32 to 34°F (0 to 1°C) with a relative humidity of
85 to 90 percent. The same requirements apply to Pope's Summer orange,
a late maturing Valencia-type orange. A temperature range of 40 to 44°F
(5 to 7°C) for 4 to 6 weeks is suggested for California oranges. March-
harvested, Arizona Valencias store best at 48°F (9°C), but June-
harvested fruit stores best at 38°F (3°C).
Oranges lose moisture rapidly, so high humidity should be maintained
in the storage rooms. For storage longer than the usual transit and
distribution periods, 85 to 90 percent relative humidity is recommended.
Florida and Texas oranges are particularly susceptible to stem-end
rots. Citrus fruits from all producing areas are subject to blue and
green mold rot. These decays develop in the packing-house, in transit,
in storage, and in the market, but can be greatly reduced if fruit is
properly treated. Proper temperature is also a very effective method
for reducing decay. However, once storage fruit is removed to room
temperature, decay will develop rapidly.
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Storage of oranges is often complicated by the fact that prolonged
holding at relatively low temperatures may induce the development of
physiological rind disorders not ordinarily encountered at room tem-
perature. Aging, pitting, and watery breakdown are the most prevalent
rind disorders induced by low'storage temperature. Generally,
California and Arizona oranges are more susceptible to low temperature
rind disorders than Florida oranges.
There appear to be no short cuts for successful long storage of
oranges. Harvest at the proper maturity, careful handling of fruit,
good packing-house methods, fungicidal treatments, and prompt storage
after harvest are conducive to long storage life.
Florida and Texas grapefruit is frequently placed in storage for
4 to 6 weeks without serious loss from decay and rind breakdown. The
recommended temperature is 50°F (10°C). A temperature range of 58 to
60°F (14 to 15°C) is recommended for the storage of California and
Arizona grapefruit. A relative humidity of 85 to 90 percent is usually
recommended for the storage rooms in which grapefruit is held. Loss of
weight and loss of water occur rapidly and can be avoided by maintaining
the correct humidity and the additional precaution of a light coating
of wax.
Decay and rind breakdown are deterrents to long storage of grape-
fruit and may develop in fruit during storage or following removal from
storage. Proper prestorage treatments with fungicides, as discussed in
the previous section on disorders and storage temperatures, will greatly
reduce these problems. Also, periodic inspections of the stored fruit
should be made in order to terminate the storage at the very first
symptoms of development of rind pitting or excessive decay.
Extensive studies have been conducted on simulated and accompanied
overseas shipments of Florida grapefruit. Export may require 10 days
to 4 weeks of storage in a refrigerated hold and present problems
similar to those encountered in refrigerated storage. These tests
revealed that Marsh Seedless and Ruby Red grapefruit picked before
January retained appearance best when stored at 60°F (16°C). With
riper fruit, 50 to 55°F (10 to 13°C) is a better storage temperature
range for export shipments. Very ripe fruit harvested in April and
May, however, develop excessive decay following storage at 50 to 60°F
(10 to 16°C).
A large portion of the lemon crop is picked during the period of
least consumption and must be stored until consumer demand justifies
shipment. It is customary for most of this storage to be done near the
producing areas rather, than at the consuming areas. All lemons except
the relatively small percentage that are ripe when harvested must be
conditioned or cured, as well as degreened, before they are shipped.
When market conditions require that the lemons be stored prior to
shipment, the curing and degreening processes proceed during storage.
55
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These lemons are usually stored at 58 to 60°F (14 to 15°C) and 86 to
88 percent relative humidity. Local conditions may require slight
modifications of these conditions.
Lemons picked green but intended for immediate marketing, such as
most lemons grown in the desert portions of Arizona and California,
are degreened and cured at 72 to 78°F (22 to 26°C) and 88 to 90 percent
relative humidity. This may take from 6 to 10 days depending on color
when picked and on the nature of the lemons. The thin-skinned Pryor
strain of Lisbon lemons degreens in about 6 days, whereas the thick-
skinned old-line Lisbon fruit requires as long as 10 days.
Lemon storage rooms must have accurately controlled temperature
and relative humidity; the air should be clean and should be circulated
uniformly to all parts of the room. Ventilation should be sufficient
to remove harmful metabolic products. Air-conditioning equipment is
necessary to provide satisfactory storage conditions, as natural
atmospheric conditions are not suitable for the necessary length of
time. A uniform storage temperature of 58 to 60°F (14 to 15°C) is
important. Fluctuating or low temperatures cause lemons to develop an
undesirable high color or bronzing of the rind. Temperatures of 52°F
and lower cause a staining or darkening of the membranes dividing the
pulp segments and may affect the flavor. Temperatures about 60°F
(15°C) shorten the storage life and are more favorable to the growth
of decay-producing organisms.
A relative humidity of 86 to 88 percent is generally considered
satisfactory for lemon storage, although a slightly lower humidity may
be desirable in some locations. Higher humidities prevent proper curing
of the lemons, encourage mold growth on walls and container, and decay
of the fruit, whereas much lower humidities cause excessive shrinkage.
Proper stacking of the fruit containers in storage rooms is
important to secure uniform air circulation and temperature control.
The stacks should be at least 2 inches (5 cm) apart and the rows 4 inches
(10 cm); trucking aisles at least 6 feet (1.82 m) wide should be pro-
vided at intervals.
Lemons to be stored should be treated with 200 ppm 2,4-D after they
are washed. Lemons that are not washed are sprayed with a solution
of 2,4-D just before they are boxed for storage. Coverage is improved
by adding a few ppm of a wetting agent. This treatment aids in develop-
ment of Alternaria rot, and promotes retention of healthy green buttons.
Unit operations in the citrus industry and their contribution to
pollution are summarized in Table 11.
Utilities needed by fresh citrus fruit processors are electricity,
water, gas, and refrigeration. Water is used in fresh citrus handling
in the washing and rinsing operation, and for the removal of storage
wax on lemons. The hydrocooling method is sometimes used for
56
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TABLE 11. CONTRIBUTION OF CITRUS INDUSTRY UNIT
OPERATIONS TO POLLUTION
Unit operations Water Solids
Orange and grapefruit
Shipping field box to packing house
Dumping to tank X
Washing X X
Rinse X
Inspection X
Drying
Surface coating, coloring X
Grading
Sizing
Stamping
Packaging
Precooling X
Cold storage
Shipping
Lemon
Shipping to packing house
Washing X
Sorting-color grading X
Storage wax application X
Storage (ethylene treatment)
Washing (to remove storage wax) X
Drying
Grading, sizing
Stamping
Packing (by count)
Shipping
Source:
precooling. In the washing water SOPP (sodium phenylphenate) and in the
lemon process for wax removal (shellac, and fungicide), foaming deter-
gents and decay controlling fungicides are usually added. Sunkist
Growers Inc. reported the following typical water usages in their
citrus packing operations:
Naval oranges. Packing 1,200 field boxes/hour, (50-55 Ib each;
22.7-25.0 kg) yielding 1,200 cartons (36-38 Ib each; 16.4-17.2 kg).
Washing requires 350-450 gal/hr (1,300-1,670 liters) of water
and rinsing requires about 500-600 gal/hr (1,890-2,270 liters).
For Valencia oranges (smaller size), the same volume of water
is needed for an hourly run of 1,000-1,100 field boxes.
57
-------
Lemons. Washing requires 350-500 gal/hr (1,300-1,840 liters) for
1,000-1,200 field boxes. Rinsing to remove foam will require the
same amount of water for 1,000 field boxes per hour. Wetting
spray is used before the application of storage wax at a rate of
90 gal/hr (340 liters). A safety rinse of fresh water is used
(5" spray) when the line stops using 20 gallons (76 liters)/hr.
Final rinsing uses 125 gallons (472.5 liters)/hr.
Water used in these packing plants is not recycled, except 50 percent of
the water is recycled from the after-storage wash water.
A
In October 1977, COD from Sunkist orange processing plant effluent
varied from 3,420 to 3,760 ppm; the 24-hour effluent composition from
the lemon plant contained 155 ppm COD.
Chemical oxygen demand.
-------
SECTION 10
CELERY
GENERAL INDUSTRY CHARACTERISTICS
The celery industry is geographically dispersed throughout
California, Florida, Michigan, New York, Ohio, and Washington. Con-
centration of production, however, is in California, which accounts
for approximately 66 percent of total U.S. production, and in Florida,
which accounts for approximately 25 percent. In California the major
producing areas are Ventura and Monterey counties, whereas in Florida
they are Palm Beach, Seminole, and Sarasota counties.
Per capita consumption of celery has remained relatively stable
at 1.0 pound (0.45 kg) during the period 1967 through 1976. Production
during this period has increased from 14.5 million hundredweights to
16.9 million hundredweights, an average annual growth rate of 1.7 per-
cent. During this period, California's share of total production has
increased from 57 percent to 66 percent while Florida's has declined
from 32 percent to 25 percent.
This industry is seasonal in all states except California.
Planting and harvesting dates are shown in Table 12.
TABLE 12. PLANTING AND HARVESTING DATES FOR CELERY
Harvesting dates
State
Planting dates
Begins
Most active
Source: SRI
59
Ends
California
Winter
Spring
Early summer
Late fall
Florida
Winter
Spring
Michigan
New York
Ohio
Washington
Aug
Jan
Apr
Apr
Mar
Apr
Aug -
Nov -
Mar -
May -
1 -
1 -
15 -
10 -
25 -
1 -
Nov
Apr
May
Aug
Dec
Apr
Jul
Jul
Jul
Jul
31
15
31
20
15
15
Nov
Apr
May
Sep
Nov
Apr
Jun
Jul
Jun
Jun
1
1
20
1
1
1
15
10
15
10
Jan
Apr
Jun
Oct
Dec
Apr
Jul
Jul
Jul
Jul
1
15
1
15
1
10
20
1
1
- Mar
- Jun
- Aug
- Dec
- Mar
- May
- Nov
- Oct
- Oct
- Oct
15
15
31
31
31
1
25
31
31
Mar 31
Jul 15
Aug 31
Mar 10
Mar 31
Jul 10
Nov 15
Nov 15
Nov 15
Nov 15
-------
UNIT PROCESSING OPERATIONS
The industry is dependent on unskilled labor for harvesting in both
California and Florida, although mechanical harvesting has been intro-
duced. Several methods of harvesting are used in this industry. In
California, celery is primarily hand-harvested and packed naked in the
field or in wire bound boxes, or sleave wrapped. Prior to sale in some
areas, the crop is also mechanically harvested, then transported to a
central packing shed where it is prepared for sale. Most of the crop
that is mechanically harvested moves into the food processing sector of
the food industry.
After preparation for sale, the produce is stored in vacuum coolers
where buyers select lots.
