0 HLBBMNEBNNQQ— ,,N_ SQ V if wmw_:-__:_._:_: LLL LL LL LLLLLLLLLL L LIBRARY Michigan State University LLLLLLLL HEELS This is to certify that the thesis entitled FOODSERVICE SYSTEMS: SENSORY AND MICROBIAL QUALITIES OF PRECOOKED CHILI AND SOUP STORED CHILLED OR FROZEN FOR 30 DAYS IN TWO TYPES OF CASINGS presented by Sharon Marie Donnenwerth has been accepted towards fulfillment of the requirements for M.S. Institution Administration degree in Major professor Date 2/20/86 0-7639 MS U is an Affirmative Action/Equal Opportunity Institution MSU LIBRARIES m RETURNING MATERIALS: Place in book drop to remove this checkout from your record. FINES will be charged if book is returned after the date Stamped below. FEB 1519951 Ml; 171993 E;% . (199$? a ‘éJ E 18 m. FOODSERVICE SYSTEMS: SENSORY AND MICROBIAL QUALITIES OF PRECOOKED CHILI AND SOUP STORED CHILLED OR FROZEN FOR 30 DAYS IN TWO TYPES OF CASINGS BY Sharon Marie Donnenwerth A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Food Science and Human Nutrition 1986 ABSTRACT FOODSERVICE SYSTEMS: SENSORY AND MICROBIAL QUALITIES OF PRECOOKED CHILI AND SOUP STORED CHILLED OR FROZEN FOR 30 DAYS IN TWO TYPES OF CASINGS BY Sharon Marie Donnenwerth Microbial and sensory qualities of soup and chili packaged in two types of plastic casings (polyethylene/ nylon/polyethylene or P/N/P; polyethylene or PE) were evaluated after 30 i_4 days of chilled (—l0 i 1°C) or frozen storage (-70 : 1°C). All products were in excellent microbial condition at point of service. Consumer panels indicated no packaging preference for chili products but P/N/P was preferred for soup regardless of storage condition. Trained taste panels found few significant differences among chili products. Texture of vegetables in chilled P/N/P soup was rated significantly higher than for frozen P/N/P soup. Frozen PE soup was rated higher than frozen P/N/P soup for: color of vegetables, integrity of vegetables, texture of vegetables and aftertaste. Results indicated that PE casings were unacceptable for chilled storage while P/N/P casings were acceptable for chilled or frozen storage. This work is dedicated to God our Father; to my parents for their love and support; and in memory of my dear friend, Debbie Minster Jones, who during her fight with cancer taught me a lot about faith, hope and perseverance. ii ACKNOWLEDGEMENTS The author wishes to thank her graduate committee; Dr. Carol Sawyer, Dr. John Gill, Professor Jean McFadden and Dr. Mary Zabik for their guidance and assistance. A special thanks to Carol Sawyer for her professional guidance and assistance throughout my graduate program. The author wishes to thank the Cryovac Division of the W. R. Grace Company for funding the project. A special thanks to Randy Koteles for his technical assistance. Also, a special thanks to University Hospital in Cleveland for producing the chili and soup, and for allowing us to observe production of the chili and soup. Lastly, the author wishes to thank Wen-Syi Lin, Ph.D., Candidate for his assistance with microbial analysis at MSU and Jennifer Yuan, Laboratory Assistant, for her assistance with taste panels. iii TABLE OF CONTENTS LIST OF TABLES vii LIST OF FIGURES ix I. INTRODUCTION 1 II. REVIEW OF LITERATURE 4 A. Alternative Foodservice Systems 4 B. Microbial Safety of Foods in Alternative Foodservice Systems 6 C. Development of Cook/Chill Foodservice Systems 7 D. Development of Cook/Freeze Foodservice Systems 10 E. Comparisons of Cook/Chill and Cook/Freeze Foodservice Systems: Microbial Quality 11 F. Hazard Analysis, Critical Control Points 17 G. Sensory Quality Defined 19 H. Comparison of cook/Chill and Cook/Freeze Foodservice Systems: