EPA 660/2-74-006
APRIL 1974
Environmental Protection Technology Series
Wastewater Abatement in Canning
Vegetables by IQB Blanching
Office of Research and Development
U.S. Environmental Protection Agency
Washington, D.C. 20460
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL
PROTECTION TECHNOLOGY series. This series
describes research performed to develop and
demonstrate instrumentation, equipment and
methodology to repair or prevent environmental
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.
EPA REVIEW NOTICE
This report has been reviewed by the Office of Research and
Development, EPA, and approved for publication. Approval
does not signify that the contents ncesssarily reflect the
views and policies of the Environmental Protection Agency,
nor does mention of trade names or commercial products consti-
tute endorsement or recommendation for use.
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EPA-660/2-74-006
April 1974
WASTEWATER ABATEMENT IN CANNING VEGETABLES
BY IQB BLANCHING
By
Daryl B. Lund
University of Wisconsin
Madison, Wisconsin
Grant No. S-801484
Program Element 1BB037
Project Officer
Mr. Harold Thompson
Pacific Northwest Environmental Research Laboratory
Corvallis, Oregon 97330
Prepared for
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
For sale by the Superintendent or Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.25
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ABSTRACT
This report presents the results of a study on the efficacy of a new blanching
system, Individual Quick Blanch (IQB), as applied to vegetables prior to
canning. Peas, corn, lima beans, green beans, potatoes, carrots and beets
were adequately blanched by IQB. Compared to deep bed steam blanching or pipe
blanching, IQB generally resulted in a significant reduction in effluent.
Slight drying of the vegetables before IQB reduced effluent even more; how-
ever, product quality was adversely affected in most cases. It was demon-
strated that the IQB process can significantly reduce effluent volume and BOD
generation in the blanching operation while adequately fulfilling the objec-
tives of blanching. Commercial application of IQB appears economically
favorable.
This report was submitted in fulfillment of Project Number S-801484, by
Daryl Lund, University of Wisconsin, under the partial sponsorship of the
Environmental Protection Agency. Work was completed as of August 1973.
ii
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CONTENTS
Page
Abstract ii
List of Tables iv
Acknowledgments vi
Sections
I Conclusions 1
II Recommendations 2
III Introduction 3
IV Objectives 7
V Materials and Methods 8
VI Results and Discussion 18
VII Units for Interconversion of Data 56
VIII References 58
IX List of Publications 60
X AppendixRaw Data 61
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TABLES
No. Page
1 Product Forms and Processing Dates 9
2 Blanching Methods 10
3 Blanching Times and Temperatures 15
4 Product Evaluation Tests
5 Hourly Make-up Water Flow Rates and Total Solids 20
Content of Pipe Blancher Water for Peas, Corn, Lima
Beans and Green Beans
6 Summary of Pea Blanching Data 23
7 Summary of Objective Evaluation of Peas 27
8 Summary of Subjective Evaluation of Peas 29
9 Summary of Corn Blanching Data 30
10 Summary of Objective Evaluation of Corn 31
11 Summary of Subjective Evaluation of Corn 33
12 Summary of Lima Bean Blanching Data 34
13 Summary of Objective Evaluation of Lima Beans 36
14 Summary of Subjective Evaluation of Lima Beans 37
15 Summary of Green Bean Blanching Data 38
16 Summary of Objective Evaluation of Green Beans 41
17 Summary of Subjective Evaluation of Green Beans 42
18 Summary of Potato Blanching Data 42
19 Summary of Objective Evaluation of Potatoes 44
20 Summary of Subjective Evaluation of Potatoes 45
21 Summary of Beet Blanching Data 46
iv
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TABLES
No. Page
22 Summary of Objective Evaluation of Beets 49
23 Summary of Subjective Evaluation of Beets 50
24 Summary of Carrot Blanching Data 51
25 Summary of Objective Evaluation of Carrots 52
26 Summary of Subjective Evaluation of Carrots 52
27 Estimated IQB Production Units 56
28 Factors for Interconversion of Data 57
29 Canning Yield Factors 58
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ACKNOWLEDGMENTS
The cooperation and support of this project by the Oconomowoc Canning Company,
Oconomowoc, Wisconsin, is acknowledged with sincere thanks. Personnel at the
Sun Prairie and Waunakee Plants provided valuable assistance.
Partial financial support was provided by the Wisconsin Canners and Freezers
Association and their contribution is gratefully acknowledged.
The IQB blanching unit was supplied by the Western Regional Research Labora-
tory, USDA, Berkeley, California. Obviously, without their support this
project would not have been possible.
Thanks is also extended to the Hughes Company, Columbus, Wisconsin, for
supplying some of the equipment required in this project.
A special thanks is extended to the Water Quality Laboratory, Wisconsin State
Department of Natural Resources, Madison. This laboratory performed most of
the water quality tests and thus provided the bulk of the raw data in this
report.
Finally, acknowledgment is extended to personnel in the Department of Food
Science who contributed to the successful completion of this project. Special
thanks goes to the personnel of the Sensory Evaluation Laboratory and the
taste panel members.
vi
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SECTION I
CONCLUSIONS
Conventional blanching operations result in the generation of high volume,
high strength waste streams. The efficacy of a new blanching system, Indi-
vidual Quick Blanching, was assessed with the objective of significantly re-
ducing blanching effluent while maintaining product quality. IQB was applied
to peas, corn, lima beans, green beans, potatoes, beets and carrots prior to
canning.
IQB was found suitable for blanching vegetables prior to canning. Effluent
generation was significantly reduced for peas, corn, lima beans and green
beans compared to pipe blanching and deep bed steam blanching. Product quality
tests indicated that IQB blanched, canned products were as good as pipe
blanched, canned products. For potatoes, beets and carrots, IQB could be
effectively used to inactivate peroxidase while minimizing inequity of heat
treatment received by the surface and center of the product.
Slight drying of the product prior to IQB further reduced blancher effluents.
However, generally canned product quality was adversely affected by this pre-
treatment.
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SECTION II
RECOMMENDATIONS
This study was limited to a pilot plant evaluation of the individual quick
blanching (IQB) system. It successfully demonstrated the potential of reduc-
ing canning plant effluent through the use of IQB. Peas, corn, lima beans,
green beans, potatoes, carrots and beets were adequately blanched by IQB and
product quality was in most cases as good as the conventionally blanched-
canned product.
The next step for the development of IQB as a commercially viable blanching
system would be the design and installation of a full size production unit.
For that purpose, information contained in this report and in other published
papers on IQB could be utilized for providing design parameters (loading rates
and residence times).
If a private company or food equipment manufacturing company does not under-
take the development of a commercial IQB unit, it is recommended that EPA seek
a participant for a demonstration grant. Preferably a company with both
freezing and canning facilities would undertake the project since the full
potential of IQB as a blanching method could then be evaluated.
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SECTION III
INTRODUCTION
GENERAL
Upgrading and maintenance of the environment is a major priority
of government and private sector action. For the solution to the
environmental problems, research and development activities are
directed in three major areas: (1) identification of major pollu-
tion input from industrial and other sources, (2) development of
alternative processes which eliminate or reduce effluent streams,
and (3) development of effective, economically feasible utiliza-
tion or treatment of waste material. In connection with these
three activities, it was recognized that the food processing indus-
try needed considerable effort. Although the food industry has
advanced technologically in the conversion of raw agricultural
products to consumer-acceptable products, little attention has been
given to use of water and generation of high strength, large volume
waste streams.
Waste management within food processing has several distinctive
characteristics which do not allow the direct adaptation of prac-
tices used in other industries. First, processing of fresh agri-
cultural plant material into consumer products is generally sea-
sonal in nature resulting in an uneven demand for treatment facili-
ties. This has created difficulties since it requires that the
food plant either have its own treatment facilities which are used
sporadically or that the food plant discharge its waste into
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municipal or other treatment facilities creating unusual peak
demands. In either case, waste treatment problems are somewhat
unique.
Second, the composite waste stream generated in the food processing
plant is usually a high volume, relatively low strength stream.
This results from the fact that water is required in nearly all
unit operations in food processing and usually little effort is
made to segregate streams based on organic strength.
BACKGROUND
Recent research activity designed to aid the food processing in-
dustry has centered on identifying those unit operations where high
strength, high volume waste streams are generated and development
of technology resulting in reduction of waste generation at those
unit operations. Receiving considerable attention has been the food
canning industry. In the conversion of raw agricultural product to
shelf-stable canned products, waste streams of significant volume
and strength are generated per unit of product. Analysis of the
individual unit operations in canning indicates that the unit opera-
tion blanching (sometimes referred to as scalding) is a major source
of effluent . With identification of a major pollutional source,
considerable research effort has been directed toward development
of effective, economically feasible blanching operations.
The blanching operation fulfills several necessary functions includ-
ing removal of tissue gases; inactivation or activation of enzymes,
reduction of microbial load, cleansing of product, wilting of tissue
to facilitate packing, and elevation of product temperature going
into the retort. Currently, the food industry uses both hot water
and steam for blanching. Both methods produce liquid wastes high
in biochemical oxygen demand (BOD) and volume, and both result in
loss of water soluble nutrients. Based on data reported by Weckel
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et al. for two Wisconsin canning plants, a 90% reduction in blancher
effluent would reduce total plant waste flow by 10 to 20% and, more
significantly, reduce total plant BOD by 20 to 50%. The National
2
Canners Association estimated that if a new blanching method which
reduced waste water strength by 5070 were used for the seven vege-
tables processed in the largest tonnage, a total of approximately 32
million kg. (70 million pounds) of BOD and 18 million kg. (40 million
pounds) of suspended solids would be eliminated from treatment plant
loadings.
In the abatement of waste water flow and loss of solids from product
in canning and freezing plants, a study was initiated in 1970 to
design a blanching process which would have a waste water flow of
only 107<> of a commercial hot water blancher. The project was sup-
ported by the University of Wisconsin and the USDA, and was conducted
by M. E. Lazar and D. B. Lund at the Western Marketing and Nutrition
Research Division, USDA. The project resulted in a new concept of
3 4
heating foods and the application to blanching was demonstrated * .
The process, individual quick blanch (IQB), required further evalua-
tion and, therefore, the Western Laboratory conducted a study uti-
lizing IQB prior to freezing while the evaluation of IQB for blanch-
ing prior to canning was conducted in a Wisconsin canning plant.
The IQB process is a two-stage unit operation. In the first stage,
the food piece is exposed to a heat source (condensing steam) for
such duration that the mass-average temperature is in the range re-
quired for blanching (generally greater than 85 C [185 F]). The
piece is then transferred to a second stage where the piece is held
adiabatically until the thermal gradients have equilibrated to the
mass average temperature and the objectives of blanching have been
accomplished. The process results in less waste generation because:
1) steam condensation is limited to that required for heating the
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product into the blanching temperature range, 2) there is minimal
opportunity for tissue damage and subsequent loss of cellular juices,
and 3) there is no overheating of some of the tissue as in deep bed
steam blanching which can result in tissue damage.
Lund reported on the application of IQB to vegetables prior to
canning. In that study, peas, corn, lima beans and green beans were
blanched, canned, stored and objectively and subjectively evaluated.
Evaluation of IQB, IQB with predrying and conventional pipe blanching
showed that up to a 99% reduction in waste water generation could be
achieved with IQB. The study also revealed that although predrying
to greater than a 67» weight reduction would further reduce waste
water generation, product quality was adversely affected.
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SECTION IV
OBJECTIVES
The results in this report are a continuation and extension of the 1971
study. The present study was undertaken for several reasons: 1) to con-
firm the 1971 results with IQB, 2} to compare the IQB process to deep-bed
steam blanching, 3) to apply the IQB process to different varieties of
peas, 4) to extend the IQB process to the blanching of root crops such as
potatoes, carrots and beets, and 5) to evaluate the heat-only stage of
the IQB process as a blanching method. Objective 5) was included in the
study since it had been observed that after blanching, and prior to can
filling, vegetables are often held for one to two minutes during which
thermal equilibration could be accomplished. If the vegetables could be
held in a relatively large mass to reduce thermal losses, blanching could
be accomplished. The vegetables used in this study include peas (smooth
and wrinkled-skin varieties), corn, lima beans, green beans, potatoes,
carrots and beets.
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SECTION V
MATERIALS AND METHODS
PRODUCTS AND PROCESSING TIMETABLE
Products chosen for this study were those grown and/or processed in
large quantity in Wisconsin. The 1971 study was done on Alsweet
peas, Midway corn, Slim Green green beans and lima beans (variety
unknown), and consequently, to verify the 1971 study, these products
were used in this study. Since there was concern regarding the
response of the smooth-skin pea variety to the IQ8 process, Alaskan
peas were also used. Two wrinkled-skin varieties, Alsweet and Per-
fection, were used. In addition to these four vegetables, the root
crops, potatoes, carrots and beets, were also processed.
The effect of harvest date on the characteristics of blancher ef-
fluent was assessed by making blanching runs throughout the process-
ing season. Experiments were conducted on three days for peas and
corn, two days for lima beans and green beans and one day for pota-
toes, carrots and beets. Product forms and processing dates are
given in Table 1.
All products used in this study were obtained from either the Sun
Prairie, Merrill, or Waunakee plants of the Oconomowoc Canning
Company, Oconomowoc, Wisconsin. Peas were taken from the produc-
tion line immediately after inspection and just prior to blanching.
They were transported to the pilot plant at the Department of Food
Science, Babcock Hall, University of Wisconsin-Madison under water
8
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to minimize product deterioration. The blanching run was started
within two hours of leaving the canning plant.
Table 1. PRODUCT FORMS AND PROCESSING DATES
Processing
date
6/22/72
6/26/72
7/26/72
8/16/72
8/31/72
9/11/72
10/ 3/72
10/11/72
10/ 9/72
10/10/72
10/31/72
III 2/72
ll/ 7/72
Product
Peas
Peas
Peas
Corn
Corn
Corn
Lima bean
Lima bean
Green bean
Green bean
Potatoes
Beets
Carrots
Variety
A 1 sweet
Alaskan
Perfection
Midway
Midway
Midway
Thorogreen
Thorogreen
Slim green
Slim green
Superior
Ruby queen
Nantes
Form
4 sieve
3 sieve
3, 4, 5 sieve (mixed)
Whole kernel
Whole kernel
Whole kernel
3 sieve
3 sieve
3.8 cm.
3.8 cm.
0.64 cm. (1/4 in.) slice; medium
0.64 cm. (1/4 in.) slice; medium
0.64 cm. slice; medium
Corn was taken out of the processing line immediately before the
conventional blanching step. The corn had been washed and screened,
It was also transported to the pilot plant under water.
Cut green beans were received from the Merrill, Wisconsin plant and
were transported from the plant to Madison by truck. The green
beans were blanched and further processed immediately after receiv-
ing them.
Lima beans were taken from the processing line immediately after
inspection and were transported to the pilot plant under water.
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Potatoes, carrots and beets were obtained from the Waunakee plant.