In Florida, celery production is concentrated in fewer than
12 growers. Acreage and marketing are tightly controlled by a grower
marketing organization. The industry is characterized by large capital
investment in specialized equipment for harvesting and preparation for
shipment. Mechanical and hand harvesting are commonly used on this crop,
as are central packinghouses and in-field mobile packinghouses or "mule
trains." In Florida, at least, celery is also an important crop for
mixed vegetable shipments to end users and the industry operates under
a formal involuntary marketing program through the Florida Celery
Exchange.
Celery may be harvested as soon as it attains proper size. The
celery plants are cut off below the surface of the ground with a sharp
knife, or with a spade. The trimmers follow the cutters, lifting off
the stalk and stripping off the outer leaves.
In the major celery growing areas of Florida and California, the
harvest is at least partially mechanized. The crop is cut from the root
and topped by a one-row harvester, which then elevates the stalks into
a truck or trailer traveling beside the harvester. The celery is then
transported to a stripping unit in the field and onto a field or ware-
house packing system. Most of the trimming is still a hand operation,
but machines that size by weight or diameter and automatic crate or
carton closing machines are widely used to replace manual operations.
Mobile field packing machines are also used to some extent. This
involves manual cutting and placement on extension conveyors, which
move the stalks to a washing unit and then to trimmers and packers on
the moving unit.
After harvesting and stripping, celery is washed with fresh or
chlorinated water to remove soil and trash. Washing may be done in the
field when the celery is packed, but in large operations it is done in
packing sheds, where the celery is inspected for grade.
Various types of crates are used in different areas. The 16-inch
(40 cm) standard crate containing 30 to 36 stalks and weighing 55 to
60
-------
60 pounds (25-27.2 kg) is the most common. It is sold at retail largely
from bulk displays. A limited quantity of celery is prepackaged at
origin in shrink-film sleeves or in open-top plastic bags. These pro-
vide protection from moisture loss and abrasion injury and permit brand
identification.
Packed crates of celery are sprayed with water at 33°F (1°C) and
precooled. Celery can be precooled by refrigerated forced-air cooling,
by hydrocooling, or by vacuum cooling. Hydrocooling is the most common
precooling method; temperatures should be brought to as near 32°F (0°C)
as possible. In practice, temperature reduction is often only to 40
to 45°F (5-8°C). Vacuum cooling is widely used for celery packed in
corrugated cartons for long distance shipment.
After precooling, the crates are then passed down chutes or conveyed
mechanically from the precooling room to refrigerator cars or trucks,
which are usually "blower iced" in warm weather to prevent deterioration.
Open ventilation is sufficient when transporting in cool weather.
Celery may be stored for 4 to 5 weeks at 32°F (0°C) and at 90 to
95 percent relative humidity. Considerable heat is given off due to
respiration, and for this reason the stacks of crates should be separated
to allow circulation under and over the crates and between the bottom
crates and the floor. Forced-air circulation is necessary to avoid
temperature differential between the top and the bottom of the room.
Unit operations and their contribution to pollution are summarized
in Table 13.
Utilities needed by fresh celery processors are water and
refrigeration. Water is used in the field or in central packing opera-
tion to remove soil and trash. Chlorinated water (hypochloride at
50-100 ppm concentration) is used. Some water is used to spray the
packed celery, and cooling is predominantly by hydrocooling, although
air and vacuum cooling are also used.
TABLE 13. CONTRIBUTION OF CELERY INDUSTRY UNIT
OPERATIONS TO POLLUTION
Unit operations Water Solids
Field packing
Trimming X
Washing X
Packing
Spraying X
Cooling X
Storing
Shipping
Source: SRI
61
-------
SECTION 11
LETTUCE
GENERAL INDUSTRY CHARACTERISTICS
Lettuce (Lactuca sativa) is the most important salad crop. It is
grown commercially in at least 20 states and produced for local market
and home use in areas throughout the country. The three most commonly
grown types in the United States are: (1) leaf or bunching type;
(2) head lettuce, including both crisphead and butterhead varieties;
and (3) Cos, or romain type.
Lettuce thrives best at a relatively cool temperature. For this
reason, it is grown principally as an early spring, fall, and winter
crop in the South and Southwest. It is only in the most northern states,
at high altitudes in the West, and near the coast in California, Oregon,
and Washington that it can be grown as a summer crop. Most of the
commercial crop of head lettuce is produced in California (73 percent)
and Arizona (14 percent).
Lettuce is the second most important vegetable crop behind tomatoes
in California and the most important vegetable fresh crop to that state.
The two major producing areas are Monterey, which produces approximately
39 percent, and the Imperial Valley, producing approximately 31 percent.
Important secondary producing areas are Riverside, Fresno, Santa Barbara,
and San Luis Obispo.
Per capita consumption of lettuce has increased steadily from
22.1 pounds (9-5 kg) in 1967 to 24.3 pounds (11.0 kg) in 1976. Pro-
duction during this period has increased from 42.4 million hundredweight
to 53.9 million hundredweight, an average annual growth rate of
1.3 percent.
This industry is seasonally oriented in all commercially producing
states except California. Planting and harvesting dates for the major
producing states are shown in Table 14.
UNIT PROCESSING OPERATIONS
Without exception, the industry is highly dependent on unskilled
labor for harvesting in each of the producing states. Harvesting of
lettuce is by hand, on a selective harvest basis. Commonly about one-
third of a given crop is cut at first harvest, with two or three
successive cuttings, depending on market and weather conditions.
62
-------
TABLE 14. PLANTING AND HARVESTING DATES FOR LETTUCE
Harvesting dates
State
Planting dates
Begins
Most active
Ends
California
Winter
Early spring
Summer
Early fall
Arizona
Winter
Early spring
Late fall
Florida
Colorado
New Mexico
Spring
Fall
Sep -
Nov -
Mar -
Jun -
Aug 15 -
Nov 1 -
Jul 20 -
Aug 25 -
Mar 20 -
Jan 1 -
Aug 1 -
Dec
Feb
Jun
Sep
Dec
Feb
Sep
Mar
Jul
Jan
Aug
1
1
15
15
30
10
15
15
Nov
Mar
Jun
Sep
Nov
Mar
Sep
Oct
Jul
Apr
Oct
15
1
1
1
1
10
15
31
1
25
15
Jan
Apr
Jun
Sep
Dec
Apr
Oct
Nov
Jul
May
Oct
1 -
15 -
1 -
1 -
1 -
15 -
15 -
15 -
15 -
1 -
10 -
Feb
May
Aug
Nov
Mar
Apr
Dec
May
Sep
May
Oct
28
31
1
15
31
25
15
15
20
31
31
Apr
May
Aug
Dec
Jun
Jun
Jan
Jun
Oct
Jun
Nov
30
31
31
15
20
20
25
25
31
5
10
Source:
Head lettuce is commonly cut at or just below the surface of the
ground, and all soiled and diseased leaves are removed before packing.
Essentially all of the crop is now packed in cartons (1% to 2%
dozen heads), usually in the field, but if a plastic film wrap is used
it may be wrapped and packed in the field or shed. Wrapping of
individual heads of lettuce at shipping point for marketing increased
quite rapidly in the early 1960s but has leveled off in recent years.
Approximately 25 percent of the crop is now individually wrapped.
Wrapping of the trimmed heads is done either in the field on traveling
packing units or in the packing house where somewhat more sophisticated
equipment is available. Most of the wrapping is done with shrink films,
which cling very tightly to the head after heating.
A considerable amount of lettuce wrapping is also done at terminal
repacking facilities. The advantages of origin wrapping are labor and
freight charge savings, whereas terminal trimming and packaging gives
a fresher product at retail.
Oriented polystyrene has been generally favored as a shrink wrap,
primarily because of its permeability for respiratory gases and water
vapor.
A marked change has taken place in the methods of harvesting and
packing lettuce in the large producing areas of California and Arizona.
63
-------
This change was brought about by the use of the vacuum cooling process.
This process eliminated the need for direct icing and made it feasible
to use corrugated paperboard cartons instead of wooden crates. This
also moved the site for packing from the sheds to the field. Practically
all of the lettuce crop from the Salinas-California district is field-
packed and vacuum cooled. The cartons are mechanically placed in the
precooling chambers. As much as half a carload can be handled at one
time and the temperatures at the centers of the heads can be reduced
to 34°F (2°C) in less than 30 minutes. The cooled cartons are placed
in precooled refrigerator cars and trucks for shipment to market.
Lettuce may be kept in cold storage at 32°F (0°C) and high relative
humidity for 2 to 3 weeks after harvest. However, it is highly perish-
able. For minimal deterioration, lettuce must be kept at a temperature
as close to its freezing point as possible without actually freezing
it. Lettuce will keep about twice as long at 32°F (0°C) as at 38°F
(3°C). Most lettuce is now packed in cartons and vacuum-cooled to near
33°F (1°C) soon after harvest. It should then be immediately loaded
into refrigerated cars or trailers for shipment.
Russet spotting, which occasionally causes serious losses, is
usually not extensive at temperatures below 35°F (1°C). Lettuce should
not be stored with apples, pears, cantaloupes, or other products that
give off ethylene, as this gas increases russet spotting. Hard lettuce
is more susceptible to this disorder than firm lettuce. Storage or
shipment in low oxygen atmosphere (1 to 8 percent) is an effective
method of controlling russet spotting. An increasing quantity of
lettuce is shipped in modified atmospheres to aid quality retention.
Modified atmospheres are a supplement to proper transit refrigeration,
but are not a substitute for refrigeration. Lettuce is not tolerant
to carbon dioxide and is injured by concentrations of 4 to 5 percent or
higher.
Unit operations and their contribution to pollution are summarized
in Table 15.
The utility needed by fresh lettuce processors is refrigeration.
Water is not used in fresh lettuce handling.
TABLE 15. CONTRIBUTION OF LETTUCE INDUSTRY UNIT
OPERATIONS TO POLLUTION
Unit operation Water Solid
Trimming X
Packing (wrapping)
Vacuum cooling
Cold storage
Shipping
Source: SRI
-------
SECTION 12
MELONS
Two types of melons were considered in this study—watermelons and
cantaloupes or muskmelons. The muskmelon (Cucumos melo) is frequently
referred to as cantaloupe by the trade. The Southwest is particularly
suited to melon culture, but favorable conditions prevail in many other
sections of the country, making it possible to grow the crop for local
market. The leading areas for growing cantaloupes are California,
Arizona, Texas, Georgia, South Carolina, Michigan, Indiana, North
Carolina, Colorado, Florida, Ohio, and Maryland. The growing areas
studied were Florida for watermelons and California for cantaloupes.
