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 ------- 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. ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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. ------- 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. ------- 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 ------- 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 ------- 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 ------- 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. ------- 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. ------- 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 ------- 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. ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- |