All root crop products had been steamed and/or lye-treated, peeled,
graded, and sliced. Medium slice (3.2 - 4.4 cm. diameter) was used
in the blanching studies. Tests indicated that there was enzymic
activity (peroxidase) even though the product had received a thermal
treatment. The product was brought to the laboratory and processed
immediately.
BLANCHING METHODS AND EQUIPMENT
Five blanching methods were investigated in this study and are shown
in Table 2. The first method was IQB (individual quick blanch).
Table 2. BLANCHING METHODS
Method
IQB
IQB with
predrying
IQB heat
only
Deep bed
steam
Pipe
Peas
X
X
X
X
X
Corn
X
X
X
X
X
Lima
beans
X
X
X
X
X
Green
beans
X
X
X
Pota-
toes
X
X
X
Carrots
X
X
Beets
X
X
X
The equipment was the same as that described in an earlier publica-
3
tion and was on loan from the Western Regional Research Laboratory.
In essence the equipment consisted of two
separate belt units, the first of which was approximately 91.4 cm.
(3 ft.) by 21.6 cm. (8.5 in.) and the second of which was approxi-
mately 122 cm. (4 ft.) by 20.3 cm. (8 in.). The first unit was the
heating section and had a feed hopper through which a single layer
of product could be discharged onto the moving belt. The residence
10
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time in this unit could be varied from 20 sec. to 2.5 rain. The
second unit, the hold unit, had adjustable belt speed and tunnel
length. Tunnel length was adjusted by changing the length of the
cover on the unit. In all experimental runs reported here, the
effective belt length was 30.5 cm. (1 ft.). A diagram of the IQB
unit is shown in Figure 1.
Figure 1. IQB BLANCHING UNIT
(
-MONOLAYER
I
)
- x. ^ C
v
LJCATIM/- ccn ir\M C
,V
*\s"**
CUR
Daae>««« d*n
« o a a A aJU0l
^ r
TAIN
J MULTIPLE
^-LAYER
V ~7^
Fast Belt
(Live Steam Heat)
HOLDING COOLING SECTION
SECTION (Optional)
Slow Belt (Chilled Air)
(Insulated, Adiabatic)
The heat unit was heated by live steam which was distributed by two
pipe distributors, one below and one above the belt. The distributor
below the belt directed the steam parallel to the belt so product
would not be blown off the belt, and the distributor above the belt
was directed toward the cover on the unit. The hold section was
heated indirectly by steam in two copper coils, one on each wall
of the unit. The steam condensate and excess steam from this section
was used to preheat the belt going into the hold section. The hold
section was separated from the heat unit by a short transfer zone
with a canvas curtain. Some steam leakage did occur from the heat
unit into the hold unit.
11
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The IQB unit was equipped with effluent drains on both the heat and
hold units. Although the volume of effluent from each unit was
recorded separately, analysis and reporting of the data were done
on the total.
The second blanching method was IQB with predrying. For predrying,
the vegetables were cycled through a 183 cm. (6 ft.) long by 30.5 cm.
(1 ft.) wide vibrating bed dryer. Air at 71-82 C (160-180 F) (dry
bulb) was passed up through the vegetable bed, and the vegetables
were predried to approximately a 6% weight reduction. A 6% weight
reduction was established based on results in the 1971 study. It
was found that at higher weight reduction irreversible dehydration
occurred (i.e. the product would not rehydrate to initial wet weight)
and product quality was adversely affected (most notably through
excessive skin rupture or excessive browning).
The third blanching method (IQB heat only) utilized only the heat
belt of the IQB unit. Immediately after going through the heating
unit the product was discharged into plastic buckets. Product was
held in the buckets until canning.
The fourth method was deep bed steam blanching. The heat section of
the IQB unit was used for this method also. The product was dis-
charged onto the belt in a 6.4-7.6 cm. (2.5-3 in.) deep layer.
Residence time in the unit was 2.5 min. for all deep bed blanching
trials.
The fifth blanching method evaluated was the commercial method
pipe blanching. The unit consisted of 122-152 m. (400-500 ft.) of
11.4 cm. (4.5 in.) diameter stainless steel pipe. The length was
variable so that the residence time could be adjusted. Product was
metered into the pipe at a preset rate so that the water to product
ratio was constant. After blanching, the product was dewatered at
12
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a dewatering reel and was further processed. The blanch water was
then screened, make-up water was added and the water recycled into
the pipe. Water and vegetables in the pipe blancher were heated
by direct steam injection.
Blanching times used in the IQB heat/hold sections were determined
by making simple observations on the pipe blanching operation. For
peas, it was observed that conventional pipe blanching operation
resulted in peroxidase inactivation and, therefore, peroxidase in-
activation was the criterion for establishing heat/hold times in
IQB. Appropriate heat/hold times were determined by the procedure
described in Lund et_ al^. . For corn and lima beans, water tempera-
ture in pipe blanching was approximately 77 C (170 F) and, conse-
quently, heat/hold times were chosen that would result in a final
corn or lima bean temperature of 77 C. Green beans were also pipe
blanched at 77 C but the conventional IQB process could not be used.
With green beans, the function of blanching is to activate the enzyme
pectin methyl esterase which prevents sloughing of the green bean
following canning. Since the enzyme is inactivated at temperatures
above 82 C (180 F), the IQB heat section could not be heated with
100 C (212 F) steam. Therefore, a steam-air mixture at 79 C (175 F)
was used in the IQB heating section. Heat/hold times were chosen
that would result in an equilibrated temperature of 77 C. For pota-
toes, carrots and beets, a direct comparison to pipe blanching could
not be made since these products are not usually blanched prior to
canning. The only heat treatment these products receive prior to
retorting is in the peeling operation. These products were included
in the IQB and deep-bed experiments, however, since they are blanched
prior to freezing and some processors have experienced undesirable
color changes (particularly with beets and potatoes) which can be
avoided by blanching after slicing or dicing. Blanching conditions
were chosen such that peroxidase was inactivated. For deep-bed
blanching, all vegetables were blanched for 2.5 minutes, the maximum
13
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residence time of the IQB heat section. Blanching conditions for
all vegetables are shown in Table 3.
Table 3. BLANCHING TIMES AND TEMPERATURES3
Commodity
Peas
Corn
Lima beans
Green beans
Potatoes
Carrots
Beets
IQB
30 sec/100 C heat
45 sec hold
20 sec/100 C heat
30 sec hold
20 sec/100 C heat
80 sec hold
20 sec/82 C heat
80 sec hold
60 sec/100 C heat
60 sec hold
45 sec/100 C heat
60 sec hold
45 sec/100 C heat
60 sec hold
Heat only
30 sec/100 C
20 sec/100 C
20 sec/100 C
Deep bed
2.5 min/100 C
2.5 min/100 C
2.5 min/100 C
2.5 min/82 C
2.5 min/100 C
2.5 min/100 C
2.5 min/100 C
Pipe
4 min/93 C
1.5 min/77C
4 min/77 C
2 min/77 C
All time/temperature combinations resulted in negative peroxidase except
for green beans. Time/Temperature (C).
For each experimental run, three 9.09 kg. (20 Ib.) batches of the
vegetable were treated by one of the four steam blanching methods.
Initial weight, weight after drying (if the product was predried),
and weight after blanching were recorded. For each 9.09 kg. run, all
waste water generated by processing the vegetable in the blancher was
measured. A composite sample of the waste water was subjected to
analysis for the following: 1) BOD5> 2) COD, 3) total solids, 4)
suspended solids, 5) soluble phosphorus, 6) total phosphorus, 7)
total organic nitrogen, 8) NHj-Nitrogen, 9) NO^Nitrogen, 10) N02~
Nitrogen, 11) volatile solids, 12) suspended volatile solids, and
14
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13) pH. Part of the analyses were performed by the Wisconsin Depart-
ment of Natural Res
analyses were used
ment of Natural Resources. In all cases the standard methods for
,6
In order to report waste water generation on the basis of amount of
product processed, a blank was determined for each run by operating
the equipment with the steam on and the belts moving for a period
of time equal to the time to process the 9.09 kg. lot. Equipment
effluent (due to heat losses from the equipment, heating the belt and
any water carried in the steam line) was measured and this value sub-
tracted from the volume generated during the actual run. All analysis
values were corrected by the resulting dilution factor. Immediately
following blanching, samples were filled into 303 x 406 cans to the
appropriate fill weight, brine added, cans sealed and retorted in a
Steritort following the heat/cool process used in the canning plant.
For the pipe blancher, effluent was collected at the dewatering reel
and subjected to the same analyses as other samples. Water usage was
monitored by a water meter in the water make-up line and was recorded
daily. By knowing the daily case pack on the line, the liters of
water per case of product could be calculated. Since the pipe
blanching water was heated by direct steam injection, the effluent
generated by the system was larger than that calculated from the
water make-up readings. To adjust for the steam condensation in
heating the product up, it was assumed that 4.23 kg. (9.3 Ib.) of
steam would condense for every 45.5 kg. (100 Ib.) of product being
heated 38.0 C (100 F). This resulted in 91.7 liters of steam con-
densation per kkg. of product (22 gal/ton). This value has been
added to all pipe blancher values as calculated from water meter
readings. Waste generation reported for the pipe blanching system
will still be low since this does not account for heat losses from
the piping system. However, for the system we monitored heat losses
would probably not contribute more than 8.3-20.9 l./kkg. (2-5 gal/ton)
of product processed.
15
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To insure that representative samples of waste water were being
collected from the pipe blancher, on some occasions (at least two
days for each vegetable), water samples were collected at two-hour
intervals. Results indicated that within two hours of start-up the
blancher water was in steady state. Therefore, all samples were
taken at least two hours after start-up. For later evaluation and
comparison, several cases of canned vegetables processed at the same
time the experimental samples were processed were brought to the
laboratory.
PRODUCT EVALUATION
After blanching, the product was hand packed into 303 x 406 cans,
boiling water and the appropriate volume of concentrated brine were
added and the cans were sealed. The cans were then thermally proc-
essed in a Steritort using rotation speed and heat/cool times iden-
tical to those used in the canning plant. Product was then stored
at 32 C (90 F) along with conventionally processed product which had
been obtained from the canning plant. Product evaluations were con-
ducted at 1, 3, 6 and 9 months' storage. The tests performed on
each product are shown in Table 4. Standard procedures were followed
for all tests. The method of Van Buren et al. was used for the
slough test on green beans. At each evaluation a five-can subsample
for each experimental process and conventional process was analyzed.
Product quality was assessed by triangle taste test comparing each
experimentally processed product to the corresponding control process
product (canned product obtained from the canning plant). Taste
testing was conducted in the Sensory Evaluation Laboratory of the
Department of Food Science using personnel who were trained in
sensory evaluation. Differences could be assessed on the basis of
color, texture or flavor and preference was noted. To streamline
the presentation of sensory evaluation data, two pieces of informa-
tion were generated. The first consists of three numbers separated
16
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Table 4. PRODUCT EVALUATION TESTS
Test
Taste panel
Can vacuum
Drained weight
Brine sediment
Slough
Percent splits
Peas
X
X
X
X
X
Corn
X
X
X
Lima
beans
X
X
X
Green
beans
X
X
X
X
X
Pota-
toes
X
X
X
Carrots
X
X
X
Beets
X
X
X
by slashes such as 10/5/5. The first number (10) is the number of
correct judgments which preferred the experimentally blanched canned
product; the second number (5) is the number of correct judgments
which preferred the control sample; and the last number (5) is the
number of correct judgments which showed no preference. The second
piece of information was the level of distinction between samples.
There was either no significant difference (NS) or differences
were identifiable at the 0.1%, 1% or 5% level.
17
-------
SECTION VI
RESULTS AND DISCUSSION
FLOW VARIABILITY OF BLANCHING WASTES
During the processing season daily water meter readings were recorded
for water usage in the pipe blancher for peas, corn, and green beans.
Examination of the data showed that the most consistent characteristic
was the extreme variability in water used per case or ton of vegetable.
The data were so scattered that it is tenuous at best to draw con-
clusions. However, in the hope of comparing IQB to pipe blanching,
average water usage rates were calculated. An example of variability
of data is the range of data reported for green bean blanching. On
8/24/72 there was a reported 24.2 l./case (6.4 gal/case) water usage
in the pipe blancher; whereas on 9/16/72 only 0.45 l./case (0.12 gal/
case) was recorded. This is over a 50-fold difference! In pea
blanching, on 6/27/72, 6.6 l./case (1.75 gal/case) was recorded for
the pipe blancher compared to 0.33 l./case (0.088 gal/case) on
7/19/72, a 20-fold difference. This tremendous variability con-
tributes to many misinterpretations regarding water usage in blanch-
ing operations. One factor responsible for variability is incomplete
knowledge of the blanching system. In our case we were not informed
that the blancher could be filled from two separate sources, one at
the inlet end and one at the discharge end. Consequently, we only
monitored water inlet from one source. Once this was recognized we
were able to screen the data to assure -that a representative value
was reported. A second factor responsible for variability of flow is
the lack of control on the blanching unit operation. Many times the
18
-------
blancher is not equipped with a flow regulating device but rather
there is just a water line bringing water into the system. The
foreman or worker merely opens a water valve to the blancher and has
no guidance as to the appropriate flow rate to use. Therefore, on
some occasions flow is very high, while on others it is very low.
In addition to the variability of flow between days, there is also
variability of flow within a day. An example of water flow from
blanching during one day of processing for peas, corn, green beans
and lima beans is shown in Table 5. The percent total solids of the
blancher effluent is also given. It can be seen that there is con-
siderable variability in the water usage pattern throughout the
processing day. This variability reflects the cyclic nature of the
blanching operation in that the blancher is generally drained and
refilled several times during the operating day. This cleanup is
necessitated by the fact that the solids leached from the tissue
during blanching undergo oxidative and thermal degradation to very
flavorful compounds. These compounds can produce off-flavor in the
final product unless they are removed periodically. For peas the
blancher was refilled every 6-8 hours, for corn every 12 hours, and
for lima beans every six hours. For green beans the blancher was
refilled every six hours but no make-up water was added between re-
fills. Under these conditions the total solids in the blanch water
varies considerably, for example, from 0.55% TS to 1.35% TS. With
the other vegetables the % TS is kept relatively constant by the
addition of make-up water.
The data reported in Table 5 for lima beans are from the 1971 study.