FLORIDA WATERMELONS
General Industry Characteristics
Watermelons (Citrullus vulgaris) are commercially produced in 16
states of the contiguous United States: Florida accounts for approxi-
mately 38 percent of production; Texas, approximately 17 percent;
Georgia, approximately 9 percent; and California, approximately 7 per-
cent. In Florida, production as a percentage of total U.S. production
has increased from less than 20 percent in 1949 to its current share.
The reasons for this increase include (1) an increase in yields per
acre of approximately 86 percent versus a U.S. average of 43 percent,
(2) use of "new land" areas, particularly in South Florida, and (3) the
ready availability of water systems for irrigation. Commercial
production in that state covers a wider area and greater number of
acres than any other individual vegetable crop.
Per capita consumption of watermelons in the United States has
decreased from 14.2 pounds (6.45 kg) in 1967 to 13.6 pounds (6.17 kg)
in 1976. During this period, production has declined from 26.9 million
hundredweight to 26.2 million hundredweight, an average annual decrease
of 0.3 percent.
This industry is seasonal in nature (summer/spring); planting and
harvesting dates in the four major producing states are shown in
Table 16.
Unit Processing Operations
The watermelon industry is very dependent on skilled and semiskilled
labor for harvesting. Multiple harvests are necessary with this crop.
Watermelons that have been selected as being properly mature are cut
65
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TABLE 16. PLANTING AND HARVESTING DATES FOR WATERMELON
Usual harvesting dates
State Planting dates Begins Most active Ends
Florida
Texas
Georgia
California
Late spring
Early summer
Nov 15 -
Jan
Mar
15 -
1 -
Nov -
Mar -
Mar
Jun
Apr
Mar
Jun
31
1
15
Mar
May
Jun
May
Jun
20
10
15
25
25
May
Jun
Jun
Jun
Jul
1
1
25
10
1
- Jun
- Aug
- Aug
- Jul
- Aug
30
31
15
20
31
Jul 1
Oct 15
Sep 15
Jul 31
Oct 15
Source: SRI
from the vines and may be windrowed or placed directly into a field
truck for hauling to a loading area of the field or to a packing shed.
Here they are sorted to remove those with insect or disease damage or
those bruised or broken in handling. Sizing by weight classes is done
by visual inspection or in some cases by automatic sizing on a conveyor
system. A few melons move to market by piggyback trailers but mostly
they are transported by truck.
Southern-grown watermelons generally are shipped north. Large
quantities of watermelons are shipped in refrigerated or vent-cooled
trucks or railroad cars. Usually, they are shipped in bulk; more than
80 percent are moved by truck, and the remainder is shipped by rail for
long distances.
Cold storage is seldom used for most kinds of melons except to
avoid temporarily adverse market conditions. To avoid injury by chilling,
most melons are stored at 45 to 50°F (7-10°C) with 85 to 90 percent
humidity.
U.S. standards are available but are not used for grading or for
shipping point inspection. Quality is determined on the basis of
appearance, size, seed and flesh color, and other internal characteris-
tics of cut samples. Cut melons account for approximately 75 percent
of sales through retailers, as retailers attempt to minimize effects
of over- and undermature fruit at harvest and physical damage during
handling. Compositional characteristics such as moisture and sugar
content are important aspects of quality but are not used as a measure
or standard of quality.
66
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CALIFORNIA CANTALOUPES
General Industry Characteristics
About 76 percent of the United States supply of cantaloupes is
grown in California and Arizona. Texas production accounts for about
14 percent, with the remainder being grown in the north central and
southeastern states.
Unit Processing Operations
Cantaloupes are commonly harvested from 10 to 20 times from any one
field during the season. Harvesting is entirely by hand labor. The
pickers must be skilled in selection of melons for harvest, as selection
is based on size, ground color, and ease of separation from stem. They
are usually put into bags carried on the back or side of the laborer.
When 60 or 70 pounds (27 or 32 kg) of melons are in the bag, the picker
carries it to the field truck or trailer for emptying.
At the packing plant, the trucks are unloaded mechanically into
an accumulator bin, where the melons are sorted and graded. Most plants
are highly mechanized with automatic sizing equipment that determines
the size on a weight or volumetric basis. The melons are washed and
hydrocooled to about 40°F (5°C). About 85 percent of the melons are
packed in cartons and palletized. They are stored in cool rooms until
shipped to the wholesale markets.
Harvest aids for cantaloupes are used in some of the more concentrated
production areas. As the mobile field packing machine moves through the
field, it can cover 10 to 20 beds by means of conveyors extending from
each side of the packing unit. Pickers select mature fruits and place
them in a packing area on the machine; after packing, the filled cartons
or crates are loaded onto a following truck for transport to the pre-
cooling and loading shed.
Although types of containers and methods of packing vary consider-
ably, practices have been standardized in most commercial operations of
the West. Crates are primarily used for shipping long distances.
Cantaloupes harvested at the hard stage (less than full slip) can
be stored about 15 days at 36 to 40°F (2-5°C). Lower temperatures may
cause chilling injury. Full slip cantaloupes can be held 5 to 14 days
at 32 to 35°F (1-2°C). Cantaloupes are sometimes hydrocooled or pre-
cooled with top ice before shipment. Watermelons are best stored at
40 to 50°F (5-10°C) and should keep from 2 to 3 weeks. Watermelons
decay less at 32°F (0°C) than at 40°F (5°C), but they tend^to become
pitted and have an objectionable flavor after 1 week at 32°F (0 C).
The trend in the industry is toward integrated operations consisting
of private companies that grow, pack, ship, and market their melons.
67
-------
The marketing may be done by their own sales desk or through sales
agents. Equally important are cooperatives owned by growers that
perform the same functions as the private concerns. The trend is away
from independent growers and packer-shippers.
Unit operations and their contribution to pollution are summarized
in Table 17.
TABLE 17. CONTRIBUTION OF WATERMELON AND CANTALOUPE INDUSTRY
UNIT OPERATIONS TO POLLUTION
Unit operation Water Solids
Watermelon
Inspection X
Sizing
Cold storage (occasionally)
Shipping (bulk)
Cantaloupe
Sorting X
Grading, sizing
Washing X
Surface coating
Hydrocooling X
Packing
Storing
Shipping
Source: SRI
Utilities needed by fresh melon processors are water and refrigera-
tion. Water is used in cantaloupe handling only for washing in the
field if necessary and for hydrocooling prior to shipment. Surface
coating spray used for cantaloupe treatment is a 4 percent oxidized
polyethylene solution.
68
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SECTION 13
ONIONS
GENERAL INDUSTRY CHARACTERISTICS
Onions (Allium cepa) are grown in 17 states; California is the
largest producer, accounting for 25 percent of the total. Texas,
Oregon, New York, and Idaho combined account for 50 percent of total
U.S. production. There are two seasons for onions, spring onions in
Arizona, California, and Texas, and summer onions in all producing
states except Arizona.
Total production of onions (excluding green onions) has increased
from 1.4 million tons in 1967 to 1.8 million tons in 1976. The produc-
tion data include onions produced for processing, (e.g., dehydration,
frozen, canned). It is estimated that per capita consumption of
onions used as fresh produce has not increased in recent years.
UNIT PROCESSING OPERATIONS
Operations performed in getting an onion crop from the field to the
consumer include:
(1) The onions are undercut or hand-pulled and allowed to dry
for a period of 5 to 10 days before topping.
(2) The bulbs are topped by hand or machine and placed in burlap
bags for further curing in the field.
(3) The bagged onions are loaded onto trucks and hauled to a
building for storage or immediate packing for the market.
These operations vary from district to district, but, in general,
practices that are found most suitable for a region are followed there
rather consistently. Harvesting and curing are frequently quite dis-
tinct, especially when the bulbs are cured artificially, but they may
be continuous or simultaneous operations in the field.
Onions may be harvested either as green-bunch onions or as mature
bulbs. An onion is suitable for green bunching from the time it has
reached pencil size until it begins to bulb. Such immature onions are
commonly harvested in home and market gardens. In the large onion-
growing districts, the crop is harvested almost entirely at the mature
stage.
69
-------
Harvesting may begin when the tops start to fall over. The exact
time of harvest varies with environmental conditions. In the West and
South it should begin during warm weather, when approximately 25 percent
of the tops are down. Under cooler weather conditions, harvesting is
usually delayed until 50 percent are down. In the East it does not
usually begin until most of the tops are down.
A small onion plow is frequently used to loosen the bulbs. In
many soils, bulbs are easily pulled by hand. In irrigated sections
water may be used to soften the ground a day or two before harvesting.
The pulled onions are thrown into windrows with the bulbs being shaded
by the tops to minimize sunscald.
Some fall onions are now harvested mechanically by one of several
methods, including the mechanical potato harvester, a combination
harvester that incorporates pinch roll equipment to remove tops, and a
harvester that includes an air blast to raise the tops so that rotating
knives can cut them. However, the use of mechanical harvesters and
bulk bins or trucks is limited to those areas and operators who have
facilities for curing the onions after removal from the field.
A period of curing usually follows the harvest. In the South and
West, curing is usually accomplished in a few days, but in the North
the curing period may take 3 to 4 weeks depending upon climatic
conditions. In Texas, onions are often pulled, clipped, and shipped
the same day- Care should be taken to avoid sunscalding caused by curing
too long in direct sunlight.
Tops are usually removed after they are well dried down. The tops
may be cut by hand with shears, or by a topping machine. One-half to
one inch of the top is usually left on the bulbs to prevent entrance
of disease organisms.
Several methods of artificial curing have been tried, but the method
most commonly used for early onions involves blowing heated air (110-
115°F or 43-46°C) vertically through a grill on which the onions in mesh
bags have been placed. Such treatment continued for a period of 8 to
12 hours usually provides satisfactory curing for either immediate
shipment to market or storage for later sale.
' Some tests with onions grown in South Texas showed that direct
exposure to gas-fired infrared radiation for a period of 6 minutes gave
better control of neck rot in freshly harvested onions than forced-air
curing. However, there has been no commercial use of the gas-fired
curing system.
After the tops have been removed, the onions are cleaned and
graded.
A comparatively low humidity is essential in the successful storage
of dry onions. At humidities higher than those at which most other
70
-------
vegetables keep best, onions are disposed to root growth and decay;
at too high temperature sprouting is encouraged. Storage at 32°F (0°C)
with a relative humidity of 65 to 70 percent is recommended to keep
them dormant.
Onions are stored in 50-pound (22.8 kg) bags, in crates, in pallet
boxes that hold about a half ton of loose onions, or in bulk bins. Bags
of onions are frequently stored on pallets. Bagged onions should be
stacked to allow proper air circulation. Modern air-cooled storages
have forced ventilation systems. Air is introduced through floor racks
beneath the bins of onions. The air can be heated if necessary. Onions
in bins are stored about 10 feet (3 meters) deep. Soft onions at the
bottom of the bin might be distorted in shape when stored in this manner.
Onions should not be stored with other products that tend to absorb
odors.
When onions are removed from storage in warm weather, they are apt
to sweat because of moisture condensation. This may favor decay. Warm-
ing onions gradually should avoid this difficulty.
In the northern onion-growing states, onions of the globe type are
generally held in common storage, since average winter temperatures are
sufficiently low to permit common storage. They should not be held after
early March unless they have been treated with maleic hydrazide in the
field to reduce sprout growth.
Refrigerated storage is often used to hold onions for marketing
late in the spring. Onions to be held in cold storage should be placed
there immediately after curing. A temperature of 32°F (0°C) will keep
onions dormant and reasonably free from decay, provided the onions are
sound and well cured when stored. Sprout growth indicates too high a
storage temperature, poorly cured bulbs, or immature bulbs. Root
growth indicates too high a humidity.
Globe onions can be held'for 6 to 8 months at 32°F (0°C). Mild,
or Bermuda, types can usually be held at 32°F (0°C) for only 1 to 2 months.
Onions of the Spanish type are often stored; if well matured, they can be
held at 32°F (0°C), at least until January or February. In California,
onions of the sweet Spanish type are held at 32°F (0°C) until April or
May-
Onions are damaged by freezing, which appears as water-soaking of
the scales when the onions are cut after thawing. Onions that have
been slightly frozen may recover with little perceptible injury if
allowed to thaw slowly and without handling.
Onion sets, the small dry onions that are used as planting stock
for production of early green onions, require practically the same
temperature and humidity conditions as onions, but since they are
smaller in size they tend to pack more solidly. They are handled in
71
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approximately 25-pound (11.4 kg) bags and should be stacked to allow
the maximum air circulation.
Green onions (scallions) and green shallots are usually marketed
promptly after harvest. They can be stored 2 to 3 weeks at 32°F (0°C)
with 90 to 95 percent relative humidity. Crushed ice spread over the
onions will aid in supplying moisture. Packaging in polyethylene film
will also aid in preventing moisture loss.
The onion industry unit operations and their contribution to
pollution are summarized in Table 18.
TABLE 18. CONTRIBUTION OF ONION INDUSTRY UNIT OPERATIONS TO POLLUTION
Unit operations Water Solids
Field drying
Topping X
Curing
Cleaning, grading X
Storage
Packaging
Shipping
Source: SRI
Utilities needed by fresh onion processors are gas, electricity,
and refrigeration. Water is not used in fresh onion handling.
Air pollution in the form of unpleasant odors near the curing
operation is the only potential problem with this crop.
72
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SECTION 14
POTATOES
GENERAL INDUSTRY CHARACTERISTICS
The potato (Solanum tuberosum) is by far the most important
vegetable in terms of quantities produced and consumed. Potatoes are
grown commercially and for home use throughout the United States and
lead all vegetables in terms of acreage used and value produced.
Although the importance of this basic food crop has declined over the
years, it remains the principal vegetable.
In most of the 40 states where potatoes are grown, production
caters to local and regional markets only. Those states where shipments
move outside local and regional markets include California, Idaho,
Maine, New York, and Washington. Of these, California is the largest
interstate shipper of fresh potatoes, followed by Idaho.
Two varieties form the bulk of fresh potato production and ship-
ment. These are the round white produced in California, Maine, and
New York, and the russet in Idaho and Washington.
Potatoes of the early crop seldom reach full maturity, on account
of dry warm weather, early blight, tip-burn, and other conditions that
interfere with normal growth. Consequently, the plants usually begin to
die down before the crop is mature, even though good culture has been
given and a spray schedule has been followed. As this stage approaches,
harvesting must be initiated.
Although the harvesting time for late potatoes is determined
primarily by maturity of the crop, other considerations such as market
prospects, availability of help, and weather conditions may be influenc-
ing factors. The vines should mature and die before harvest so the skins
of the tubers will set and thus decrease the likelihood of skinning
and bruising. When necessary, the vines are killed by applying dinitro
compound and ammonium sulfate spray.
Commercial application of mechanized potato harvest began about
1950. Today harvest is almost completely mechanized in all of the major
producing areas.
The industry is seasonal in nature with most producing areas
oriented to fall harvesting. Planting and harvesting dates for the
major producing states for fresh potatoes are given in Table 19.
73
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TABLE 19. PLANTING AND HARVESTING DATES FOR POTATOES
Usual harvesting date
State
Planting date
Begins
Most active
Ends
California
Winter
Late spring
Early summer
Late summer
Fall
Idaho
Maine
New York
Upstate
Long Island
Washington
Jun
Nov
Feb
Mar
May
Apr 15
May 10
Apr 25
Mar 20
Feb 15
- Sep
- Mar
- Apr
- Jun
- Jun
- Jun
- Jun
- Jun
- Apr
- May
15
15
15
30
1
Nov
Apr
Jun
Jul
Sep
Sep
Aug
Aug
Jul
Jul
20
15
15
15
10
10
25
10
10
10
Dec
May
Jul
Aug
Oct
1
1
1
1
1
Sep
Sep
Sep
Aug
Aug
15
1
15
1
- Mar
- Jul
- Aug
- Sep
- Oct
and Oct
- Oct
- Oct
- Oct
- Nov
31
31
15
30
31
10
30
31
1
Apr
Aug
Aug
Oct
Mar
Oct
Oct
Nov
Nov
Nov
20
15
25
15
31
15
20
15
15
15
Source: SRI
Per capita consumption has declined from 62.0 pounds (28 kg) in
1967 to 56.8 pounds (25.8 kg) in 1976. During this period production
has also fallen from 175.8 million hundredweight to 159.0 million
hundredweight, an average annual decrease of 1.0 percent.
UNIT PROCESSING OPERATIONS
Harvesting equipment comes in one-, two-, or four-row sizes with
conventional diggers, rod conveyors, dirt and vine eliminators, and
cross and extension conveyors for transfer of the tubers to the accompany-
ing bulk trucks. Most of the larger harvesters provide space on the
machine for several sorters so that obvious culls, clods, and stones
can be disposed of before the tubers move to the bulk hopper or dump-
trucks. Some have special equipment for separation of tubers from
stones and clods.
Early crop potatoes are usually not stored except during congested
periods. They are most perishable and cannot be expected to keep as well
or as long as late crop tubers. Refrigerated storage at 40°F (5°C)
following curing period of a few days at 70°F (21°C) is recommended, or
they can be stored for about 2 months at 50°F (10°C) without curing.
Late crop potatoes produced in the northern half of the United
States are usually stored. The greater part of the crop is held in non-
refrigerated commercial and farm storages, but some potatoes are held
in refrigerated storages. Potatoes in nonrefrigerated storages usually
are held in bulk bins 8 to 20 feet (2.4 to 6.1 meters) deep. Shallower
-------
bins are used in the milder climates. Some potatoes are stored in
pallet boxes. In refrigerated warehouses, potatoes can be stored in
sacks, pallet boxes, or bulk.
Late crop potatoes should be cured immediately after harvest by
holding them at 45 to 60°F (7 to 16°C) and 90 to 95 percent relative
humidity for about 10 to 14 days. This will permit tuberization and
wound periderm formation (healing of cuts and bruises). If properly
cured, they should keep in sound dormant condition at 38 to 40°F (4 to
5°C) with 90 percent humidity for 5 to 8 months. A temperature below
this is not desirable except for seed stock for late planting. For
this purpose, 38°F (4°C) is best. At 40°F (5°C) or below, Irish potatoes
tend to become sweet. For ordinary table use, potatoes held at 40°F
(5°C) are satisfactory but they probably would be unsatisfactory for
chipping or French frying without being desugared or conditioned at
about 70°F (21°C) for 1 to 3 weeks previous to'use. Potatoes will remain
dormant at 50°F (10°C) for 2 to 4 months. Since tubers held at this
temperature are more desirable for both table use and processing than
those from 40°F (5°C) , it is recommended that late crop potatoes for
use within 4 months be stored at 50°F (10°G) and those for later use be
stored at 40°F (5°C). All potatoes should be stored in the dark to
prevent greening. They should not be kept in the same room with fruits,
nuts, eggs, or dairy products because of the objectionable flavor they
may impart.
Minimum shrinkage and best quality potatoes result if the relative
humidity is maintained near 90 percent or slightly higher. Condensa-
tion on the ceiling and resultant moisture drip is sometimes a problem
when very high humidity is maintained.
Potatoes usually do not sprout until 2 to 3 months after harvest
even at 50 to 60°F (10-15°C). However, after 2 to 3 months storage,
sprouting can be expected in potatoes stored at temperatures above
40°F (5°C) and particularly at temperatures around 60°F (15°C). Although
limited sprouting does not affect potatoes for food purposes, badly
sprouted stock shrivels and is difficult to handle and market. Certain
growth regulating chemicals have been approved by the U.S. Food and
Drug Administration to control or reduce sprouting on potatoes. One
of these, maleic hydrazide, is applied to the plants in the "field 2 to
4 weeks before harvest. Another chemical extensively used is CIPC
(isopropyl-N-(3-chlorophenyl)carbamate), which is applied to the
potatoes after harvest, usually after a period in storage to avoid
interference with wound healing. CIPC can also be applied as the
potatoes are removed from storage to control sprouting during marketing.
Ventilation or air circulation in potato storage is needed to
provide and maintain optimum conditions throughout the storage. In
northern states, where average outdoor temperatures during storage are
low, little circulation or ventilation is needed. Shell or perimeter
circulation is extensively used in these areas for seed and table stock
-------
potatoes. Forced circulation through the potatoes is required for the
higher temperature storage of processing potatoes and for table and seed
stock in the warmer parts of the late crop area. Rapid air circulation
may lower the relative humidity of the air immediately surrounding the
potatoes; it is conducive to drying and weight loss, which may be
desirable if there are disease problems but undesirable with sound
potatoes because of increased shrinkage.
Potatoes are usually marketed in mixed sizes with only very small
and extra large tubers eliminated. Weight sizers are used sometimes,
principally for long cultivars of potatoes and, particularly for count
packs of baking potatoes for restaurant and institutional trade.
Until rather recently almost all potatoes were shipped to market
in burlap bags holding 100 pounds (45 kg) net. The present trend is to
smaller containers, which can be more easily handled during loading,
unloading, and at the terminal markets. Bags holding 50 pounds
(22.5 kg) are increasingly used for shipment, and cartons containing
50 pounds (22.5 kg) net are popular, particularly for the fancier pecks
of sized potatoes.