No data are available on water usage for lima beans for 1972 due to
a change in blanching conditions. In 1971, the water make-up rate
was approximately 76 l./case (20 gal/case), about ten times higher
than that reported for the other vegetables. At the end of the 1971
19
-------
Table 5. HOURLY MAKE-UP FLOW RATES AND TOTAL SOLIDS CONTENT OF PIPE
BLANCHER WATER FOR PEAS, CORN, LIMA BEANS AND GREEN BEANS
Time
(hrs)
2
2.5
3
3.5
4
6
8
10
12
14
16
18
1
Peas
% TS l./hr
2.31 719
2.15 590
2.24 795
2.90 636
2.90 689
2.70 708
Corn
% TS
2.47
2.58
2.50
2.30
2.05
1.09
2.24
3.00
2.79
2.12
2.26
1.95
l./hr
1703
1363
1363
1363
1817
1249
1400
1400
4126
265
2725
1779
Lima
beans
% TS l./hr
0.59 24600
0.39 20250
0.62 30470
0.43 15030
0.37 20530
Green
beans
% TS 1
0.71
1.12
0.63
1.01
0.97
0.55
1.23
1.35
./hr
8880
0
6230
0
0
9750
0
0
processing season this observation was made to the plant personnel
who immediately sought to correct the situation for 1972. The high
water usage rate was the result of the foaming problem associated with
lima bean blanch water. In 1972, several corrective actions were
taken: 1) use of an antifoam agent in the blanch water, 2) use of
hard water instead of soft and 3) maintenance of a full reservoir
prior to the pump (eliminated air entrapment). Since the water
make-up line was hard water and fed several pieces of equipment si-
multaneously, it was impossible to monitor water addition rates. How-
ever, after conversations with plant personnel, it was estimated that
water usage rates for lima beans were about the same as those for
corn.
20
-------
CONDENSATION OF RAW DATA
In this type of study volumes of raw data can be obtained and much
of it can, in turn, be multiplied considerably by calculations. In
order to simplify the examination of data and to reach the really
pertinent information obtained in this study, the raw data were con-
densed and only the pertinent calculations were performed. Many
more calculations can be done but they do not serve to demonstrate
more effectively the results contained herein.
The raw data for each of the blanching runs are given in the Appendix
in Tables Al - A14. The first table for each product presents the
physical characteristics of the run such as belt loadings, effluent
generated (expressed as l./case), product yield and solids lost as
product. "Belt loading" results will be discussed in a later sec-
tion. "Effluent generated" was calculated from the volume of waste
collected per unit of raw product. "Product yield" is the ratio of
blanched weight to initial weight times one hundred. "Solids lost
as product" represents the solids in the blanch water expressed on
the basis of product equivalents. For this calculation it was
assumed that peas were 20% total solids, corn was 25%, lima beans
were 32.5%, green beans were 10%, potatoes were 20.2%, carrots were
11.8% and beets were 12.7%. These values are from USDA Handbook
No. 8.
The second table presenting raw data on each blanching run for each
product characterizes the effluent. All of the data are expressed
as ppm or % and represent the concentration of the particular com-
ponent in the effluent» A more convenient way of expressing these
data for discussion purposes is to express the water characteristics
on the basis of kkg. of processed product. This was done and selected
characteristics will be presented in later discussions.
21
-------
The notation used in the tables to describe the blanching treatment
is relatively straightforward. IQB stands for individual quick
blanch, the "-0" or "-number" represents the predrying treatment (0
means no predrying; number expresses the % weight reduction in pre-
drying), the "-sec" represents the heat only process of IQB and deep
bed represents deep bed steam blanching. Pipe refers to pipe blanch-
ing, the control.
Examination of the raw data shows that several variables had no
effect on blanching characteristics of the product. For peas there
did not appear to be an effect due to variety or harvest date on
blanching characteristics. Therefore, the data within one blanching
treatment could be averaged to simplify presentation. Similarly with
corn, there did not appear to be an effect of harvest date. There-
fore, the data were averaged within each blanching treatment. Lima
beans, green beans, potatoes, beets and carrots also showed no har-
vest date effect. Therefore, averages are used in discussing the
results. It should be pointed out that the variable harvest date
is not the same as the variable maturity. For example, although
corn may be harvested on different dates it may be of the same ma-
turity and consequently there can still be a maturity effect. With
corn in particular, it might be suspected that there would be a dif-
ference in blancher effluent for mature versus immature corn.
Although several parameters were measured on the blancher effluent
only a few will be discussed. Probably the most important parameters
are BOD^, total organic nitrogen and total phosphorus since the
relative concentrations of these three components are used to assess
the response of the waste to biological waste treatment. Consequently
in discussing the data, only these three parameters will be discussed.
22
-------
PEA BLANCHING
A summary of the pea blanching data is given in Table 6.
Table 6. SUMMARY OF PEA BLANCHING DATA3
Blanching
treatment
IQB-6.9
IQB-0
30 Sec
Deep bed
Pipe
Effluent
generation
(l./kkg)
146
225
209
313
384
BOD5
(kg/kkg)
1.8
2.6
2.5
4.3
3.0
Total
organic
nitrogen
(kg/kkg)
0.09
0.13
0.13
0.22
0.17
Total
phosphorus
(kg/kkg)
0.02
0.04
0.03
0.05
0.05
Product
yield
(%)
88.8
89.3
90.4
83.3
--
Solids
lost as
product
a)
1.53
2.07
2.09
3.11
--
Expressed per kkg of blanched product. See Tables Al and A2 for
complete data.
IQB-6.9 means IQB with a 6.9% weight reduction prior to blanching.
IQB-0 means IQB without predrying.
30 Sec means heat section only of IQB.
Deep bed means deep bed steam blanching.
Pipe means pipe blanching.
The first important observation is that all of the steam blanching
methods resulted in less effluent generation than pipe blanching.
Predrying by an average of 6.97, weight reduction reduced waste genera-
tion by 62% while deep bed blanching reduced the waste stream by 18%.
As expected, predrying showed less generation of waste than IQB or
30 sec. heat treatments. Predrying the surface of the pea allowed
the condensed steam to rehydrate the surface rather than running off.
The IQB-0 and 30 sec. heat treatments resulted in nearly the same
total effluent generation indicating that most of the effluent is
generated in the heat section of IQB from steam condensation.
The value of 225 l./kkg (54 gal/ton) reported here for IQB-0 agrees
quite well with the 200 l./kkg (48 gal/ton) for steam blanching peas
23
-------
g
as reported by Rails et al. and with the theoretical value obtained
when a mass balance is performed on the unit operation. In Rails
et al. study the loading rate was only 2 kg/nr (0.4 pound/ft ) of
belt suggesting that they had the equivalent of an IQB heat stage.
The residence time, however, was much longer than the 30 sec. used
in IQB.
The deep bed steam blanching treatment resulted in 313 l./kkg (75
gal/ton product), nearly 50% more than IQB blanching. The greater
effluent generation is due to two factors: 1) overheating of some
of the tissue resulting in greater juice loss and 2) a lower surface
water holding capacity of the heated bed of peas. The first factor
is evident from the higher BOD^, nitrogen and phosphorous values
reported for the deep bed treatment. Also, the solids lost as
product is nearly 50% more than for IQB. The second factor, lower
water holding capacity of the bed of peas, is a result of the higher
mass average temperature of the peas in the deep bed treatment.
With the residence time of 2.5 minutes the bed temperature was much
higher and consequently the viscosity of the water and the surface
tension of water were lower resulting in more water running off.
The 384 l./kkg (92 gal/ton) reported here is much lower than other
values reported for water blanching systems. Weckel et al. reported
a waste water generation of 1420 l./kkg (340 gal/ton) for a pipe
blanching while Rails et al.8 reported 4170 l./kkg (1000 gal/ton)
for a draper-type water blancher. The value reported here reflects
a very important concept recognized by the canning plant personnel.
They have cut back the water make-up on a regular basis while con-
tinuously checking product quality. This has allowed them to cut
water usage drastically through control on the process. The high
value reported by Rails et al.& may not necessarily reflect excessive
waste generation with the draper-type blancher. Rather it may re-
flect the batch-type nature of the way in which the experiment was
24
-------
conducted. Perhaps more peas could have been processed in the
blancher before the water had to be changed. Also, a feed and bleed
system would reduce water usage.
The BOD- reported here for steam and pipe blanching corresponds quite
* Q
well to the data of Rails et al. . They reported a COD of 8.3 kg/kkg
(16.6 Ib/ton) for steam blanching and if we assume a BOD/COD ratio of
0.60 this would result in a BODg of about 5 kg/kkg (10 Ib/ton). The
BOD/nitrogen/phosphorous ratio was surprisingly constant with an
average of 82/4.4/1 (range 55-117/3.1-7.6/1.This indicates that this
waste has an adequate carbon to nitrogen to phosphorous ratio for biological
treatment.
Finally, the product yield is given in Table 6. Product yield was
quite constant between the IQB treatments but deep bed steam blanch-
ing resulted in considerably greater loss of yield. For deep bed
steam blanching this lower yield is due to tissue breakdown and
lower water holding capacity of the peas, as explained earlier.
For IQB blanching most of the weight loss is also a result of the
lower moisture holding capacity of the surface. From experiments
done in 1971, a cold pea can hold up to 15% by weight as surface
moisture. After blanching, the surface is nearly dry even though
steam has condensed on the surface. The hot surface can hold only
up to 6% by weight as water and thus loss of surface moisture would
account for up to 9% weight loss.
The product yield value would appear to be too low for economic con-
sideration of IQB; however, the process should be evaluated primarily
on the basis of solids lost since this value represents true product
loss. Product yield reflects the loss of surface water as well as
product loss. It would be anticipated that hot water blanching
9
would result in even greater solids loss as reported by Lee .
25
-------
The results of objective evaluation of peas is shown in Table 7.
It is noticed that all cf the can vacuum values for the experimentally
blanched samples are higher than that for pipe blanched samples. This
is due to the fact that the fill water temperature was higher in the
experimentally blanched samples. In the laboratory the fill water
temperature was near 96 C (205 F) whereas in the canning plant it
was 82-88 C (180-190 F). This difference could account for the
difference in can vacuum. This demonstrated, however, that peas
could be successfully steam blanched prior to canning and that there
was adequate air removal from the tissue. The can vacuum decreased
slightly upon storage, as expected.
The drained weights of all steam blanched samples were higher than
those of the control. This was not likely the result of the blanching
treatment but rather was the result of a slight overfill. The fill
weight was 292.5 g. (10.3 ounces) and the resulting drained weight
averaged 320.9 g. (11.3 ounces), a 28 g. (one ounce) weight gain
upon retorting and cooling.
Brine sediment values reflect a problem associated with predrying
prior to IQB. The brine sediment values were consistently higher
for the predried samples. This is due to skin splitting that occurs
during predrying and subsequently comes off in the agitated retort
operation. Compared to pipe blanching, the other steam blanching
systems are quite acceptable.
Finally, the percent split data are presented. Although the percent
split is higher for the steam blanched samples, this apparently was
not detrimental to product quality. The brine sediment value did
not seem to reflect the split damage. Greater percent splits in
steam blanching compared to water blanching may reflect the dif-
ference in heating rates. With steam blanching the temperature
increases very rapidly resulting in a rapid expulsion of tissue
26
-------
Table 7. SUMMARY OF OBJECTIVE EVALUATION OF PEAS
Blanch-
ing
treat-
ment
IQB-6.9
IQB
30 Sec
Deep
bed
Pipe
IQB-6.9
IQB
30 Sec
Deep
bed
Pipe
IQB-6.9
IQB
30 Sec
Deep
bed
Pipe
Can Vacuum
(cm. Hg. vacuum)
Months of storage
1 3 6 9
Avg.
34.8
34.0
29.7
31.5
21.6
320.4
316.4
315.8
J37.4
295.1
Range
26.4-39.9
27.2-37.3
21.6-36.6
23.4-36.8
17.0-30.0
312.1-324.3
311.0-323.2
308.4-320.1
326.6-343.6
285.7-305.6
Avg.
31.5
32.3
29.5
30.7
21.6
326.8
319.2
313.5
337.4
301.0
Range
20.6-38.4
20.8-41.1
18.3-36.8
23.4-34.5
13.7-28.4
Avg.
31.8
32.0
28.4
28.4
20.8
Range
22.1-36.8
22.4-38.4
21.6-31.8
19.8-33.3
16.0-26.9
Drained Weight
(g.)
315.8-337.1
311.3-326.9
307.6-317.5
329.4-345.3
291.1-307.0
322.6
318.6
312.7
332.3
301.6
315.8-328.0
314.4-320.9
309.0-315.5
325.7-337.7
293.4-305.6
Avg.
32.0
30.2
29.7
29.5
17.5
320.4
320.1
315.0
334.3
302.5
Range
27.9-36.1
24.4-36.8
25.4-31.8
26.4-31.5
10.2-24.9
313.0-324.6
311.5-328.0
309.8-318.4
326.6-341.9
299.1-305.9
Brine Sediment
m
6.29
3.82
4.09
3.96
5.30
5.05-8.18
3.69-3.91
2.97-5.06
2.45-6.12
3.23-8.76
7.23
4.23
3.73
3.83
3.59
5.05-10.36
3.88-4.56
2.81-5.23
3.45-4.37
2.36-5.27
5.41
3.81
3.41
4.07
4.05
5.24-5.57
3.44-4.17
2.98-3.81
3.28-5.06
2.15-7.00
4.59
3.38
4.80
3.13
3.89
4.46-4.72
3.33-3.43
1.79-8.30
2.88-3.39
2.16-6.08
Each average consists of at least nine observations.
27
-------
Table 7 (continued). SUMMARY OF OBJECTIVE EVALUATION OF PEAS'
Blanch-
ing
treat-
ment
IQB-6.9
IQB
30 Sec
Deep bed
Pipe
Splits in Peas
(%)
1
Avg.
38
28
36
40
18
Months of Storage
3 6
Range
30-48
26-30
29-40
32-56
14-29
Avg.
35
41
36
33
22
Range
29-39
39-43
29-43
28-39
13-29
Avg.
35
30
27
28
21
9
Range
26-45
24-34
21-37
19-37
14-27
Avg.
30
24
30
29
20
Range
26-35
19-30
20-40
23-34
16-25
Each average consists of at least nine observations.
gases. This sudden expansion of gases may fracture in the peas
resulting in eventual splitting. With water blanching, on the other
hand, the temperature rise is slow enough to allow tissue gases to
diffuse out of the tissue without developing excessive pressures.
A summary of the subjective evaluation of peas is given in Table 8.
From these data it is concluded that steam blanching resulted in a
canned pea product at least as good as that produced with pipe blanch-
ing. In those cases where there was a significant difference, the
steam blanched product was generally preferred.
In conclusion, the study with peas indicates that IQB can be success-
fully used for pea blanching with a 40% decrease in liquid waste generation
compared to pipe blanching. Compared to deep, bed steam blanching,
IQB produced 28% less effluent and less product loss. IQB with pre-
drying is not recommended due to significant increases in brine
sediment. Product quality as evaluated by objective and taste panel
tests was at least as good for IQB as for pipe blanching.
CORN BLANCHING
A summary of the corn blanching data is given in Table 9.
28
-------
Table 8. SUMMARY OF SUBJECTIVE EVALUATION OF PEAS
Blanching
treatmenta
IQB-6.25-4-A1S
IQB-O-4-Als
30 Sec-4-Als
Deep bed-4-Als
IQB-7.0-3-Ala
IQB-O-3-Ala
30 Sec-3-Ala
Deep bed-3-Ala
IQB-7.5-Perf.