Potatoes are usually prepacked for retail sale. Kraft paper bags,
often filled for 5 or 10 pound (2.25-4.5 kg) weights in the back room
of the grocery store, were widely used before prepacking developed.
Plastic film bags are used since the knowledge of film ventilation has
been developed. This provides an adequate number of holes, so that
proper relative humidity can be maintained in the bags. Ventilated
polyethylene bags are now widely used for 5- and 10-pound (2.25 and
4.5 kg) consumer packs. However, mesh and paper bags retain a sub-
stantial part of the prepackage business.
The 10- and 25-pound (4.5 and 11.25 kg) packs in paper or mesh are
often handled and loaded individually, whereas 5- and 10-pound (2.25
and 4.5 kg) packs in polyethylene bags are usually packed in multiwall
paper master containers for shipment.
Unit operations and their contribution to pollution are summarized
in Table 20.
Utilities needed by fresh potato processors are water, electricity,
and refrigeration. Water is used in fresh potato handling in wet dump
tank and in the water flume and in occasional washing (only when the
crop is very dirty). The flume water is occasionally chlorinated
(80-100 ppm hypochlorite solution) and most flume water is recycled.
All fresh potato shippers in the State of Idaho water-flume their
products. Average water usage for the five largest shippers in 1977
was 4.58 gallons per hundredweight (45 kg) with a range of 3 to
6 gallons per hundredweight. One smaller shipper in Idaho reported
76
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water use at a rate of 10 gallons per hundredweight. These figures
include all water used in the operation (calculated as
water meter reading^
package weight '
TABLE 20. CONTRIBUTION OF POTATO INDUSTRY UNIT
OPERATIONS TO POLLUTION
Unit operations
Water
Solids
Water flume
Washing (occasional)
Size sorting (optional)
Inspecting
Curing
Storage
Packaging
Shipping
X
X
X
X
Source: SRI
77
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SECTION 15
SHELL EGGS
GENERAL INDUSTRY CHARACTERISTICS
The number of eggs produced for the fresh egg market and for
processing has been declining. In 1967 about 70 billion eggs were
produced and by 1976 production had declined to about 65 billion. Per
capita consumption of in-shell eggs (fresh market) during the period
declined from 285 eggs to 243 eggs. This trend, in part, is a reflection
of the reduction in home baking and an increase in use of convenience
foods, the increased use of egg substitutes by food processors, and the
increase in consumer health concerns (e.g., cholesterol).
Eggs are produced in each of the 50 states; however, 51 percent of
the eggs are produced in 8 states, with California accounting for
14 percent of production; Georgia, 9 percent; Arkansas, 6 percent;
Alabama and Pennsylvania, 5 percent each; and Florida, North Carolina,
and Indiana, 5 percent each.
The egg marketing industry (fresh eggs) consists of assembler-
packers, of eggs who obtain their eggs from the producer and then cool,
wash, disinfect, grade, pack, and market the eggs to distributors,
retailers, institutional outlets, and the egg products industry.
Figure 7 shows the distribution patterns.
Although there are still large numbers of producers and assemblers,
the industry has slowed down in growth. Large producers and assemblers,
and many vertically integrated companies or cooperatives, are beginning
to dominate the market.
The production of eggs has become highly specialized, and the
trend is toward large-scale egg production farms, many of which have
more than 20,000 birds. Farms with over 100,000 laying hens are not
uncommon in any of the major producing states. Because eggs are the
major source of income on such farms, emphasis is given to producing
and marketing eggs of high quality. Seasonal peaks in production have
virtually disappeared and the hatching of laying stock chicks is a year-
round business. Monthly production now fluctuates less than 10 percent
above or below the monthly average. Long-term cold storage of eggs has
therefore virtually disappeared.
Today's commercial egg industry in the United States is dominated
by the Single Comb White Leghorn. This breed has found favor because of
-------
Farm Product
Commodity Merchandising
Primary Processing
Refining/Preserving
Food Manufacturing
Fabrication
Food
Merchandising
Comnerclal
Egg
Producer
Bakers
Confectioners
Premlx fabricators
Baby Food
Noodles and Macronl
Mayonnaise
Salad Dressing
Ice Cream
Other
Figure 7. Egg marketing channels.
-------
its high rate of lay, early maturity, good feeding efficiency, relatively
small body size, and adaptability to diverse climates. Furthermore,
leghorns lay eggs with white shell, the most widely demanded shell color
among consumers.
Day length influences the rate of egg production. Diminishing day
length retards sexual maturity in young pullets, and increasing length
of day tends to stimulate egg production in layers. This physiological
phenomenon is utilized by keeping the birds in light-tight lay houses,
and time clocks are used to gradually lengthen the daily exposure to
artificial light. A day length of 14 to 16 hours is commonly used at
an intensity of 3/4 to 1 foot-candle.
UNIT PROCESSING OPERATIONS
The criteria usually used in evaluating egg quality are: appearance,
odor and flavor, nutritive value, culinary value, and microbiological
condition.
The quality of eggs is affected by the management of the poultry
flocks (selection of birds, feeding well-balanced rations, keeping the
flock disease free by good sanitation and vaccination, replacing the
flock before an excessive decline in egg quality occurs) and the way
the eggs are handled before they are marketed.
For market purposes, eggs should be infertile. Such eggs are
produced by removing the male birds from the flock.
The problem of dirty or soiled eggs is largely one for the producer
to solve. To produce clean eggs, it is desirable that the laying flock
be kept confined to the house or confined until the laying has been
completed for the day- Dry floor litter is used to reduce the number
of dirty eggs. Chopped straw, woodshavings, oat hulls, chopped corncobs
or cornstalks, and sawdust are used as litter. Nests are also maintained
in sanitary conditions by using nesting materials such as shavings,
rice hulls, oat hulls, and sawdust.
Some eggs will be soiled and will require cleaning even when laying
houses and nests are kept clean. Dry buffing with emery paper or a
similar abrasive is the best method for the smaller producer. Washing
becomes necessary when eggs are so dirty that buffing results in an
unattractive or damaged shell. However, washed eggs must be used
immediately. Dirty eggs may be soaked in detergent solution for
3 minutes at 120°F (49°C) and then rinsed off in clean running water.
Eggs must be dried immediately after the washing process.
Eggs are usually collected at least three times a day to reduce
heat deterioration and soiling. A process diagram for shell eggs is
shown in Figure 8. Wire baskets are used for gathering of the eggs.
Cooling eggs in wire baskets is a desirable practice. As the eggs are
80
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INEDIBLE EGGS
i_INEDIBLE EGGS
"*~
„ ThtFniiu F Fftfis —
1
RECEIVING COOLER
i
MACHINE LOADING
*
WASHING
»
OILING
1
CANDLING
J
GRADING
*
PACKING - ONE
DOZEN CARTONS
1
PACKING - SHIPPING
CASES
1
OUT GOING
COOLER
CLEANUP J
CONTINUOUS DVER-^j
FLOW AND DUMPING
CLEANUP __,
|
CLEANUP _.
n
,
SOLID
WASTE
WASTEWATER
SA-5619-59
Figure 8. Shell egg process flow diagram.
81
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gathered, they are put, basket and all, in a cool, humid place to
maintain their quality and to prevent evaporation. For cooling eggs
temperatures between 45 and 55°F (7 and 13°C) and 70 percent relative
humidity are recommended.
Eggs are sorted for inferior quality by candling and for size by
weighing. Most states have egg grading laws; some are mandatory, and
others are permissive. The USDA carries out a cooperative federal-state
egg grading program that provides supervision of the grading operation
by federal personnel. The grading factors include quality factors (AA,
A, B, C quality grades depending on quality factors of the shell, air
cell, yolk, and white) and weight classification (jumbo, extra large,
large, medium, small, peewee, based on ounce weight per dozen).
Mechanization is replacing hand candling, grading, and packing.
Eggs are conveyed over lights for visual examination, transferred to
mechanical weighing devices, and automatically packed according to
quality and size.
Refrigeration is the most common means of preserving the quality
in shell eggs. The use of mechanical refrigeration in the cooling and
holding of eggs on the farm has become common.
Temperature and carbon dioxide play very important roles in
preventing changes in the appearance of eggs during storage. The
temperature should be as low as possible without freezing (29 to 30°F
or -2 to 1°C) if eggs are to be kept for extended time. Temperatures
this low are seldom used today because of the short marketing channels.
For short-term storage (few days), 50 to 60°F (10 to 16°C) tem-
perature is satisfactory.
The most common container used in packaging eggs for shipment is
the 30-dozen egg case. Fiber, wooden, and wire-bound cases are avail-
able in this size.
Filler flats and 2x6 inch cartons that hold two rows of 6 eggs
each are also used. A regular filler flat for eggs is a tray having
30 individual cells arranged in five rows of 6 cells each. Normally,
in regular 30-dozen egg cases, 10 regular fillers and 12 regular flats,
or 30 regular 2x6 inch egg cartons with a flat on the top or bottom
of the case are used.
A problem of increasing seriousness for poultrymen is the handling
and disposal of waste materials, particularly where long-established
production units have become surrounded by expanding urban housing.
Poultry droppings have some fertilizer value, but costs of removal,
hauling, and spreading the droppings on crop land often exceed the
costs of the same nutrients supplied by commercial inorganic fertilizers.
A limited amount of processing of poultry manure is being done in which
82
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composting is accelerated, and the resulting dry, nonodorous product
finds an outlet in nursery and home garden use. However, manure dis-
posal is rapidly becoming a cost factor rather than a source of income.
Where droppings are accumulated within the poultry house or on the floor
for periodic removal, care must be taken to prevent fly breeding
Adequate ventilation is important to rapidly lower the moisture content
of the droppings below the level at which maggots can develop. Screening
of open-type houses and the inlets of environmental houses is effective.
The use of chemical pesticides for fly control should be limited to
emergency situations. Improper management of poultry wastes can also
result in production of obnoxious odors. Ammonia fumes not only
irritate workers but cause birds to be more susceptible to respiratory
infections; also, eggs exposed to ammonia lose albumen quality at a more
rapid rate.
The principal input materials for shell egg processing are eggs,
detergent, and oil.
Unit operations and their contributions to pollution are summarized
in Table 21.
TABLE 21. CONTRIBUTION OF SHELL EGG INDUSTRY UNIT
OPERATIONS TO POLLUTION
Waste product
Unit operation Liquid Solid
Receiving cooler
Machine loading X X
Washing X
Oiling
Candling X
Grading X
Packing (one dozen cartons)
Packing (shipping cases) X X
Out-going cooler
Source: SRI
Utilities needed by shell egg processors are electricity, water
and steam, and refrigeration. Sources of wastewater prior to the
grading of the eggs are:
(1) Cleaning of the egg handling equipment
(2) Cleaning of floors
(3) Overflow and dumping of the egg washwater.