IQB-0-Perf.
30 Sec-Perf.
Deep bed-Perf.
Storage time (months)5
1369
0.1%
8-4-4
5%
8-3-2
NS
0.1%
13-4-3
5%
5-6-2
NS
1%
4-5-5
NS
NS
NS
NS
NS
1%
8-5-3
1%
9-4-2
0.1%
12-3-2
NS
NS
NS
NS
NS
_.
NS
NS
0.1%
11-2-3
1%
6-3-6
0.1%
9-2-3
0.1%
7-6-1
0.1%
5-7-7
NS
NS
1%
2-6-9
1%
4-6-7
NS
_
0.1%
7-5-8
0.1%
7-6-7
0.1%
12-5-3
0.1%
12-3-4
5%
3-7-6
NS
5%
5-5-4
NS
NS
NS
NS
NS
IQB-6.25 means IQB with a 6.25% weight reduction prior to blanching.
IQB-0 means IQB without predrying.
30 Sec means heat only stage of IQB.
Deep bed means deep bed steam blanching.
4 or 3 refers to sieve size; Perfection was sieve size 3, 4 and 5.
Als means Alsweet; Ala means Alaskan; Perf. means Perfection.
3Each sample was compared to a pipe-blanched, canned control. The control
was canned the same day as the experimental sample. The top number is
the level of significance and the bottom three numbers represent number
of judges preferring experimental sample, control and no preference,
respectively. NS means no significant difference.
29
-------
Table 9. SUMMARY OF CORN BLANCHING DATA
Blanching
treatment
IQB-7.5
IQB-0
20 Sec
Deep bed
Pipe
Effluent
generation
Q./kkg)
86
125
125
163
730
BOD5
Ckg/kkg)
1.4
2.7
3.0
4.4
4.9
Total
organic
nitrogen
(kg/kkg)
0.017
0.039
0.037
0.049
0.089
Total
phosphorus
(kg/kkg)
0.008
0.020
0.019
0.028
0.034
Product
yield
(%)
93.1
97.1
97.4
94.2
--
Solids
lost as
product
a)
0.81
1.61
1.52
2.42
--
«
Expressed per kkg of blanched corn. See Tables A3 and A4 for complete
data.
bIQB-7.5 means IQB with a 7.5% weight reduction prior to blanching.
IQB-0 means IQB without predrying.
20 Sec means heat section only of IQB.
Deep bed means deep bed steam blanching.
Pipe means pipe blanching.
As with pea blanching, all of the steam blanching methods produced
less effluent than pipe blanching. IQB without predrying reduced
effluent generation by 33% compared to pipe blanching while a 7.5%
weight reduction prior to IQB reduced effluent generation by 88%.
The effluent generated per ton of corn is considerably less than that
for peas because of the difference in the nature of the surface of
the two vegetables. Cut corn surfaces expose starch which upon heat-
ing can absorb water resulting in less water loss. On the other
hand, the 8005 for corn was about the same as that for peas indi-
cating that water that did drain off corn carried with it more
solids. In pipe blanching, water usage for corn was nearly double
that for peas. This reflects the fact that with corn, the blanching
process is primarily a wash step to remove reducing sugars and other
components that may contribute to brown color development during
thermal processing. In some plants, corn is not blanched prior to
canning. Weckel et al. reported an average of 1043 l./kkg
30
-------
(250 gal/ton) for pipe blanching corn. As with' peas, deep bed steam
blanching resulted in greater effluent generation than IQB but it
was still considerably less than pipe blanching.
The BOD/N/P ratio for corn averaged 151/2.1/1 (range 88-237/1.5-2.9/1)
indicating that the waste may be low in nitrogen for biological
treatment. From Table A4 the BOD/COD ratio was 0.78. Soderquist
et al. reported a BOD/COD ratio of 0.75 for corn wastes. That
figure, however, included waste generated at unit operations in ad-
dition to blanching.
With respect to product yield there are some interesting observa-
tions. First, with predrying the product yield is lower than with
IQB without predrying. This reflects the fact that the corn surface,
once dehydrated, is very difficult to rehydrate and thus this yield
reflects losses of product solids and loss of reabsorbing capacity
of the surface. Deep bed steam blanching resulted in greater product
loss primarily through solids lost in the effluent.
Table 10 presents the results of the objective evaluation on steam
blanched and pipe blanched corn. As with peas, can vacuum for the
steam blanched samples is higher than that for the pipe blanched
sample. This reflects the lower water fill temperature used in the
canning plant compared to the laboratory pilot plant. There was no
significant difference in drained weight between any of the samples.
A summary of the subjective evaluation of corn is given in Table 11.
There appears to be a significant difference between steam blanched
and pipe blanched samples but the preference is not consistent. It
was observed that the steam blanched samples were darker in color
than the pipe blanched samples attesting to the fact that the blanch
step is primarily a wash step for corn. This darker color, however,
did not manifest itself in consumer preference meaning that perhaps
31
-------
blanching does not have to serve as a wash step if the consumer cannot
detect the color difference.
Table 10. SUMMARY OF OBJECTIVE EVALUATION OF CORN3
Blanch-
ing
treat-
ment
IQB-7.5
IQB
20 Sec
Deep bed
Control-
IQB-7.5
IQB
20 Sec
Deep bed
Control
Can Vacuum
(cm. Hg. vacuum)
Months of Storage
1 3 6 9
Avg.
26.9
31.8
28.2
26.4
23.6
327.7
324.6
325.5
331.7
327.2
Range
21.6-30.7
29.0-35.1
23.6-36.6
22.6-31.8
18.5-28.7
326.9-294.1
322.6-327.7
320.9-330.9
330.3-332.8
310.4-343.1
Avg.
27.9
32.5
32.3
31.0
18.5
Di
328. Ob
317.8
317.2
326.9
304.4
Avg.
21.8
26.7
23.6
20.6
17.5
rained V
(g)
326.9
318.4
315.8
327.7
324.6
Range
15.2-27.4
20.8-34.8
19.1-31.8
14.5-31.2
16.5-19.6
/eight
321.8-330.3
315.8-320.1
314.7-317.2
322.6-330.3
315.8-339.4
Avg.
23.1
27.7
27.7
24.6
22.6
322.9
323.5
321.2
330.3
322.1
Range
21.6-25.4
25.4-32.0
22.6-34.3
51.8-31.8
17.8-26.2
317.8-329.4
316.1-328.3
320.6-322.1
328.3-332.3
313.5-337.1
o
, Each average consists of at least nine observations.
Only one series of samples was evaluated after three months' storage.
In conclusion, IQB and deep bed steam blanching both result in
drastic reductions of effluent generation in corn blanching. How-
ever, in both cases a darker product resulted after retorting. To
maintain a bright golden yellow color, corn would have to be thor-
oughly washed prior to steam blanching. This wash step, in turn,
defeats the purpose of steam blanching since the wash step would
create another high volume-low load effluent steam. Therefore, the
32
-------
Table 11. SUMMARY OF SUBJECTIVE EVALUATION OF CORN
Blanching
treatmenta
IQB-7.5
IQB-0
20 Sec
Deep bed
IQB-7.5
IQB-0
20 Sec
Deep bed
IQB-7.5
IQB-0
20 Sec
Deep Bed
Storage time (months )b
136 9
1%
4-10-4
5%
3-8-5
NS
5%
3-8-3
0.17.
8-13-1
NS
NS
NS
1%
8-5-4
17,
10-8-0
0.17.
18-3-1
0.17.
17-2-0
17.
4-7-3
0.17.
0-11-3
17.
9-4-1
0.17.
6-9-1
_.
m*
..
_.
--
0.17.
2-17-4
NS
NS
NS
0.1%
2-12-7
NS
0.17.
3-7-2
17.
7-9-2
0.17.
10-6-5
1%
9-7-2
NS
0.17.
11-7-2
NS
57.
3-4-6
1%
2-9-4
NS
17.
6-6-5
17.
7-3-6
0.17.
10-6-2
NS
0.17.
18-3-4
0.17.
5-16-4
0.17.
16-3-3
0.1%
11-5-3
IQB-7.5 means IQB with 7.57. weight reduction prior to blanching.
IQB-0 means IQB without predrying.
20 Sec means heat only stage of IQB.
Deep bed means deep bed steam blanching.
Each sample was compared to a pipe-blanched, canned control.
The control was canned the same day as the experimental sample. The
top number is the level of significance and the bottom three numbers
represent number of judges preferring experimental sample, control
and no preference, respectively. NS means no significant difference.
advantage of producing a bright yellow corn must be weighed against
the disadvantage of creating an effluent stream and the cost of its
subsequent treatment. Since blanching of corn must be done when
corn is packed into No. 10 cans, there is still a use for steam
blanching.
33
-------
LIMA BEANS
Lima bean blanching results are summarized in Table 12.
Table 12. SUMMARY OF LIMA BEAN BLANCHING DATA3
Blanching
treatment**
IQB-5.0
IQB-0
20 Sec
Deep bed
Pipe
Effluent
generation
U./kkO
67
171
133
238
821
BODs
fke/kkg)
0.35
1.7
2.4
3.5
0.65
Total
organic
nitrogen
(kg/kkR)
0.02
0.12
0.06
0.17
0.02
Total
phosphorus
(kg/kkg)
0.004
0.02
0.015
0.04
0.01
Product
yield
(%)
97.5
93.4
96.7
88.7
--
Solids
lost as
product
a)
0.24
0.86
0.54
1.38
--
Expressed per kkg of blanched product. See Tables A5 and A6 for
complete data.
3IQB-5.0 means IQB with a 5.0% weight reduction prior to blanching.
IQB-0 means IQB without predrying.
20 Sec means heat section only of IQB.
Deep bed means deep bed steam blanching.
Pipe means pipe blanching.
Results with lima beans parallel those obtained with peas and corn.
The effluent generation values are similar to those reported for
corn in Table 9 and reflects the water holding capacity of the sur-
face of the lima bean. In lima bean processing the blanch step
serves to partially rehydrate the dry lima bean seeds.
The pipe blanching method produced 821 l./kg (197 gal/ton) compared
to only 171 l./kg (41 gal/ton) for IQB; IQB reduced effluent by 79%.
Predrying reduced the effluent to only 8% of that for pipe blanching.
The BOD/N/P ratio averaged 97/4.8/1 (range 32-205/1.1-7.8/1) indicating
that lima bean blancher effluent has an adequate nutrient balance for
34
-------
biological waste treatment. The BOD/COD ratio was 0.76 (calculated
from Table A6). Product yield figures indicate that lima beans re-
hydrate readily after the predrying step since the yield is greater
than that for the other steam blanching methods. The difference
between the yield values for IQB-0 and 20 sec reflect product loss
and liquid loss in the hold section during IQB. The only difference
between these two runs is the fact that the 20 sec experiment did
not include the hold section. The liquid loss occurring in the hold
section is also reflected in the higher effluent generation value
reported for IQB-0 compared to 20 sec. Deep bed steam blanching
resulted in the lowest yield and is partially accounted for in the
solids lost. The other loss is accounted for in the decreased water
holding capacity of the surface due to a higher mass average tem-
perature of the deep bed blanched lima beans.
Results of the objective evaluation of lima beans is given in Table
13. It can be seen that can vacuum of all of the steam blanched
samples is considerably lower than that for pipe blanched, canned
product. This may have been due in part to can overfill in the
experimental samples. Notice that most of the drained weights are
greater for the experimentally blanched samples indicating that the
can was overfilled. Upon retorting the lima bean absorbs water and
expands. This can result in decreased can vacuum. Thus, the lower
can vacuum for the steam blanched samples does not necessarily re-
flect poor tissue gas removal. The somewhat higher (8-10%) drained
weights for the steam blanched samples could be corrected by
filling at approximately 227-241 g.(8-8.5 ounces) rather than the
current 256 g. (9.0 ounces) fill weight. Proper drained weight
would then be achieved following retorting and can vacuum would
probably be higher.
Although it was not recorded, there appeared to be more skins and
suspended solids in the IQB predried sample. This was presumably
35
-------
Table 13. SUMMARY OF OBJECTIVE EVALUATION OF LIMA BEANS
Blanch-
ing
treat-
ment
IQB-5.0
IQB
20 Sec
Deep
bed
Pipe
IQB-5.0
IQB
20 Sec
Deep
bed
Pipe
Can Vacuum
(cm. Hg. vacuum)
Months of Storage
1 3
Avg.
15.0
15.7
12.7
12.4
29.7
Range
11.4-21.6
9.7-21.6
12.2-13.0
6.4-20.3
28.7-31.2
Avg.
17.0
17.8
17.0
16.3
30.5
Range
15.2-19.1
13.5-21.8
14.5-19.6
14.0-19.1
29.7-31.8
6 9
Avg.
17.0
18.8
17.8
13.7
28.7
Range
10.2-20.3
14.7-22.6
14.2-21.1
10.2-17.9
28.2-29,2
Avg.
14.7
16.3
15.7
14.5
27.4
Range
11.4-17.8
11.9-20.6
15.2-16.3
8.9-17.8
26.7-28.4
Drained Weight
395.3
307.3
296.8
341.7
324.0
381.4-413.6
299.6-315.0
277.8-315.8
338.7-343.5
298.2-364.9
568.3
J17.8
J03.6
J41.1
J07.9
(g.)
362.3-373.2
295.1-340.2
283.4-323.5
335.0-343.9
298.2-317.2
386.0
338.5
298.2
341.1
305.6
372.8-394.9
296.8-380.3
279.7-317.5
i
336.9-345.3
293.7-311.8
400.4
334.3
301.3
344.2
307.6
374.5-414.7
299.9-368.6
278.6-324.0
338.0-349.7
306.7-319.8
Each average consists of at least three observations.
due to the rupture of skins during drying which were released during
the agitated cook. On this basis it is doubtful if IQB with pre-
drying is an acceptable process.
Subjective evaluation of lima beans is presented in Table 14. There
was no clear trend in preference for either steam blanched or pipe
blanched product. This probably reflects the fact that people
usually do not have a specific idea of what good lima beans are
supposed to taste or look like. The conclusion can be made that
there is probably a difference but that it was not a striking enough
36
-------
Table 14. SUMMARY OF SUBJECTIVE EVALUATION OF LIMA BEANS
Blanching
treatment3
iqs-5.0
IOB-0
20 Sec
Deep Bed
IQB-0
20 Sec
Storage Timeb (months)
1369
0.17.
9-6-1
0.17.
8-10-0
57,
6-7-2
NS
NS
NS
0.17.
8-6-3
0.1%
7-8-2
NS
NS
0.17.
6-8-5
0.17.
7-4-7
17.
8-5-4
NS
1%
4-7-6
0.17.
8-4-9
NS
0.17.
6-5-5
NS
0.17.
5-4-11
0.17.
5-4-11
0.17.
5-4-11
NS
0.17.
4-6-6
IQB-5.0 means IQB with a 5.07. weight reduction prior to drying.
IQB-0 means IQB with no predrying.
30 Sec means heat only stage of IQB.
Deep bed means deep bed steam blanching.
Each sample was compared to a pipe-blanched, canned sample. The control
was canned the same day as the experimental sample. The top number is
the level of significance and the bottom three numbers represent number
of judges preferring experimental sample, control and no preference,
respectively. NS means no significant difference.
difference to allow development of a preference. There is no justi-
fication for discarding any of the steam blanching methods based on
subjective evaluation.
In conclusion, IQB without predrying can be successfully applied to
lima beans. Adjustment must be made in fill weight to arrive at the
correct drained weight since there is more rehydration in the can
with IQB blanched beans. Predrying results in a greater reduction
in effluent generation; however, predrying adversely affects product
quality due to skin splitting.
37
-------
GREEN BEAN BLANCHING
Table 15 presents a summary of the green bean blanching results.
Table 15. SUMMARY OF GREEN BEAN BLANCHING DATA3
Blanchine
treatment"
IQB-0
Deep bed
Pipe
Effluent
generation
(l./kkg)
163
125
334
BODr
(kg/kfcE)
1.0
0.55
--
Total
organic
nitrogen
(WkkK)
0.03
0.015
--
Total
phosphorus
Oca/kkK)
0.008
0.005
--
Product
yield
a)
94.0
97.3
--
Solids
lost as
product
(%)
1.16
0.89
--
Expressed per kkg of blanched product. See Tables A7 and A8 for
complete data. All pipe blanching analyses were discarded due to
inappropriate sample storage.
IQB-0 means IQB without predrying.
Deep bed means deep bed steam blanching.
Pipe means pipe blanching.
In green bean blanching, steam blanching resulted in a 51-63%
decrease in effluent generation compared to pipe blanching. With
green beans there was a different trend than with the previously
blanched products. In pea, corn or lima bean blanching the deep
bed steam blanching treatment always resulted in a greater genera-
tion of effluent. With green beans the opposite is true; that is,
deep bed blanching resulted in less effluent than IQB-0. This re-
flects the peculiar nature of green bean blanching in that the
maximum temperature reached was 79 C (175 F). In green bean blanch-
ing, the bean must reach at least 63 C (145 F) but must not exceed
82 C (180 F) in order to activate the enzyme pectin methyl esterase (PME)
This enzyme, once activated, will cleave methoxy groups from pectin
in the outer layer allowing calcium-pectin interaction and conse-
quently no sloughing. In both deep bed and IQB the mass average
temperature was between 77 C (170 F) and 82 C (180 F). Consequently
38
-------
there was no difference in the amount of steam required for heating.
Also, since there was no difference in temperature both treatments
should have resulted in equivalent surface water-holding capacity.
However, in deep bed steam blanching there was a greater water-
holding capacity in the bed itself resulting in less effluent drain-
ing from the process.
g
Rails et al'. reported effluent generation of 196 l./kkg (47 gal/ton)
for steam blanching and 7080 l./kkg (1700 gal/ton) for water blanch-
ing. Both of these values are considerably higher than the IQB-0 and
Deep Bed reported here and, in the case of steam blanching, may be
due to blanching in 100 C steam rather than a steam-air mixture at
79-82 C (175-180 F). The exceedingly high value for the water
blanching system may reflect the fact that batch-type experiments
were conducted and perhaps much more product could have been proc-
essed before the blancher water had to be changed. Also, feed and
bleed systems may be more efficient from a waste generation stand-
point than straight batch systems. Soderquist et al. reported
446 l./kkg (107 gal/ton) for a rotary steam blancher. This compares
quite favorably to the 334 l./kkg (80 gal/ton) reported here for
pipe blanching.
The BOD/N/P ratio for green bean blancher effluent was 114/3.8/1
(range 105-129/2.7-7.4/1)indicating that the liquid waste stream
probably contains adequate nitrogen and phosphorus for biological
treatment. Soderquist et al. reported a BOD/N/P ratio of 109/6/1
for the rotary blanching operation and a BOD/COD ratio of 0.53.
Predrying was not attempted in this study since results in 1971
had shown that even with a 67. weight reduction skin rupture was
severe. With predrying to less than 6%, the savings in effluent
i
39
-------
generation would not justify the cost of predrying. Therefore,
predrying prior to IQB is not recommended for green beans.
Table 16 summarizes the objective evaluations performed on green
beans. Can vacuum was noticeably lower for the two steam blanched
samples compared to pipe blanched samples. This was probably due
to brine overfill in the experimentally blanched samples since the can
vacuum values do not follow any pattern with storage time. If the
poor can vacuum had been due to presence of air cells in the green
bean tissue, the can vacuum values would have decreased upon storage.
Instead the can vacuum actually increased upon storage for the IQB
sample and fluctuated for the deep bed sample. There was no sig-
nificant difference in drained weight between any of the treatments.
For slough and percent splits, however, IQB was definitely superior
to both deep bed steam blanching and pipe blanching. These low
values are indicative that PME had been activated. With deep bed
steam blanching the surface temperature of the tissue may have been
over 180 F for short periods of time resulting in PME inactivation.
Deep bed steam blanching compares favorably to pipe blanching.
Subjective evaluation of green beans is summarized in Table 17.
From these data it is apparent that there is no real preference for
product blanched in steam or hot water. Even though the objective
tests indicated considerably less slough and percent splits for IQB,
the taste panel could not pick out that characteristic as a basis
for establishing preference. This points out the fallacy of using
only objective or subjective tests to evaluate innovative or new
processing techniques.
In conclusion, IQB and deep bed steam blanching can be used to
blanch green beans prior to canning. A steam-air mixture at 77-82 C
(170-180 F) is required to activate PME. IQB produced 51 percent
40
-------
Table 16. SUMMARY OF OBJECTIVE EVALUATION OF GREEN BEANS0
Can Vacuum
(cm. Hg. vacuum)
Blanching
treatment
IQB
Deep Bed
Pipe
IQB
Deep Bed
Pipe
IQB
Deep Bed
Pipe
IQB
Deep Bed
Pipe
Aver.
1.0
0.8
17.0
1
Range Aver .
15
0-5.1
0-1.3
.2-17.8
0.0
6.9
16.3
Months of Storage
3
Range Aver .
0-0
2.5-12.7
12.7-19.1
3.1
1.5
17.0
6
16
Range Aver .
0-7.6
0-7.6
.5-17.8
4.1
8.9
17.0
9
Range
5
16
0-8.9
.1-14.0
.5-19.1
Drained Weight
(a)
264.1
274.3
276.3
262
272
265
.8-265.2
.4-275.6
.7-282.8
266.6
275.8
241.6
260.6-272.2
273.2-279.1
240.9-242.7
270.5
275.6
287.1
266
273
283
.2-272.8
.8-276.6
.8-293.0
269.3
279.8
293.5
268
278
292
.4-270.5
.8-281.3
.9-294.2
Slough
(%)
4.0
13.5
7.8
3
12
6
.0-5.0
.0-15.0
.5-9.0
8.0
16.0
16.0
8.0-8.0
14.0-18.0
16.0-16.0
7.0
16.0
11.0
7
15
9
.0-7.0
.0-17.0
.0-13.0
10.0
15.0
15.0
9
15
14
.0-11.0
.0-15.0
.0-16.0
Splits
(%)
5.0
32.5
52.5
5
30
35
.0-5.0
.0-35.0
.0-70.0
2.5
30.0
55.0
0-5.0
25.0-35.0
50.0-60.0
5.0
35.0
22.5
5
30
20
.0-5.0
.0-40.0
.0-25.0
15.0
22.5
55.0
10
20
55
.0-20.0
.0-25.0
.0-55.0
Each average consists of at least three observations.
less effluent than pipe blanching and resulted in considerably less
slough and percent splits. Organoleptically, the steam blanched
products were quite acceptable.
41
-------
Table 17. SUMMARY OF SUBJECTIVE EVALUATION OF GREEN BEANS
Blanching
treatment3
IQB-0
Deep bed
Storage time0
(months)
1 369
0.17.
10-5-5
NS
5%
6-3-4
17.
5-6-3
NS
17.
5-8-3
57.
6-6-4
17.
5-6-6
IQB-0 means IQB without predrying.
Deep bed means deep bed steam blanching.
Each sample was compared to a pipe-blanched, canned control. The con-
trol was canned the same day as the experimental sample. The top number
is the level of significance and the bottom three numbers represent
number of judges preferring experimental sample, control and no prefer-
ence, respectively. NS means no significant difference.
POTATO BLANCHING
Potato blanching data are summarized in Table 18.
Table 18. SUMMARY OF POTATO BLANCHING DATA2
Blanching
treatment" ,
IQB-6.9
IQB-0
Deep bed
Effluent
generation
(l./kks)
100
171
167
BOD5
(kg/kkg)
0.5
0.75
0.65
Total
organic
nitrogen
(kg/kkg)
0.03
0.05
0.065
Total
phosphorus
(kg/kkg)
0.0085
0.012
0.017
Product
yield
(7.)
93.1
93.4
93.8
Solids
lost as
product
a)
0.43
0.60
0.61
Expressed per kkg of blanched product. See Tables A9 and A10 for
complete data.
IQB-6.9 means IQB with a 6.9% weight reduction prior to blanching.
IQB-0 means IQB without predrying.
Deep bed means deep bed steam blanching.
42
-------
Since potatoes are not normally blanched following slicing or dicing
there is no water blanching method to which to compare the steam
blanching method. However, these experiments were included for
those processors who both can and freeze or dehydrate potatoes.
Prior to freezing or dehydration, potatoes may be blanched. The
data for effluent generation are quite similar to those presented
for corn and reflect the water-holding capacity of the cut potato
surface. The ZODc generated per ton of product is quite low sug-
gesting that most of the free surface cellular juices were washed
off the potato prior to blanching. This prewashing was accomplished
by transporting the potatoes to the laboratory under water and then
washing them again in the pilot plant. Deep bed and IQB-0 resulted
in nearly the same effluent generation. This was due to the fact
that peroxidase inactivation in the potato slice required a heat
time of 60 seconds resulting in a mass average temperature near 93 C
(200 F). Thus, compared to deep bed steam blanching where the mass
average temperature was between 93-99 C (200-210 F), there would be
little difference in the total steam condensed. Consequently, there
was little difference between deep bed and IQB. The heat only sec-
tion of the IQB process was not run with potatoes or any of the root
crops. This was not run since it had been observed in earlier trials
that IQB-0 and the heat-only runs did not differ significantly in
effluent generation since little effluent was released in the hold
section. Also, for the root crops blanching is usually required
prior to freezing to partially cook the product. Under these cir-
cumstances the heat-only method would probably not be adequate as a
blanching technique.
The BOD/N/P ratio for potato blancher effluent was 57/3.9/1 (range
37-66/3.6-4.2/1) Indicating that adeuqate nutrients are available for
biological treatment. The BOD/COD ratio averaged 0.90.
43
-------
Objective analysis of the potato blanching trials is summarized in
Table 19. The lower can vacuum for the steam blanched samples is
attributed to overfill rather than incomplete tissue gas removal.
Table 19. SUMMARY OF OBJECTIVE EVALUATION OF POTATOES3
Blanching,
treatment
IQB-6.9
IQB
Deep Bed
Control
IQB-6.9
IQB
Deep Bed
Control
Can Vacuum
(cm. Hg. vacuum)
Aver.
12.2
12.4
9.4
22.4
334.6
343.6
345.1
312.4
1
Range Aver.
8.9-16.5
10
3
16
332
335
334
285
.2-19.1
.8-11.4
.5-27.9
7.9
7.8
8.6
17.3
.2-335.0
.0-352.9
.4-352.8
.7-335.4
330.6
330.9
244.9
286.6
Months of Storage
3
Range Aver.
5.1-10.2
5.1-11.4
6.4-12.7
14.0-25.4
10.9
12.7
11.7
18.5
Drained Weight
(g)
326.1-333.8
320.7-335.7
328.4-356.2
274.2-301.3
338.2
336.3
340.5
311.3
6
Range Aver .
7.6-15.2
7
10
12
331
328
328
292
.6-17.8
.2-17.8
.7-24.1
12.2
10.9
16.0
20.6
.4-342.9
.8-340.4
.3-358.1
.6-350.8
333.1
336.0
337.4
308.4
9
8
7
14
15
328
325
330
283
Elange
.9-16.5
.6-15.2
.0-19.1
.2-25.4
.6-336.8
.3-343.9
.4-343.7
.1-357.1
Each average consists of at least three observations.
Control samples were not blanched prior to canning. The whole potato was treated
in hot water and steam before peeling.
The higher drained weights for the steam blanched samples show an over-
fill of about 28 g. (one ounce). Thus, instead of filling at a 312 g.
(11 ounce) fill weight, a 284 g. (10 ounce) fill weight would be suf-
ficient.
Table 20 presents a summary of the subjective evaluations on potatoes.
The IQB predried blanching technique was not acceptable due to darkening
of the potato surface during air drying. This is evidenced by the low
preference for the IQB-predried sample. With IQB and deep bed steam
44
-------
Table 20. SUMMARY OF SUBJECTIVE EVALUATION OF POTATOES
Blanching
treatment3
IQB-6.9
IQB-0
Deep bed
Storage time15
(months)
1369
5%
2-9-3
NS
0.1%
4-9-3
0.1%
4-6-8
NS
NS
1%
5-5-6
NS
NS
NS
1%
4-8-5
1%
8-5-2
IQB-6.9 means IQB with a 6.9% weight reduction prior to blanching.
IQB-0 means IQB without predrying.
Deep bed means deep bed steam blanching.
Each sample was compared to a control sample. The control was canned
the same day as the experimental sample. The top number is the level
of significance and the bottom three numbers represent number of judges
preferring experimental sample, control and no preference, respectively.
NS means no significant difference.
blanching there was very little difference in samples as evidenced
by the taste panel results. However, when the products were com-
pared in large quantity batches (for example, a can full), the steam
blanched product appeared somewhat darker than the pipe blanched.
This was believed due to darkening of the potatoes in transport to
the laboratory. The importance of this slight darkening is not
readily apparent since the taste panel showed no preference.
In conclusion, IQB without predrying can be successfully applied to
potato blanching. At the loading rates used in this study, IQB
offered little advantage over deep bed steam blanching. However,
at greater loading rates IQB would fee expected to produce sig-
nificantly less effluent than deep bed steam blanching. The IQB
blanched product was equivalent to conventionally canned product.
Predrying is not recommended due to surface darkening during air
dehydration.
45
-------
BEET BLANCHING
The beet blanching data are summarized in Table 21,
Table 21. SUMMARY OF BEET BLANCHING DATA*1
Blanching
treatment**
IQB-5.6
IQB-0
Deep bed
Effluent
generation
a./kkit)
196
229
225
BODs
(kg/kkO
5.75
4.95
4.8
Total
organic
nitrogen
(kg/kkg)
0.11
0.085
0.11
Total
phosphorus
(kg/kkg)
0.0285
0.022
0.0305
Product
yield
(%)
86.3
89.4
88.9
Solids
lost as
product
(%)
5.21
4.02
5.26
Expressed per kkg of blanched product. See Tables All and A12 for
complete data.