83
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Eggs are sometimes broken during unloading, washing, and candling.
Unloading and candling equipment is normally equipped to catch these
broken eggs, which then may be sold as inedibles. However, some eggs
fall to the floor where they must be scraped or mopped up or hosed into
a floor drain. Eggs broken during washing go into the washwater, and
subsequently into the sewer. Egg washing equipment is normally of the
recirculating type. The same washwater is used over and over with a
small quantity of constant over-flow and make-up. This make-up comes
from the water used to rinse the detergent from the washed eggs. Waste-
water generated during grading and packing comes from cleaning up
broken eggs and equipment cleaning. About 1 percent of the eggs crack
and release organic material to the washwater. Some eggs fall to the
floor where they must be scraped or mopped up or washed into a floor
drain. Wastewater is also generated from the cleaning of the equipment.
Solid waste at shell egg plants is primarily inedible eggs. Eggs
classed as inedibles (e.g., those with blood spots, cracks, leaks, and
stains) are processed separately. Eggs that break on the floor or in
grading machinery are normally recovered and also classed as inedibles.
Inedible eggs are normally put in covered plastic buckets, dyed with a
food color to identify them as inedible eggs, and sold to processors.
Wastewater discharged from one of the largest egg producers in the
nation (Norco Ranch Inc., Riverside, California) amounts to 30,000 gallons
per day (113,400 liters). Of this discharge, 2,000 gallons (7,760 liters)
is highly saline waste and is treated separately from the rest; it is
disposed within an inpermeable evaporator bed to prevent it from coming
into contact with underlying groundwater.
The remaining waste is discharged to the city sewage system. This
wash water, if sprayed onto fields, can be a source of obnoxious odor.
The wastewater released from this ranch contained 8,200 mg/liter total
dissolved solids, and the biochemical oxygen demand (BOD) ranged from
2,850 to 4,000 ppm.
-------
SECTION 16
FRESH FISH
GENERAL INDUSTRY CHARACTERISTICS
The major types of fin fish and shellfish include:
(1) Groundfish (haddock, cod, whiting, flounders, and ocean
perch), lobster, clams, scallops, shrimp, and sardines
from New England.
(2) Menhaden, oysters, clams, scallops, striped bass, and blue
crab from the Middle and South Atlantic.
(3) Shrimp, oysters, red snapper, clams, and mullet from along
the Gulf Coast.
(4) Lake herring, chubs, carp, buffalofish, catfish, yellow
perch, and yellow pike from the Mississippi Valley and the
Great Lakes region.
(5) Tuna, halibut, salmon, groundfish, king and dungeness crab,
scallops, shrimp, and oysters from the Pacific Coast and
Alaska.
The number of fishermen and boats has increased from 11,082 and
6,677, respectively, in 1950, to 32,111 and 21,204 in 1969, an approx-
imate threefold increase in each case during this period. During this
same period U.S. landings have decreased from 323.4 million pounds to
267.8 million pounds, a 17.2 percent decline, whereas value of landings,
including inflation, has nearly doubled from $37.4 million to
$62.9 million.
The present study deals with the presentation and processing of
fresh salmon, halibut, and oysters. It provides information on the care
of fresh fish aboard the vessel and ashore.
HALIBUT
Pacific halibut (Hippoglossus Stenolepsis) is a large fish ranging
to over 80 pounds (36.2 kg), and it is found in the cold bottom waters
of the North Pacific. In accordance with regulations of the International
Pacific Halibut Commission, halibut are caught only on baited long lines
laid along the ocean bottom and they cannot be taken by means of a trawl.
The halibut, after being caught on a long line, are brought over the
rail of the fishing vessel, taken off the hook, and then placed in the
85
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"checker" on the deck for dressing. The belly wall is slit, the viscera
is removed, the gills are cut away, and the halibut, with the head and
nape intact, are passed into the hold for icing.
Ice is packed in both the belly and gill cavities, after which the
fish is laid on a bed of ice in the bin so that the water from the
melting ice will flow around and away from the fish. It is important
that the fish be laid so that any water in the belly cavity drains away
from the fish and does not form a pool of blood and slime along the
dorsal part of the cavity. Otherwise, halibut become sour smelling.
Ample ice is placed around the halibut; this practice avoids exposure
of the halibut to the air as the ice melts.
SALMON
The salmon industry is synonymous with the Pacific salmon
(oncorhynchus) industry and is concentrated in Alaska, Washington,
Oregon, California, and the Canadian Province of British Columbia.
Pacific salmon includes five species: chinook, coho, chum, pink, and
sockeye. Chinook and coho have traditionally been used in fresh and
frozen forms; however, in recent years the other species have also been
marketed in this form. There are generally four methods of salmon
fishing: purse seine, gill net (anchor and drift), troll, and trap.
Trolling is the most common method of landing salmon and is the only
form of salmon fishing permitted off the Oregon, Washington, and
California coastline. Gill netting is permitted on the Columbia, Puget
Sound, and northward. Purse seine is widespread in Puget Sound and
northward.
The method of the catch determines the initial processing. Normally,
the salmon taken by seines or nets are caught fairly close to the cannery
or cold storage and therefore ordinarily require no refrigeration aboard
the vessel. The use of refrigerated seawater has been tried success-
fully for holding cannery salmon, where more than a day's delay is
involved in delivery of the vessels catch to the cannery.
Seining is used extensively in both Puget Sound and Southeastern
Alaska, although Alaskan regulations limit the size of the purse seine
vessel to 50 feet. With both gill netting and purse seining, salmon
are turned over "in the round"; that is, the cleaning is done at
processing facilities onshore.
Trolling is largely a small boat operation with the exception of a
few tuna vessels that participate in salmon fishing in their own off-
season. Trollers commonly fish for a week to 10 days for their king
and silver salmon catch, and handling and icing is an important part of
their job. As the salmon are taken from the water, they are stunned by
a sharp blow on the head and are lifted into the boat with a gaff hook.
The salmon, soon after being caught, are bled and gutted, and the gills
are removed, leaving the nape uncut just below the pectoral fins. This
procedure keeps the belly walls closed during handling and icing, and
86
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minimizes unnecessary exposure to air. A blunt implement is used to
remove the kidney or blood clot, which lies below the backbone in the
belly cavity. Excess blood is wiped away, and the salmon are iced
similarly to halibut, using ice in the belly and gill cavities with
ample ice outside and placing the salmon to allow free drainage of
water, blood, and slime away from the fish.
Gill netting, restricted in Oregon and Washington to a few areas
with protected waters, the Columbia and Puget Sound, has encouraged the
use of small boats. The erratic nature of the seasons, and the con-
servation policies of Fish Commissions have also encouraged large
numbers of fishermen to stay in close proximity to the permitted fishing
areas.
It is important that exposure of the salmon to air be prevented by
protecting them with melting ice; otherwise, yellowing of the cut belly
flesh and flesh around the nape will occur. Larger king salmon (from
15 to 40 pounds or 6.8 to 9 kg) must be handled with special care to
avoid breaking the flesh along the backbone and to keep the skin and
scales intact. This careful handling is important if the salmon are
to meet the grade standards of the high-priced mild cure salmon destined
for later smoking.
A generalized marketing flow diagram for fresh salmon is given in
Figure 9.
Fisherman
Receiving Station
Transportation
Processor—
Transportation
Cold
Storage
Wholesaler
Transportation
Cold Storage- Retail Chain Retailer
-Chain Store
Consumer —
Figure 9. Marketing flow diagram for fresh salmon.
87
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A generalized marketing flow diagram for frozen salmon is given in
Figure 10.
Fisherman
Transportation
Cold Storage
^Receiving Station''
Transportation
'Processor
Transportation
—Cold Storage-
Transportation
Whole
saler-
Cold Storage
etail Chain-
Chain Store
I
Frozen by Fisherman
-Custom House
Broker
Buyer
-Independent Retailer-
-Institution ___^^__
Consumer-
Figure 10. Marketing flow diagram for frozen salmon.
UNIT PROCESSING OPERATIONS
Quality Maintenance
After being brought to the vessel, fish must be promptly and
properly cared for to assure maintenance of maximum quality.
Quality loss in fish is attributable to one or all of three principal
causes:
(1) Enzymatic or autolitic action
(2) Oxidative action
(3) Bacterial action.
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Reduction of storage temperature retards both bacterial or enzymatic
activity. Low temperatures are particularly effective in delaying
growth of the psychrophilic bacteria, which are primarily responsible
for the spoilage of nonfatty fish. It has been reported that the shelf
life of species such as haddock and cod is doubled for each 7 to 10°F
3-5°C) lowering of storage temperature within the range of 60 to 30°F
(16 to 1°C).
Ice, to be effective, must be clean when used aboard the vessel.
Bacteriological tests on ice in the hold of a fishing vessel showed
bacterial counts as high as 5 billion bacteria per gram of ice. These
results indicate that chlorinated or potable water should be used in
making the ice at the ice plant, ice should be stored under sanitary
conditions, and unused ice should be discarded from the vessel at the
end of each trip.
Both flake ice and crushed block ice are used aboard fishing
vessels, although flake ice is preferable because: (1) it is less
expensive to produce, (2) it is easier to handle because it has less
tendency to fuse, (3) the smaller, more nearly uniform size of the ice
particles facilitiates mixing of ice and fish, and (4) there are fewer
large pieces to cause bruising damage to the fish. New England trawlers
used only crushed ice until 1967 when some vessels started using flake
ice.
The amount of ice used aboard vessels varies with the particular
fishery and vessel; however, it is essential to provide sufficient ice
around the fish to obtain a proper cooling rate. A common ratio of ice
to fish used in bulk icing on New England trawlers is 1 part ice to
3 parts fish. Recent trails made on English trawlers in boxing fish at
sea with 1 part ice to 2 parts fish demonstrated improved quality in the
landed fish. Mechanical refrigeration is used on some vessels to retard
melting of the ice while en route to the fishing grounds; however, the
hold temperature must be controlled after fish are taken to allow
melting of the ice for effective cooling of the fish.
Recent findings by Portuguese, English, American, and Canadian
workers indicate that a method of superchilling fish by use of ice and
mechanical refrigeration can be used to extend the shelf life of fresh
fish on the vessel. The fish are chilled to temperatures between 30 and
25°F. The upper temperature is the point at which fish such as cod and
haddock begin to freeze; the lower temperature is the point at which
the activity of spoilage bacteria is virtually stopped. In trials with
cod and haddock, the shelf life of fish held at 30 to 28°F (-1 to -2°C)
was from 22 to 29 days, compared to a normal shelf life of 13 days for
controls in melting ice. In commercial systems used on Portuguese
vessels, the fish is bulk-stowed in ice for cooling to 32 F (0 C), and
is further cooled to as low as 25°F (-4°C) by refrigerated plates and
pipe coils that contain cold circulating brine and are installed in the
hold. Another method being studied is to ice the fish in boxes that
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are spaced apart and further cooled by circulation of cold air.