IQB-5.6 means IQB with a 5.6% weight reduction prior to blanching.
IQB-0 means IQB without predrying.
Deep bed means deep bed steam blanching.
As with potatoes sliced beets are not normally blanched prior to
canning and, therefore, there is no conventional blanching operation
for comparison. Generally it is assumed that blanching will be
accomplished in the steam treatment and/or hot water process just
prior to peeling. Frequently, however, the center temperature of
the beet is not in the range to inactivate enzymes. When this is
the case, delay in getting the sliced or diced beets in the can may
result in darkening of the beet. This is undesirable. The beet
slices that were obtained from the canning plant for this study had
positive peroxidase activity prior to the steam blanching runs.
The data in Table 21 reveal several important characteristics of
beet blanching. First, the effluent generation values are nearly
the same as those reported for pea blanching. The high effluent
generation values, however, are the result of cellular losses rather
46
-------
than inability of-the beet surface to hold surface moisture. The
BOD values are the highest of those reported in this study as are
the "solids lost as product" figures. This indicates that beet
tissue is very susceptible to heat damage. Consequently, any method
of blanching will result in high solids loss from the tissue. For
0
comparison, Rails et al. reported 317 l./kg (76 gal/ton) for steam
blanching of beets and 5550 l./kkg (1330 gal/ton) for water blanch-
ing. Comparing IQB to those results, IQB would reduce liquid waste genera-
tion by about 28%. As with green beans, the 5550 l./kkg (1330 gal/
ton) is probably unduly large since presumably more product could
have been run through the blancher, lowering the effluent value.
Fredrying the beet surface prior to IQB resulted in a further de-
crease in effluent generation; however, during air drying some
darkening did occur. This was undesirable and resulted in a low
preference for that treatment.
The BOD/N/P ratio averaged 208/3.8/1 (range 158-292/3.6-4.0/1) indi-
cating that beet blancher water maybe low in nitrogen for biological
waste treatment. The BOD/COD ratio averaged 0.97 slightly higher
than the 0.87 reported by Soderquist et al.
Objective evaluation of beets resulted in the data summarized in
Table 22. The can vacuum was lower for all the steam blanched
samples compared to control. Examination of the drained weight
data shows that the experimental samples contained at least 56 g.
(two ounces) more than the control and were overfilled. Instead of
using the 312 g. (11 ounce) fill weight, the fill weight could have
been 256 g. (9 ounces). The drained weight data show that in the
can the beet will lose tissue juices during the-retorting operation
and consequently the drained weight is less than the fill weight.
By blanching prior to canning the juice is lost before the beet is
put in the can. From a canner's point of view it is best not to
47
-------
blanch prior to canning since then he has to clean up the blancher
effluent. Without blanching, the effluent ends up in the can and
eventually ends up in the kitchen where the housewife disposes of
it. On the other hand, if the canner has difficulty making drained
weight on canned beets, then blanching prior to canning will allow
him to more nearly match fill weight to drain weight.
Table 22. SUMMARY OF OBJECTIVE EVALUATION OF BEETS3
Blanching
treatment*
IQB-5.6
IQB
Deep Bed
Control
IQB-5.6
IQB
Deep Bed
Control
Can Vacuum
(cm. Hg. vacuum)
Aver.
10.4
11.9
10.4
22.9
330.3
327.5
326.3
265.5
1
8
7
6
16
327
323
323
249
Range Aver .
.9-11.4
.6-15.2
.4-12.7
.5-33.0
7.9
6.4
5.1
16.3
.2-331.4
.4-332.3
.8-327.0
.7-281.0
329.7
325.7
329.2
262.1
Months of Storage
3
Range Aver.
5.1-15.2
5.1-7.6
5.1-5.1
10.2-22.9
8.6
4.6
6.1
15.0
Drained Weight
(g)
326.6-330.8
320.3-328.2
320.8-332.7
240.5-279.0
329.2
332.3
336.3
250.2
6
5
2
2
11
327
328
328
218
Range Aver.
.1-10.2
.5-5.1
.5-10.2
.4-19.1
5.8
7.6
12.4
16.8
.6-330.8
.3-338.0
.3-340.0
.0-266.5
332.8
329.4
332.8
259.6
9
5
5
7
10
329
323
325
244
Range
.1-8.9
.1-10.2
.6-15.2
.2-20.3
.8-334.9
.1-337.8
.1-339.1
.1-288.5
Each average consists of at least three observations
Control samples were not blanched prior to canning. The whole beet was treated
in hot water and steam before peeling.
Table 23 presents a summary of the subjective evaluations of beets.
The predried beets were definitely of poorer quality than the con-
trol, the primary difference being the darker color of the predried
samples. For the other steam blanching methods no consistent dif-
ference was found.
48
-------
Table 23. SUMMARY OF SUBJECTIVE EVALUATION OF BEETS
Blanching
treatment3
IQB-5.6
IQB
Deep bed
1
1%
4-7-4
NS
1%
6-6-4
Storage timeb
(months)
3,6 9
NS
NS
NS
1%
3-7-4
NS
0.17.
2-15-1
0.1%
4-7-11
NS
NS
IQB-5.6 means IQB with a 5.6% weight reduction prior to blanching.
IQB-0 means IQB without predrying.
Deep bed means deep bed steam blanching.
Each sample was compared to a control sample. The control was canned
the same day as the experimental sample. The top number is the level of
significance and the bottom three numbers represent number of judges
preferring experimental sample, control and no preference, respectively.
NS means no significant difference.
In conclusion, IQB without predrying is an effective way of blanch-
ing beets with reduced effluent generation. Beet tissue is extremely
sensitive to high temperatures resulting in loss of tissue juice.
Predrying reduces effluent further; however, product quality is ad-
versely affected. Blanching prior to canning would be an effective
way to insure meeting drained weights for beets.
CARROTS
Carrot blanching data are summarized in Table 24. Carrots, like
other root crops, beets and potatoes, are not normally blanched
after slicing or dicing unless they are to be frozen or dehydrated.
Therefore, there was no commercial blanching operation to monitor
in this study. Even though the whole carrot receives a hot water
and steam treatment prior to peeling, peroxidase activity was still
present in the sliced carrots. The values in Table 24 for effluent
49
-------
Table 24. SUMMARY OF CARROT BLANCHING DATA'
Blanching
treatment13
IQB-0
Deep bed
Effluent
generation
(l./kkg)
192
225
BOD5
(kg/kkg)
2.0
2.6
Total
organic
nitrogen
(kg/kkg)
0.10
0.14
Total
phosphorus
(kg/kkg)
0.016
0.023
Product
yield
a)
91.8
88.4
Solids
lost as
product
a)
1.93
2.77
Expressed per kkg of blanched product. See Tables A13 and A14 for
complete data.
IQB-0 means IQB without predrying.
Deep bed means deep bed steam blanching.
generated are similar to the others reported in this study. Pre-
drying would be expected to reduce blancher effluent even further.
3
In the original studies by Lazar et al. carrots predried to a
5.8% weight reduction produced only half as much effluent as IQB
without predrying. The product yield values reported here indi-
cated that the carrot surface loses some of its moisture-holding
capacity as the surface temperature is increased since the losses
are in excess of those calculated from solids loss. The BOD/N/P
ratio averaged 122/6.3/1 (range 117-126/6.1-6.7/1) indicating that
carrot blancher effluent has adequate nutrients for
biological waste treatment. The BOD/COD ratio was 0.87.
Table 25 presents the results on the objective evaluation of
carrots. There was no significant difference in either the can
vacuum or drained weights when steam blanched samples were compared
to control samples.
Subjective evaluation results for carrots are shown in Table 26.
The preference of the taste panel for the control sample is markedly
evident in these data. This serves to illustrate the importance of
50
-------
Table 25. SUMMARY OF OBJECTIVE EVALUATION OF CARROTS
Can Vacuum
(cm. Hg. vacuum)
Blanching,
treatment
IQB
Deep bed
Control
IQB
Deep bed
Control
Aver.
9.1
11.7
9.1
1
7
8
7
Months of Storage
3
Range Aver. Range Aver.
.6-11.4
.9-15.2
.6-11.4
7.9
10.9
7.1
7.6-8.9
7.6-12.7
3.8-8.9
9.9
8.1
7.9
6
5
2
2
Range Aver.
.1-16.5
.5-15.2
.5-12.7
13.7
14.0
10.9
9
12
12
10
Range
.7-15.2
.7-15.2
.2-12.7
Drained Weight
(g) f
284.0
293.9
267.5
280
291
259
.1-285.5
.1-295.4
.4-274.7
286.6
292.5
265.5
284.0-288.8
290.7-293.4
262.5-277.7
284.3
290.5
280.6
281
285
272
.4-287.9
.9-293.2
.4-292.2
283.1
293.7
278.3
278
291
273
.1-286.6
.5-295.2
.0-284.8
Each average consisted of three observations.
Control samples were not blanched prior to canning. The whole carrot was treated in
hot water and steam before peeling.
Table 26. SUMMARY OF SUBJECTIVE EVALUATION OF CARROTS
Blanching
treatment3
1 3
Storage time"
(months)
6
9
IQB
Deep bed
0.1%
0-11-5
0.1%
2-11-7
0.1%
6-13-7
0.1%
5-10-6
0.1%
5-12-3
0.1%
4-11-5
0.1%
1-9-10
0.1%
2-8-10
IQB means IQB without predrying.
.Deep bed means deep bed steam blanching.
Each sample was compared to a control sample. The control was canned
the same day as the experimental sample. The top number is the level of
significance and the bottom three numbers represent number of judges
preferring experimental sample, control and no preference, respectively.
51
-------
color in product evaluation. The steam blanched carrots were trans-
ported to the laboratory and there was considerable darkening of the
tissue even though it was held under water. The taste panel preferred
the brighter orange color of the control. In the study by Lazar et
3
al. IQB samples were judged to be better than the conventionally
steam blanched product. In the opinion of most of the judges the only
difference between samples in the present study was color.
In conclusion, IQB can be used to blanch carrots prior to canning,
freezing or dehydration. There was no adverse effects of the steam
blanching treatment on carrots prior to canning. Blanching of carrots
prior to canning could be recommended if there are unduly long delays
between cutting and can filling. During this delay color changes
could occur.
LOADING RATE AND SIZE OF COMMERCIAL IQB UNITS
One of the basic principles inherent in-IQB is that each piece of
vegetable receives the same thermal energy as every other piece. If
there is some condition which alters exposure time or rate of heat
transfer to the surface of the vegetable, then there is the possi-
bility of underblanching. In heat transfer the total quantity of
heat transferred is directly proportional to the exposed surface
area. Loading conditions which will decrease total surface exposed
may result in underprocessing and therefore belt loading rate is an
extremely important variable in the IQB process.
The belt loading rates for the heat belt, hold belt and deep bed
steam heating belt were calculated based on through-put, residence
time and belt dimensions. The results for each run are given in
the Appendix.
52
-------
To summarize the data, the following observations can be made: 1)
Heat belt loading--for the IQB process the heat belt was loaded at
2 2
approximately 4.9 kg/m (1 Ib./ft ). ' For these products this would
be optimal loading for exposing each piece to the steam conditions
in the heat section. This loading was recommended in previous publi-
o
cations on IQB . For beets and carrots, belt loadings were some-
what higher, generally 6.3 to 9.8 kg/m2 (1.3 to 2.0 Ib./ft ). With
these two products higher product loading rates could be used since
medium slices (3.2-4.4 cm. diameter by 0.64 cm. thick) did not pack
and reduce heat transfer surface area as much as other product forms
(i.e. peas, corn, lima beans, or green beans). With deep bed blanch-
ing, loading rate was limited by configuration of the equipment. The
deep bed was 5.1 to 6.4 cm. (2 to 2.5 inches) deep resulting in dif-
2
ferent loading rates depending on product geometry: peas--12.9 kg/m
(2.65 lb/ft2); corn--14.5 kg/m2 (2.98 lb/ft2); lima beans14.8 kg/m2
(3.04 lb/ft2); green beans7.03 kg/m2 (1.44 lb/ft2); potatoes
11.8 kg/m2 (2.41 lb/ft2); beets16.4 kg/m2 (3.36 lb/ft2) and carrots
2 2
16.0 kg/m (3.28 lb/ft ). Green beans had the lowest product density
in the deep bed. This would be expected since cylinders with a
length to diameter ratio of 3:1 have a very low packing density. 2)
Hold belt loadings in the IQB process hold belt loadings varied
from 17.6 kg/m2 (3.6 lb/ft2) for potatoes to 69.3 kg/m2 (14.2 lb/ft2)
for green beans. Hold section belt loading reflects the compounding
effect of many variables including ratio of heat residence time to
hold residence time, ratio of heat belt width to hold belt width,
and ratio of heat section length to hold section length. For our
system the heat and hold belts were nearly the same width [21.6 cm
(8.5 inch) wide heat belt; 20.3 cm (8.0 inch) wide hold belt] and
the length ratio was 3/1 [i.e. 91.4 cm (3 ft) heat section/30.5 cm
(1 ft) hold section]. The ratio of heat belt loading to hold belt
loading should, under these conditions, be equal to the ratio of the
lineal velocity of the hold belt to the lineal velocity of the heat
belt.
53
-------
loading rate heat belt\ _ | lineal velocity hold belt
loading rate hold belt I 1 lineal velocity heat belt
The lineal velocity is the length of the belt divided by the resi-
dence time in the section and since L(Heat)/L(Hold) = 3/1, the load-
ing rate on the heat belt/loading rate on the hold belt is:
_ Heat / 1 \ residence time in heat section
(Loading rate)u . . I 3 / residence time in hold section
Ho la
or
(L-R')Heat Heat
(L'R')Hold 3 r Hold
where L.R. - loading rate, kg/m2
and ? - residence time, seconds.
Using heat/hold times reported in this study, the size of a commer-
cial belt-type IQB unit was calculated and is given in Table 27. A
2 2
heat belt loading rate of 4.9 kg/m (1 Ib/ft ) and a hold belt
2 2
loading rate of 49 kg/m (10 Ib/ft ) was assumed. Blanch times are
the same as those reported in Table 3. For commercial units it
would be expected that costs for an IQB blancher of this configura-
tion would not be more than that for rotary-type water blanchers of
comparable production capacity. Compared to conventional steam
blanchers, IQB would be less costly since the IQB unit is consider-
ably shorter for the same production capacity.
Regarding developments of hardware for IQB units, the engineering
research team at Western Regional Research Laboratory, USDA,
Berkeley, recently reported on the development of a prototype
IQB unit using spiral vibrating conveyors. High production rates,
compactness, simplicity and control of residence time were claimed
54
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for the unit. A larger prototype is planned for construction.
Table 27. ESTIMATED IQB PRODUCTION UNITS
a
Product
Peas
Corn
Lima beans
Green beans
Potatoes
Carrots
Beets
Production rate
(kkg product/hr) (tons product/hr)
9.1
13.6
13.6
13.6
4.5
5.7
5.7
10
15
15
15
5
6.3
6.3
a
Heatl.52in(5 ft) wide x 9.14 m (30 ft) long loaded at
4.9 kg/m2 (1 lb/ft2).
Hold 1.52 m (5 ft) wide x 1.37 m (4.5 ft) long loaded at
49 kg/m2 (10 lb/ft2).
55
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SECTION VII
UNITS FOR INTERCONVERSION OF DATA
To aid in the interconversion and increased digestibility of data con-
tained in this report, several important conversion factors are pre-
sented in the following table:
Table 28. FACTORS FOR INTERCONVERSION OF DATA
To convert from:
cm
g
kkg
kg/m2
cm
l./kkg
kg/kkg
l./hr
l./case
To:
ft.
ounces
ton
lb/ft2
in.
gal /ton
Ib/ton
gal/hr
gal/case
Multiply by:
0.0328
0.0353
1.103
0.205
0.394
0.240
2.00
0.264
0.264
All of the values contained in this report based on the amount of
product were calculated based on the amount of product (kkg or ton)
processed. It is frequently desirable to know effluent generation
based on plant input rather than plant output. Therefore, to facili-
tate these calculations the following are given:
56
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Table 29. CANNING YIELD FACTORS
Pounds product Cases
Product
Peas
Corn
Lima beans
Green beans
Potatoes
Beets
Carrots
case
15.5
15.75
13.5
13.5
16.5
16.5
14.6
ton raw product
115
32
130
125
75
70
65
Ton raw product
ton processed product
1.13
3.97
1.14
1.19
1.62
1.73
2.10
o
Calculated based on fill weight.
b
Reference 12.
57
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SECTION VIII
REFERENCES
1. Weckel, K. G., R. S. Rambo, H. Veloso, and J. H. von Elbe. Vegetable
Canning Process Wastes. Res. Rpt. No. 38. College of Agricultural
and Life Sciences, Univ. Wisconsin-Madison, p. 1-20, 1968.
2. National Canners Association. Res. Information Bull. No. 170,
January 1971.
3. Lazar, M. E., D. B. Lund and W. C. Dietrich. IQB: A New Concept in
Blanching. Food Tech. 25:684-686, July 1971.
4. Lund, D. B., S. L. Bruin, Jr., and M. E. Lazar. Internal Temperature
Distribution During Individual Quick Blanch. J. Food Sci. 37:183,
January 1972.
5. Lund, D. B. A Field Study on the Application of Individual Quick
Blanch. In: Proceedings Third National Symposium on Food Processing
Wastes. Washington, D. C., U. S. Government Printing Office. EPA-
R2-72-018, 1972.
6. Standard Methods for the Examination of Water and Waste Water. 13th
ed. New York, Amer. Publ. Health Assoc., Inc., 1790 Broadway, 1971.
7. Van Buren, J. P., J. C. Moyer, D. E. Wilson, W. C. Robinson, and
D. B. Hand. Influence of Blanching Conditions on Sloughing, Splitting
and Firmness of Canned Snap Beans. Food Tech. 14:233, 1960.
8. Rails, J. W., H. J. Maagdenberg, N. L. Yacoub, and W. A. Mercer.
Reduced Waste Generation by Alternate Vegetable Blanching Systems.
In: Proceedings Third National Symposium on Food Processing Wastes.
Washington, D. C., U. S. Government Printing Office. EPA-R2-72-018,
1972. p. 25-70.
58
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REFERENCES (continued)
9. Lee, F. A. The Blanching Process. In: Advances in Food Research.
Vol. 8. New York, Academic Press., 1958. p. 63.
10. Soderquist, M. R., G. I. Blanton and D. W. Taylor. Characterization
of Fruit and Vegetable Processing Waste Waters. In: Proceedings
Third National Symposium on Food Processing Wastes. Washington,
D. C., U. S. Government Printing Office. EPA-R2-72-018, 1972.
p. 409-436.
11. Brown, G. E. Personal Communication and paper presented at the
Annual Meeting Institute of Food Technologists, Miami Beach,
June 1973.
12. . 1971-1972 Yearbook. Canner Packer. 140:9, 1971. p. 102.
59
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SECTION IX
LIST OF PUBLICATIONS
Lund, D. B. The Individual Quick Blanching Process. Michigan State
University. Highlights in Food Science, March 1973.
Lund, D. B. Impact of the Individual Quick Blanch (IQB) Process on
Cannery Waste Generation. Presented at the Fourth National Sym-
posium on Food Processing Wastes, Syracuse, New York, April 1973.
Lenz, M. K. and D. B. Lund. Lethality Calculations for Heat/Cool
Processes by the L-Fo Method. Submitted to J. Food Science, 1973.
60
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Section X
Appendix - Raw Data
Page
Al Individual Blanching Trials for Peas 62
A2 Characteristics of Effluents Generated During Pea 63
Blanching
A3 Individual Blanching Trials for Corn 65
A4 Characteristics of Effluents Generated During 66
Corn Blanching
A5 Individual Blanching Trials for Lima Beans 68
A6 Characteristics of Effluents Generated During 69
Lima Bean Blanching
A7 Individual Blanching Trials for Green Beans 71
A8 Characteristics of Effluents Generated During 72
Green Bean Blanching
A9 Individual Blanching Trials for Potatoes 73
A10 Characteristics of Effluents Generated During 74
Potato Blanching
All Individual Blanching Trials for Beets 75
A12 Characteristics of Effluents Generated During 76
Beet Blanching
A13 Individual Blanching Trials for Carrots 77
A14 Characteristics of Effluents Generated During 78
Carrot Blanching
61
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Table Al. INDIVIDUAL BLANCHING TRIALS FOR PEAS
^
Blanching
treatment
IQB-6.25-4-A1S
lQB-O-4-Als
30 Sec-4-Als
Deep bed-4-Als
IQB-7.0-3-Ala
lQB-O-3-Ala
30 Sec-3-Ala
Deep bed-3-Ala
IQB-7.5-Perf.
lQB-0-Perf.
30 Sec- Per f .
Deep bed- Per f.
Averages
IQB-6.9
IQB-0
30 Sec
Deep bed
Treat-
ment
number
IP
2P
3P
4P
5P
6P
7P
8P
9P
10P
IIP
12P
Belt loading
Heat
(kg/m2)
5.08
5.42
5.42
13.13
4.49
4.39
4.20
13.52
5.42
5.86
5.22
12.20
5.00
5.22
4.93
12.93
Hold
(kg/m2)
24.20
25.82
21.52
20.94
25.91
28.01
23.86
24.94
Effluent
generation
(l./case)
1.09
1.76
1.51
2.15
0.913
1.47
1.39
2.15
1.10
1.51
1.51
2.29
1.04
1.58
1.47
2.19
Product
yield
(%)
88.8
87.5
90.0
83.8
90.0
90.5
91.3
83.8
87.5
90.0
90.0
82.5
88.8
89.3
90.4
83.3
Solids lost
as product
(%)
1.37
1.57
2.10
3.31
1.14
2.51
1.85
2.77
2.10
2.12
2.33
3.26
1.53
2.07
2.09
3.11
IQB-6.25 means IQB with a 6.25% weight reduction prior to blanching.
IQB-0 means IQB without predrying.
30 sec means heat only stage of IQB.
Deep bed means deep bed steam blanching.
4 or 3 refers to sieve size; perfection was sieve size 3, 4 and 5.
Als means Alsweet; Ala means Alaskan; Perf. means Perfection.
62
-------
Table A2. CHARACTERISTICS OF EFFLUENTS GENERATED DURING PEA BLANCHING
a
Treatment
number
IP
2P
3P
4P
5P
6P
7P
8P
9P
10P
IIP
12P
Pipe
Pipe
Averages
IQB-6.9
IQB-O
30 Sec
Deep bed
Pipe
BOD5
(ppnu
9730
7260
11300
13200
10300
15800
10500
13400
15600
11400
13600
14200
8300
7500
11900
11500
11800
13600
7900
Total
solids
00
1.99
1.43
2.16
2.58
1.94
2.66
2.04
2.16
3.06
2.18
2.40
2.44
1.54
1.42
2.33
2.09
2.20
2.39
1.48
Total
phosphorus
(ppm)
82
77
107
113
164
215
167
174
195
154
162
189
150
105
147
149
145
159
128
Total organic
nitrogen
(ppm)
414
294
485
596
548
768
612
678
893
684
747
824
463
433
618
582
615
699
448
63
-------
Table A2 (continued). CHARACTERISTICS OF
EFFLUENTS GENERATED DURING PEA BLANCHING
Treatment
number
IP
2P
3P
4P
5P
6P
7P
8P
9P
10P
IIP
12P
Pipe
Pipe
Averages
IQB-6.9
IQB-0
30 Sec
Deep bed
Pipe
Volatile
solids
(ppm)
18000
13000
19600
23500
17300
23400
18200
19200
27100
19200
21200
21600
13400
12200
20800
18500
19700
21400
12800
Suspended
volatile
solids
(ppm)
644
476
595
581
329
547
473
389
2170
1120
1230
991
200
775
1050
713
765
654
488
Suspended
solids
(%)
.066
.055
.069
.070
.034
.058
.052
.050
.224
.119
.132
.108
.025
.087
.108
.077
.084
.076
.056
Soluble
phosphorus
(ppm)
37
30
46
55
75
113
102
99
101
1 84
94
91
77
52
71
76
81
82
65
Nitrogen
NH3
(ppm)
20
15
19
27
24
28
16
22
37
32
32
37
25
36
27
25
23
29
31
NO
NO 2
(ppm)
1.0
0.7
0.6
0.6
0.9
0.8
0.6
0.6
0.6
0.7
0.6
1.0
0.6
0.9
0.8
0.7
0.6
0.7
0.8
N02b
(ppm)
~
M w
^ ^
.16
.08
.05
.05
M V
.09
.16
.08
.05
.05
.09
pH
7.0
7.0
7.0
7.0
6.6
6.9
6.9
6.9
6.8
7.0
6.9
6.9
7.7
7.3
6.8
7.0
6.9
6.9
7.5
See footnote and treatment number on Table Al.
blanching.
Pipe means pipe
No value indicates too small to be measured.
64
-------
Table A3. INDIVIDUAL BLANCHING TRIALS FOR CORN
Blanching
treatment
IQB-7.5
IQB-0
20 Sec
Deep bed
IQB-7.5
IQB-0
20 Sec
Deep bed
IQB-7.5
IQB-0
20 Sec
Deep bed
Averages
IQB-7.5
IQB-0
20 Sec
Deep bed
Treatment
number
1C
2C
3C
4C
5C
6C
7C
8C
9C
IOC
11C
12C
Belt loading
Heat
(kg/n3
4.73
4.39
4.39
12.40
5.66
3.81
4.39
16.40
6.30
5.12
5.12
14.84
5.56
4.44
4.64
14.54
Hold
(kg/m2)
22.59
20.94
--
27.08
18.30
30.11
24.40
26.60
21.23
Effluent
generation
(l./case)
.489
.978
.822
1.17
.644
.921
1.00
1.20
.728
.819
.826
1.11
6.22
.906
.883
1.16
Product
yield
(°/\
\ i°)
94.7
96.3
98.1
94.1
92.8
96.9
95.9
93.8
91.9
98.1
98.1
94.9
93.1
97.1
97.4
94.2
Solids lost
as product
a)
.50
1.43
1.00
1.90
1.14
1.75
1.87
3.19
.79
1.66
1.68
2.17
.81
1.61
1.52
2.42
IQB-7.5 means IQB with 7.5% weight reduction prior to blanching.
IQB-0 means IQB without predrying.
20 sec means heat only stage of IQB.
Deep bed means deep bed steam blanching.
65
-------
Table A4. CHARACTERISTICS OF EFFLUENTS GENERATED DURING CORN BLANCHING
a
Treatment
number
1C
2C
3C
4C
5C
6C
7C
8C
9C
IOC
11C
12C
Pipe
Pipe
Pipe
Averages
IQB-7.5
IQB-0
20 Sec
Deep bed
Pipe
BODr
(ppm)
10400
14000
12500
16600
24900
22700
28300
37800
13800
26500
31000
26800
3000
6500
11000
16400
21000
23900
27000
6800
COD
(ppm)
--
29900
32400
33400
51900
23300
34200
34500
30700
--
26600
33300
34000
41300
Total
solids
(%)
1.94
2.71
2.23
3.10
3.38
3.50
3.48
5.09
2.13
3.68
3.72
3.69
.455
.884
1.61
2.48
3.30
3.14
3.96
.983
Total
phosphorus
(ppm)
104
159
135
170
105
132
142
189
87
172
169
154
30
40
72
99
154
149
171
47
Total
organic
nitrogen
(ppm)
177
296
231
260
211
255
256
322
196
368
398
318
68
100
208
195
306
295
300
125
66
-------
Table A4 (continued). CHARACTERISTICS OF
EFFLUENTS GENERATED DURING CORN BLANCHING
Volatile
Treatment solids
number (ppm)
1C 18300
2C 25600
3C 20900
4C 29100
5C 32400
6C 33500
7C 33300
8C 48900
9C 20500
IOC 35300
11C 35900
12C 34200
Pipe 3970
Pipe 8250
Pipe 15200
Averages
IQB-7.5 23700
IQB-0 31500
20 Sec 30000
Deep bed 37400
Pipe 9140
Suspended
volatile
solids
(ppm)
1240
1700
3010
712
1780
6390
8660
2460
1360
13400
4710
2060
215
460
1120
1460
7170
5460
1750
600
Suspended
solids
(%)
.136
.179
.307
.076
.187
.639
.880
.247
.136
(1.344)C
.471
.206
.022
.047
.112
.153
.409°
.553
.176
.060
Soluble
phosphorus
(ppm)
50
89
86
98
101
106
114
151
17
38
37
24
15
30
18
56
78
79
91
21
Nitrogen
NH3
Cppm)
7
5
4
8
22
13
13
25
11
14
13
16
2
7
7
13
11
10
17
5
NO b
NO^
(ppm)
N02d
(ppm)
--
.02
.03
.03
Trace
Inter
Inter
Inter
Inter
.10
Inter
.02
.03
.03
Trace
.10
pH
6.5
6.4
6.8
6.8
7.0
7.0
6.9
6.9
7.0
6.9
7.0
7.2
7.5
7.9
6.9
6.8
6.8
6.9
7.0
7.4
See footnote and treatment number on Table A3.
Interference on all Npg-N determinations.
The 1.344 value was not used in the average since it was higher than
corresponding values by factor of 10.
No value means too small to be measured.
Inter means interference.