Currently, it appears that cooling to the lower temperature (25°F or
-4°C) with the resulting partial freezing is satisfactory only for
some species used in a fresh market. Fish to be filleted, such as cod
and haddock, should be held at 28°F (-2°C) or above to minimize
undesirable texture changes caused by partial freezing.
Salt-water Icing
The importance of maintaining iced fish storage temperatures close
to the freezing point of fish has been stressed by several workers.
One method of obtaining lower ice temperatures is to depress the freezing
point by adding salt to the water from which the ice is made. Adequate
amounts of ice made from a 3 percent solution of sodium chloride brine
will maintain a storage environment of about 30°F (-1°C) for the fish.
Tests conducted on the storage of haddock in salt-water ice showed that
those fish were cooled faster and to a lower temperature than were fish
iced in plain ice. However, the salt-water ice melted faster than the
plain ice because of the lower latent heat and greater temperature
differential of the salt-water ice. Therefore, once the salt-water ice
melted, the fish stored in this ice rose to a higher temperature than
those stored in plain ice. Since it is not always practicable to renew
ice on fish at sea, sufficient quantities of salt-water ice must be used
initially to make up for the faster melting rate.
In making ice from water containing a preservative, rapid freezing
or the use of a stabilizing dispersant, or both, is essential to prevent
migration of the additive to the center of the ice block. This problem
is not encountered in flake ice because flake ice machines are designed
to freeze water rapidly into thin layers of ice, thus fixing additives
within the ice flakes.
Use of Preservatives for Treatment of Chilled Fish
In the United States the use of antibiotics in ice or in dips for
treatment of whole or gutted fish, shucked scallops, and unpeeled shrimp
was revoked, in effect, during 1967 when the Food and Drug Administra-
tion deleted the tolerances for antibiotic substances in these and
other foods from the pesticides regulations. Several preservatives
are acceptable and are used to some degree for extending the shelf life
of fresh fish and shellfish. These include chlorine compounds,
benzoates, and chemicals that inhibit the growth of spoilage bacteria
on fish. Such preservatives are of most value when used on high quality
fish along with good handling, sanitation, and storing procedures.
The use of refrigerated sea water (RSW) is limited in the United
States and Canada for preserving fish to be canned or to be used for
industrial products.
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Boxing at Sea
The use of containers instead of bulk storage aboard fishing
vessels offers many advantages. This procedure is known as boxing at
sea and it is successfully used by European fisheries. However, it is
not generally practiced in the United States because it requires
additional labor for handling boxes on the vessel.
Shore Plant Procedure and Marketing
Proper use of ice and adherence to good sanitary practices are
necessary to assure maintenance of iced fish freshness during unloading
from the vessel, at the shore plant, during processing, and throughout
the distribution chain. Fish landed in good quality will spoil rapidly
if these practices are not carried out.
Fish unloaded from the vessel are usually graded by the buyer for
species, size, and minimum quality specification. A price is based
in part on the quality in relation to market requirements. Fish may
also be inspected by local and federal regulatory agencies for whole-
someness and sanitary condition. Organoleptic criteria are most
important for evaluating quality; however, there is a growing acceptance,
particularly in Canada and some European countries, of objective
chemical and physical tests as indexes of quality loss or spoilage.
After the fish are brought into the plant, they are beheaded, if
this has not already been done at sea, and the body cavity is flushed
to remove ice. The fish are graded by size and then processed whole
or fletched. Wooden boxes are frequently used for transporting fish, but
they are not recommended for reusable applications because they are a
source of microbiological contamination. Ice should be applied
generously to each box of fish, even if the period prior to holding
is only a few hours.
Large boxes of resin-coated plywood, reinforced fiberglass, or
plastic, which hold up to 1,000 pounds (454 kg) of fish and ice, are
used by some plants in preference to icing fish overnight on the floor.
These tote boxes are moved and stacked by use of a fork lift, can be
used for trucking fish to other plants, and make better use of plant
floor space.
Fresh fish are marketed in many different forms: fillets, whole
fish, dressed-head on, dressed-headed (head removed), or in some
instances as steaks. The method of preparing fish for marketing
depends largely on the species of fish and on consumer preference.
Packaging
At the point of processing, most fresh fish is packaged in
institutional containers of 5- to 35-pound (2.25 to 16 kg) capacity.
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Steel cans, aluminum trays, plastic-coated solid fiber boxes, wax-
impregnated corrugated fiberboard boxes, foamed polystyrene boxes, and
polyethylene bags are used.
Fresh fish is often packaged while it still contains process heat
from wash water. When this is done, it is advantageous to use a
packaging material that is a good heat conductor. The fresh fish
industry makes little use of controlled prechilling equipment in
conjunction with packaging systems, and, as a result, product tempera-
tures may never reach the optimum level subsequent to packaging.
Traditionally, institutional fresh fish travels packed in wet ice; in
this case, it may cool to the proper level in transit even if process
heat is initially present. However, there is a trend toward the use of
leaktight shipping containers for fresh fish, because modern transporta-
tion equipment is not designed to handle wet shipments. This require-
ment virtually precludes the use of wet ice in shipping containers;
shippers who make use of leaktight shipping containers will have to
upgrade their product temperature control systems to ensure that the
fish reaches ice temperature prior to packaging. Rapid prechilling systems
that result in crust freezing can be applied to some fresh seafood
products, but this practice must be used with discretion since it some-
times produces deleterious effects on quality.
Some general requirements for institutional containers for products
such as fillets, steaks, and shucked shellfish are: (1) the container
should have sufficient rigidity to prevent pressure from being exerted
on the product, even when containers are stacked or heavily covered with
ice; and (2) the container should prevent ice melt-water from contacting
the product. Some containers are provided with drains to permit the
drip associated with the fish itself to run off. Others are sealed and
may be gastight. Increased shelf life has been reported in conjunction
with the use of gastight containers. One problem associated with sealed
containers, however, is the accumulation of a strong odor that is
emitted when the package is first opened. Although this odor may be
somewhat foul, it soon dissipates and has no adverse effect upon quality.
Dressed or whole fish may be placed in direct contact with ice in a
gastight shipping container.
Shipping containers for fresh fish, if they are of the draining
type, may be of nailed wood, wirebound wood, wax-impregnated corrugated
fiberboard, or foamed polystyrene. They are usually of 100- to
200-pound (454-908 kg) capacity. Reusable shipping containers are seldom
used.
Leaktight shipping containers are used with nonrefrigerated
transportation systems such as air freight, and, consequently, they
require insulation. Foamed polystyrene is particularly suited for this
application. For typical air freight shipments, the most economical
thickness of insulation is between 1 and 2 inches. To maintain product
temperature in transit, shippers use either dry ice, packaged wet ice,
packaged gel refrigerant, or wet ice with absorbent padding in the
bottom of the container.
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Foamed polystyrene containers may be of molded construction, or
they may be of the composite type in which foam inserts and a plastic
liner are used in conjunction with a corrugated fiberboard box.
At the retail level, fresh fish may be handled by either of two
methods. Stores with service counters display their fish in unpackaged
form. Many markets do not have service counters, however, so their fish
must be packaged for the consumer prior to displaying for sale. Both
types of outlets normally receive the product in institutional
containers. If the fish is prepackaged at the market, high labor and
packaging costs may be incurred; in addition, the temperature of the
product is likely to rise. Often, relatively warm fish is placed in a
foam tray, wrapped, and displayed in a meat case, the temperature of
which may be 40°F (5°C) or more. This drastically reduces the shelf
life of the fish. Centralized prepackaging at the point of initial
processing appears to have many important advantages over the present
system.
Storage
The maximum storage life of fish varies from species to species.
In general, the storage life of East and West Coast fish properly iced
and stored in refrigerated rooms (35°F or 2°C) is about 10 to 15 days,
with 15 days as the maximum. This is dependent on the condition of the
fish when unloaded from the boat. Generally, fresh-water fish properly
iced in boxes and stored in refrigerated rooms may be held for only
7 days. Both figures are from the time the fish is landed and
processed to the time of consumption.
Cold storage facilities for fresh fish should be maintained at
about 35°F (2°C) and over 90 percent humidity. Air velocity should be
limited to control ice loss. Temperatures less than 32°F (0°C) retard
ice melting and can result in excessive fish temperatures. This is
particularly important when storing round fish such as herring, which
generate heat from autolytic processes.
Floors should have adequate drainage with ample slope toward
drains. All the inside surfaces of the cold storage room should be of
a construction that is easy to clean and must have the capacity to
withstand the corrosive effects of frequent washings with antimicrobial
compounds.
OYSTERS
General Industry Characteristics
The oyster industry can be arbitrarily broken down into two areas—
the East and Gulf Coast, and the West Coast.
The East/Gulf Coast harvests the American or Eastern oyster; the
leading producers are located in Maryland, Louisana, Virginia, and
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Florida. James River in Virginia is the largest seed oyster producing
area in the world and supplies over 70 percent of the oysters planted
in Virginia. Connecticut estuaries are important seed producers that
supply most of the seed used by Long Island oyster farms. Harvesting
techniques vary with local regulations and are frequently limited to
inefficient, labor intensive methods on public grounds. Private
operators, on the other hand, can often use efficient escalator and
hydraulic dredge boats. Additionally, private oyster farmers can
harvest beds throughout the year, whereas public areas are frequently
closed A to 5 months of the year depending on local regulations.
West Coast oyster production is centered on the large Pacific
oyster, with limited production of the small Western native oyster in
the Puget Sound area. West Coast production is almost entirely by
aquaculture on privately leased bottoms, with Washington the major
producer. Most seed oysters are still imported from Japan, a practice
started in the 1920s; however, there is increasing reliance on
hatching seed, and some limited natural set occurs. Harvesting
techniques vary and depend largely on the bottom and tidal amplitude.
Aquaculture is important to the national production of oysters.
In 1974, aquacultural activities accounted for 40 percent of the U.S.
oyster harvest.
The oyster industry is one of the top five fisheries providing
employment in the harvesting, processing, and distribution of seafood.
In 1973 there were approximately 11,748 oyster harvesters (including
part-time harvesters). The number of harvesters has been decreasing
from an average of 14,000 in the 1950s and 13,700 in the 1960s.