67
-------
Table A5. INDIVIDUAL BLANCHING TRIALS FOR LIMA BEANS
a
Blanching
treatment
IQB-5.0
IQB-O
20 Sec
Deep bed
IQB-O
20 Sec
Deep bed
Averages
IQB-5
IQB-O
20 Sec
Deep bed
treatment
number
1LB
2LB
3LB
4LB
5LB
6LB
7LB
Belt loading
Heat
Hcg/m2)
4.83
5.76
6.10
15.32
4.39
5.12
14.35
4.83
5.08
5.61
14.84
Hold
(kg/m2)
61.78
73.15
55.79
61.78
64.46
Effluent
generation
(l./case)
.406
.879
.750
1.00
1.22
.860
1.91
.406
1.05
.807
1.46
Product
yield
(%)
97.5
95.6
97.5
94.1
91.3
95.9
83.4
97.5
93.4
96.7
88.7
Solids lost
as product
(%)
.24
.63
.34
.84
1.10
.75
1.93
.24
.86
.54
1.38
IQB-5.0 means IQB with a 5.0% weight reduction prior to blanching.
IQB-O means IQB without predrying.
20 sec means heat only stage of IQB.
Deep bed means deep bed steam blanching.
68
-------
Table A6. CHARACTERISTICS OF EFFLUENTS GENERATED
DURING LIMA BEAN BLANCHING
o
Treatment
number
1LB
2LB
3LB
4LB
5LB
6LB
7LB
Pipe
Pipe
Pipe
Pipe
Averages
IQB-5.0
IQB-O
20 Sec
Deep bed
Pipe
BOD5
(ppm)
5220
6170
5810
12800
13700
29900
16300
1200
770
400
400
5220
9930
17800
14500
693
COD
(ppm)
7790
11900
6750
13800
17600
12800
21200
7790
14800
9780
17500
Total
solids
(°/\
\lo)
1.20
1.48
0.91
1.77
1.96
1.80
2.42
.20
- .13
.10
.10
1.20
1.72
1.36
2.10
.13
Total
phosphorus
(ppm)
53
71
47
100
160
146
225
38
8
6
6
53
116
97
163
15
Total
organic
nitrogen
(ppm)
341
557
318
495
864
560
879
42
26
27
28
341
711
439
687
31
69
-------
Table A6 (continued). CHARACTERISTICS OF
EFFLUENTS GENERATED DURING LIMA BEAN BLANCHING
Volatile
Treatment solids
number (ppm)
1LB 9830
2LB 12300
3LB 7470
4LB 14500
5LB 14100
6LB 15200
7LB 19600
Pipe 1390
Pipe 850
Pipe 625
Pipe 660
Averages
IQB-5.0 9830
IQB-0 13200
20 Sec 11400
Deep bed 17000
Pipe 881
Suspended
volatile
solids
(ppm)
606
2320
1370
2250
2520
1660
2650
125
65
25
30
606
2420
1520
2450
61
Suspended
solids
(%)
.060
.240
.154
.228
.263
.182
.282
.014
.010
.004
.005
.060
.252
.168
.255
.008
Soluble
phosphorus
(ppm)
35
40
27
43
9
8
10
13
2
1
1
35
25
18
26
4
Nitrogen
NH3
(ppm)
6
9
7
16
20
17
13
2
1
2
1
6
15
12
14
2
NO &
NOj
(ppm)
4.5
4.1
3.2
3.1
Inter
Inter
Inter
2.7
2.5
Inter
Inter
4.5
4.1
3.2
3.1
2.6
b
N02
(ppm)
.07
.05
.05
.02
Inter
Inter
Inter
.02
.02
Inter
Inter
.07
.05
.05
.02
.02
PH
6.8
6.7
6.8
6.4
6.5
6.6
6.5
8.5
8.6
7.9
7.6
6.8
6.6
6.7
6.5
8.2
See footnote and treatment number on Table A5.
Pipe refers to pipe blanching.
Inter means interference.
70
-------
Table A7. INDIVIDUAL BLANCHING TRIALS FOR GREEN BEANS
Blanching
treatment
IQB-0
Deep bed
IQB-O.
IQB-C
Deep bed
Deep bed
Averages
IQB-0
Deep bed
Preatment
number
1GB
2GB
3GB
4GB
5GB
6GB
Belt loading
Heat
(kg/m2
6.78
7.42
4.39
5.12
6.73
6.88
5.42
7.03
Hold
(kg/m2)
86.72
55.78
65.05
69.20
Effluent
generation
(l./case)
1«30
1.10
.841
.883
.618
.603
1.01
.773
Product
yield
a)
90.0
92.8
96.3
95.6
99.4
99.7
94.0
97.3
Solids lost
as product
(%)
w w
2.09
1.88
.45
.34
.23
1.16
.89
IQB-0 means IQB without predrying.
Deep bed means deep bed steam blanching.
71
-------
Table A8. CHARACTERISTICS OF EFFLUENTS GENERATED
DURING GREEN BEAN BLANCHING
a
Treatment
number
1GB
2GB
3GB
4GB
5GB
6GB
Averages
IQB-0
Deep bed
BOD
(ppm}
5890
9320
10100
2230
2560
1790
6070
4560
COD
(ppm)
2910
6530
--
--
--
__
2910
6530
Total
solids
(%)
--
1.26
1.43
.324
.341
.235
.877
.612
Total
phosphorus
(ppm)
53
72
82
21
24
17
52
38
Total
organic
nitrogen
(ppm)
149
235
270
156
64
53
192
117
a
Treatment
number
1GB
2GB
3GB
4GB
5GB
6GB
Averages
IQB-0
Deep bed
Volatile
solids
(ppm)
10700
12000
2700
2850
1980
7350
5190
Suspended
volatile
solids
(ppm)
191
1010
261
99
119
636
136
Suspended
solids
(%)
.026
.123
.036
.013
.016
.080
.018
Soluble
phosphorus
(ppm)
36
42
4
11
1
1
17
15
Nitrogenb
NH3
(ppm)
11
5
27
2
2
2
14
3
NO
NO;;
(ppm)
N02
(ppm)
PH
7.9
6.5
5.3
5.2
5.1
5.5
6.1
5.7
See footnote and treatment number on Table A7.
and N0_ were not determined.
£
72
-------
Table A9. INDIVIDUAL BLANCHING TRIALS FOR POTATOES
o
Blanching Treatment
treatment number
IQB-6.9
IQB-O
Deep bed
IQB-O
IQB-O
Averages
IQB-6.9
IQB-O
Deep bed
1POT
2 POT
3 POT
4 POT
5 POT
Belt loading
Heat
(kg /TCI)
3.56
5.76
11.76
5.76
5.08
3.56
5.51
11.76
Hold
(kg An2)
17.03
18.30
18.30
16.10
17.03
17.57
Effluent
generation
(l./case)
.754
1.31
1.25
1.40
.868
.754
1.20
1.25
Product
yield
a)
93.1
93.1
93.8
92.2
95.0
93.1
93.4
93.8
Solids lost
as product
(I)
.43
.60
.78
.60
.61
.43
.60
.78
IQB-6.9 means IQB with a 6.9% weight reduction prior to blanching,
IQB-O means IQB with no predrying.
Deep bed means deep bed steam blanching.
73
-------
Table A10. CHARACTERISTICS OF EFFLUENTS GENERATED
DURING POTATO BLANCHING
a
Treatment
number
1POT
2 POT
3 POT
4POT
SPOT
Averages
IQB-6.9
IQB-0
Deep bed
BOD_
(ppm}
5000
4030
3780
4260
4720
5000
4340
3780
COD
(ppm)
6340
4500
3640
4370
5790
6340
4890 -
3640
Total
solids
a)
0.930
0.746
1.01
0.707
0.856
0.930
0.770
1.01
Total
phosphorus
(ppm)
85
66
102
65
78
85
70
102
Total
organic
nitrogen
(ppm)
302
264
397
249
329
302
281
397
Treatment
number
1POT
2 POT
3 POT
4 POT
SPOT
Averages
IQB-6.9
IQB-0
Deep bed
Volatile
solids
(ppm)
7440
6010
8000
5720
5550
7440
5760
8000
Suspended
volatile
solids
(ppm)
775
1080
1490
171
1270
775
842
1490
Suspended
solids
(7c)
.081
.114
.156
.020
.133
.081
.089
.156
Soluble
phosphorus
(ppm)
48
46
57
41
52
48
47
57
Nitrogen
NH3
(ppm)
24
20
36
23
25
24
23
36
NO
NOf
(ppm)
12
11
16
10
13
12
11
16
N02
(ppm)
.29
.05
.09
.09
.05
.29
.06
.09
PH
6.9
7.1
6.9
7.0
6.9
6.9
7.0
6.9
See footnote and treatment number on Table A9,
74
-------
Table All. INDIVIDUAL BLANCHING TRIALS FOR BEETS
»a
Blanching
treatment
IQB-5.6
IQB-0
Deep bed
IQB-0
IQB-0
Averages
IQB-5.6
IQB-0
Deep bed
]
Treatment
number (
IB
2B
3B
4B
5B
ielt loading
Hea^
kg/m )
6.49
7.66
L6.40
6.88
6.44
6.49
7.00
16.40
Hold
(kg/m2)
27.62
32.55
29.28
27.47
27.62
29.77
--
Effluent
generation
(l./case)
1.48
1.84
1.68
1.61
1.74
1.48
1.73
1.68
/
Product
yield
(°l\
\'°)
86.3
87.8
89.4
90.0
88.8
86.3
88.9
89.4
Solids lost
as product
(%)
5.21
4.01
5.26
3.76
4.29
5.21
4.02
5.26
IQB-5.6 means IQB with a 5.6% weight reduction prior to blanching.
IQB-0 means IQB with no predrying.
Deep bed means deep bed steam blanching.
75
-------
Table A12. CHARACTERISTICS OF EFFLUENTS GENERATED DURING BEET BLANCHING
a
Treatment
number
IB
2B
3B
4B
5B
Averages
IQB-5.6
IQB-O
Deep bed
BOD5
(ppm)
29400
16700
21500
28600
19200
29400
21500
21500
COD
(ppm)
29700
22600
25700
19200
25000
29700
22300
25700
Total
solids
(%)
3.89
2.36
3.34
2.46
2.64
3.89
2.49
3.34
Total
phosphorus
(ppm)
145
91
136
98
95
145
95
136
Total
organic
nitrogen
(ppm)
556
349
492
378
379
556
369
492
Treatment
number
IB
2B
3B
4B
5B
Averages
IQB-5.6
IQB-O
Deep bed
Volatile
solids
(ppm)
33600
20800
29000
21500
23100
33600
21800
29000
Suspended
volatile
solids
(ppm)
378
156
214
224
170
378
183
214
Suspended
solids
(%)
.056
.017
.022
.027
.021
.056
.022
.022
Soluble
phosphorus^
(ppm)
Nitroeen
NH3
(ppm)
105
60
108
61
64
105
62
108
NO b
NOJ2
(ppm)
N02b
(ppm)
PH
6.6
6.6
6.5
6.7
6.6
6.6
6.6
6.5
See footnote and treatment number on Table All.
Interference in tests for soluble phosphorus, NO--N and NO -N.
76
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Table A13. INDIVIDUAL BLANCHING TRIALS FOR CARROTS
Blanching Treatment
treatment number (
IQB-0 1CAR
Deep bed 2CAR
IQB-0 SCAR
IQB-0 4CAR
Averages
IQB-0
Deep bed
Belt loading
Hea|
kg An )
9.86
16.01
9.86
8.64
9.45
16.01
Hold
(kg/m2)
41.82
41.82
36.60
40.06
Effluent
generation
(l./case)
1.30
1.49
1.27
1.27
1.28
1.49
Product
yield
a)
91.6
88.4
91.9
91.9
91.8
88.4
Solids lost
as product
C7o)
1.54
2.77
1.86
2.39
1.93
2.77
a
IQB-0 means IQB without predrying.
Deep bed means deep bed steam blanching.
77
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Table A14. CHARACTERISTICS OF EFFLUENTS GENERATED DURING CARROT BLANCHING
a
Treatment
number
1CAR
2CAR
3CAR
4CAR
Averages
IQB-0
Deep bed
BOD
(ppm}
8340
11700
10200
12500
10300
11700
COD
(ppm)
10600
12100
10700
16400
12600
12100
Total
solids
(7=)
1.02
1.56
1.25
1.61
1.29
1.56
Total
phosphorus
(ppm)
66
100
81
106
84
100
Total
organic
nitrogen
(ppm)
439
623
512
649
533
623
Treatment
number
1CAR
2 CAR
3CAR
4CAR
Averages
IQB-0
Deep bed
Volatile
solids
(ppm)
8520
12700
10600
12500
10600
12700
Suspended
volatile
solids
(ppm)
170
436
283
835
429
436
Suspended
solids
(%)
.034
.044
.029
.097
.053
.044
Soluble
phosphorus
(ppm)
59
100
80
97
79
100
Nitrogen
NH3
(ppm)
39
56
40
48
42
56
NO
NO£
(ppm)
30
44
38
49
39
44
N02
(ppm)
25
36
33
29
29
36
PH
5.1
5.8
5.9
5.5
5.5
5.8
See footnote and treatment number on Table A14.
78
*U.S. GOVERNMENT PRINTING OFFICE: 1974 546-318/377 1-3
-------
SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
3. Accession No.
W
4. Title
WASTEWATER ABATEMENT IN CANNING VEGETABLES BY IQB
BLANCHING
7. Authorts)
Lund, Daryl B.
University of Wisconsin
Department of Food Science
Madison, Wisconsin 53706
5- R^pew tww
8, PerfortttJuc Organization
10. Project No.
^
11. Contract/Giant No.
S-801484
1L Type -of Report and .
f'caod
1S. Supplementary Notes
Environmental Protection Agency Report Number: EPA-660/2-74-006, April 1974
16. Abstract
A study on the efficacy of a new blanching system, Individual Quick Blanch (IQB),
as applied to vegetables prior to canning was conducted. Peas, corn, lima beans,
green beans, potatoes, carrots and beets were adequately blanched by IQB. Compared
to deep bed steam blanching or pipe blanching, IQB generally resulted in a signifi-
cant reduction in effluent. Slight drying of the vegetables before IQB reduced
effluent even more; however, product quality was adversely affected In most cases.
It was demonstrated that the IQB process can significantly reduce effluent volume
and BOD generation in the blanching operation while adequately fulfilling the
objectives of blanching. Recommendations for commercial development of IQB are
given. '
17a. Descriptors
Blanching, Individual Quick Blanching, Pollution Abatement, Water Pollution,
Cannery Wastes, Vegetable Processing Wastes
17b. identifiers
I7c. COWRR Field & Group-
Availability
Send To:
WATER RESOURCE* SCIENTIFIC INFORMATION CENTER
UA DEPARTMENT OF THE INTERIOR
WASHINGTON. D.C. M240
Abstractor
Daryl B. Lund
University of Wisconsin-Madison
WRSlC 102 (REV. JUNE 1971]
G P O
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