Domestic landings of oysters have declined from 90 million pounds
(meat weight) in 1929 to an average of 53.9 million pounds in the
1971-75 period. On the other hand, the value of production has been
increasing. The harvest value in 1967 was $32.2 million compared to
$45 million in 1975. Corrected for inflation, the on-vessel prices
actually declined in the period 1968-73 and then increased by 14 per-
cent in 1975. This trend can be compared with prices paid to fisherman
for all edible fish, which has more than doubled since 1967.
Oysters are marketed mainly in fresh product form. The sale of
oysters in the shell for raw consumption has significant regional
importance. Almost all the oysters produced by oyster farms in Long
Island are sold for the raw bar trade, and in Louisiana, private beds
are harvested year around to meet the market demands in New Orleans.
On the other hand, native Western and Pacific coast oysters are not
normally eaten raw.
Unit Processing Operations
Oysters are delivered alive in the shell to the shore plant. They
are unloaded from the boats by means of a bucket or hoist or by conveyors.
-------
The processing of oysters consists of two basic operations—shucking
and packing. Shucking of the oyster is accomplished using either manual
or mechanical methods. Manual operations are more prevalent.
In mechanical operations the oysters, after arriving at the plant
in wire cages, are conveyed into the plant to two sequential drum
washers. The first washer cleans the oyster shells, and removes broken
shell, seaweed, and other matter. Dead oysters are discarded. The
second washer has a different pitch and serves to jar the valves far
enough apart to allow steam to enter during the cooling. Loose empty
shells are manually removed before the oysters are collected in retort
baskets. The oysters are steamed in retorts under pressure and the
resulting oyster juice or broth is piped to a holding tank and later
condensed. After cooling the meat is separated from the shell manually
or by brine flotation, or by a mechanized method using a specially
designed drum washer. Both the meat and the shell are collected in a
brine flotation tank when the buoyancy of the meats allow the saturated
salt solution to float them to a blow tank that agitates and adds
water to the product. The shells sink to the bottom of the brine tank,
where a belt collects them and deposits them outside the plant. The
meats go through a final drum washer before being manually inspected.
The oyster meat then is fresh packed in large cans together with the
condensed broth, chilled, and shipped.
In hand-shucked oyster processing, the oysters arrive at the plant
by boat, barge, or truck and conveyed into the plant on a belt or in
buckets. The shells are washed to remove most of the mud, and to
facilitate shucking. Shuckers open the shells manually by forcing the
valves apart and cutting the adduction muscle. The meat is put into
buckets, washed on a skimmer table, and placed in the blow water. The
blow washer typically holds about 80 gallons (300 liters) of water.
For the first 5 to 15 minutes, air is bubbled through the washer; for
the following 20 to 50 minutes, overflow water is added to the tanks.
The oysters are dewatered on a skimmer table and then packed in cans.
Unit operations and their contribution to pollution are summarized
in Table 22. Utilities needed by fresh fish processors are electricity,
gas, steam, water, and refrigeration.
Devisceration of fish is generally accomplished at sea. After
being washed, the fish is maintained in ice storage. Onshore, the fresh
fish is packaged in institutional containers and delivered to the retail
outlet in ice. The fresh fish industry comprises a large number of
plants, with wastewater flows and loads of great variability. The
waste loads from the halibut processing operation are relatively low.
Processes having an average of 4.3 kilograms/hour production the _
flow rate was observed as 110 gallon/minute (6.94 liters/second) with
BOD5 content of 396 mg/liter, and 326 mg/liter TSS.
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TABLE 22. CONTRIBUTION OF OYSTER INDUSTRY UNIT
OPERATIONS TO POLLUTION
Unit operations
Water
Solids
Halibut, salmon
Devisceration
Icing
Preservative treatment
Unloading from vessel
Grading
Inspection
Boxing (ice)
Preparation for market
(filleting, descaling)
Packaging for shipment
Prechilling
Shipping
Storage
Packaging for retail
Oysters
Delivery
Holding bins
Drum wash
Impact shock
Empty shell removal
Retort
Shucking
Brine flotation/grading
Blow washing
Drum washing
Packing
Chilling
Shipping
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Source: SRI
Waste loads from steamed and canned oyster processes are reported
to be higher than those from the hand-shucked operations. The oyster
processes mean production of 0.712 ton/hour produced
13.3 liters/second (211 gallon/minute) waste flow containing 624 mg/
liter BOD5 and 1,580 mg/liter TSS (total suspended solids).
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REFERENCES AND BIBLIOGRAPHY
Fresh Fruits and Vegetables
Anderson, R. E., 1965. "Controlled Atmosphere Storage - A Review of
Literature on Harvesting, Handling, Storage and Transportation of
Apples," USDA ARS 51-4, 85-102.
Anon., 1965. "A Review of Literature on Harvesting, Handling, Storage,
and Transportation of Apples," USDA ARS 51-4.
ASHRAE, 1971. Guide and Data Book Applications (Am. Soc. of Heating,
Refrigerating, and Air-Conditioning Engineers, Inc., New York, NY).
Barger, W. R. , 1962. "Vacuum-Cooling Lettuce in Commercial Plants,"
USDA, Market Quality Research Division, AMS-469.
Blanpied, G. D. , E. D. Markwardt, and C. D. Ludington, 1962.
"Harvesting, Handling and Packing Apples," N.Y. College of Agric. ,
Cornell, Extension Bulletin 750.
Childers, N. F., 1973. Modern Fruit Science, 5th Edition (Horticultural
Publications, Rutgers University, New Brunswick, NJ).
Dewey, D. H. , et al. , 1960. "Development of Hydrohandling System for
Sorting and Sizing Apples for Storage in Pallet Boxes," USDA Markets,
Research Report 743.
Grierson, W., A. H. Bennett, and K. K. Bowman, 1970. "Forced-Air
Precooling of Citrus Fruit on a Moving Conveyor," USDA ARS 52-40.
Jones, H. A., and L. K. Mann, 1963. Onions and their Allies (Inter-
science Publishers Inc., NY).
Jones, J. L. , et al. , 1978. Overview of the Environmental Control
Measures and Problems in the Food Processing Industries. EPA Report
in print, Appendix A.
Lutz, J. M. , and R. E.-Hardenburg, 1968. The Commercial Storage of
Fruits, Vegetables, and Florist and Nursery Stocks. USDA Agriculture
Handbook No. 66.
Mitchell,1 F. G. , R. Guillou, and R. A. Parsons, 1972. "Commercial
Cooling of Fruits and Vegetables," Calif. Agric. Expt. Sta., Manual 43.
97
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Nagy, S., P. E. Shaw, and M. K. Veldhuis, 1977. Citrus Science and
Technology, Vol. 2 (AVI Publishing Co., Westport, CT).
Ryals, A. L., and W. J. Lipton, 1972. Handling, Transportation and
Storage of Fruits and Vegetables, Vol. 1 (AVI Publishing Co. Inc.,
Westport, CT).
Ryals, A. L., and W. T. Pentzer, 1974. Handling Transportation and
Storage of Fruits and Vegetables. Vol. 2 (AVI Publishing Co., Westport,
CT).
Stout, B. A., et al., 1960. "A Prototype .Hydrohandling System for
Sorting and Sizing Apples Before Storage," USDA ARS 52-14.
Ware, G. W., and J. P. McCollum, 1968. Vegetable Crops (The Interstate
Printers & Publishers, Inc., Danville, IL).
Woodroof, J. G., ed., 1967. Tree Nuts. Production, Processing,
Products, Vols. I, II (AVI Publishing Co., Westport, CT).
98
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REFERENCES
Fresh Fish
Anon., 1977. A Comprehensive Review of the Commercial Oyster Industries
in the United States, U.S. Department of Commerce, National Marine
Fisheries Services, Washington, D.C.
ASHRAE, 1971. Guide and Data Book Applications, Chapter 25, Fishery
Products (Am. Soc. Heating, Refrigerating and Air-Conditioning Engineers
Inc., New York, NY), pp. 323-36.
Borgstrom, G. , 1965. Fish as Food, Vol. IV (Academic Press, New York,
NY).
Burgess, G.H.O., et al., 1967. Fish Handling and Processing (Chemical
Publishing Company Inc., NY).
Butler, C. , et al, , 1963. "Handling Fresh Fish," U.S. Department of
the Interior, Fishery Leaflet, 428.
Train, R. E. , et al. , 1975. "Development Document for Effluent
Limitations Guidelines and New Sources Performance Standards for the
Fish Meal, Salmon, Bottom Fish, Clam, Oyster, Sardine, Scallop, Herring,
and Abalone Segment of the Canned and Preserved Fish and Seafood
Processing Industry Point Source Category," EPA 440/l-75/041a Group I,
Phase II.
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REFERENCES
Shell Eggs
Anon., 1977. List of Chemical Compounds Authorized for Use Under USDA
Meat Poultry, Rabbit and Egg Products Inspection Programs, USDA MPI-8,
January 1, 1977; Supplement July 1, 1977.
ASHRAE, 1971. Guide and Data Book Application (Am. Soc. Heating,
Refrigerating and Air-Conditioning Engineers Inc., New York, NY).
Stadelman, W. J., and 0. J. Cotterill, 1977. Egg Science and
Technology, Second Edition (AVI Publishing Co., Westport, CO).
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/2-78-216
2.
3. RECIPIENT'S ACCESSION-NO.
TITLE ANDSUBTITLE
OVERVIEW OF THE FRESH PACK FOOD INDUSTRIES
5. REPORT DATE
December 1978 issuing date
6. PERFORMING ORGANIZATION CODE
. AUTHOR(S)
L. P. Somogyi and P. E. Kyle
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
SRl International
3333 Ravenswood Avenue
Menlo Park, CA 9^025
10. PROGRAM ELEMENT NO.
1BB610
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Lab.
Office of Research & Development
U. S. Environmental Protection Agency
Cincinnati, Ohio i*5268
- Cinn, OIT
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Pollution sources generated during the market preparation of fresh fruits, vege-
tables, fish and shell eggs were assessed. From the over one hundred different
fruits and vegetables that are grown commercially in the United States, ten of the
largest volume crops were selected for this study representing over 70 percent
of the total volume. In addition, because of the specificity of their handling
requirements, two nut crops, two species of fresh fish and fresh eggs were also
included in this study. The method of approach used in conducting the study was
to prepare descriptions on unit operations for each crop and to identify the
extent of water usage, sources of effluent and emission from each step from har-
vest to shipment to market.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Food, Waste Water, Eggs, Fishes,
Chemical Engineering, Fruits, .Vegetables
Solid Waste, Fresh
Pack
68D
13. DISTRIBUTION STATEMENT
Release to Public
____^—————•—
EPA Form 2220-1 (9-73)
19. SECURITY CLASS (
Unclassified
111
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
101
J U.S. GOVERNMENT PRINTING OFFICE; 1979 -657-060 /1541
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