Sensory Quality 19 I. Packaging Materials 28 J. Common Food Packaging Films 31 III. MATERIALS AND METHODS 34 A. Packaging Materials 35 B. Preparation of Experimental Products 36 l. Chili 37 2. Vegetable Soup 40 C. Pumping Experimental Products Into Casings 40 D. Chilling Filled Casings 41 iv J. K. L. Shipment of Products Product Storage Microbial Analyses Reheating of Products Consumer Taste Panels Trained Taste Panel Statistical Analysis: Consumer Taste Panel Statistical Analysis: Trained Taste Panel IV. RESULTS A. B. C. D. Product Storage Microbial Analyses Reheating of Products Consumer Taste Panels 1. Chili Comparisons 2. Soup Comparisons Trained Taste Panel 1. Sensory Evaluation of Chili 2. Sensory Evaluation of Soup V. DISCUSSION A. B. C. D. Product Storage: Temperature Microbial Analyses Reheating of Products Sensory Quality of Chilled and Frozen Chili and Soup E. Consumer Taste Panels 97 l. Chili Comparisons 98 2. Soup Comparisons 101 F. Trained Taste Panel 107 1. Sensory Evaluation of Chili 108 2. Sensory Evaluation of Soup 112 VI. CONCLUSIONS AND RECOMMENDATIONS 116 A. Recommendations for Future Research 116 VII. APPENDIX 120 142 VIII. LIST OF REFERENCES vi i 10. LIST OF TABLES Mean temperature and relative humidity for two batches of chili and soup stored chilled and frozen in C-300 and PE casings. 60 ABC Laboratories: Microbial analyses of chilled and frozen chili and soup stored for 30 :_4 days in C-300 and PE casings. 62 MSU Labs: Mean aerobic plate counts (APC) for chilled and frozen chili and soup stored for 30 i 4 days in C-300 and PE casings. 67 Approximate reheating times in hot water for chilled and frozen chili and soup in C—300 and PE casings. 68 Consumer taste panel results for comparisons of chilled and frozen chili and soup packaged in C—300 and PE casings. 72 Trained Taste Panels: Treatment combination (T.C.) mean scores, standard error of T.C. means and significance of F values for sensory quality of chilled and frozen chili in C-300 and PE casings. 79 Trained Taste Panels: Comparison of treatment combination (T.C.) mean scores for sensory evaluation of chilled and frozen chili packaged in C-300 and PE casings. 81 Trained Taste Panels: Treatment combination (T.C.) mean scores, standard error of T.C. means and significance of F values for sensory quality of chilled and frozen vegetable soup in C—300 and PE casings. 83 Trained Taste Panels: Comparison of treatment combination mean scores for sensory evaluation of chilled and frozen vegetable soup packaged in C—300 and PE casings. 84 Observed frequency and expected values for consumer taste panel responses to the consumer comparison of chilled C-300 chili versus chilled PE chili. 106 vii A-l. Standardized recipe for chili con carne used at University Hospital, Cleveland, Ohio. 120 A-2. Standardized recipe for vegetarian vegetable soup used at University Hospital, Cleveland, Ohio. 121 A-3. Ballot for the pilot consumer taste panel. 122 A-4. Location and comparisons for consumer taste panels to compare quality of chili and soup held chilled and frozen for 30 days in C-300 and PE casings. 123 A—5. Ballot for consumer taste panel to compare chilled and frozen chili and soup in C—300 or PE casings. 125 A-6. Quantitative descriptive analysis (QDA): preliminary analysis of sensory characteristics. 126 A-7. Trained taste panel: ballot for chili. 127 A—8. Trained taste panel: ballot for vegetarian vegetable soup. 128 A-9. ABC Laboratories: Microbial analyses of the first batch of chilled and frozen chili and soup stored for 30 days in C-300 and PE casings. 129 A—lO. ABC Laboratories: Microbial analyses of the second batch of chilled and frozen chili and soup stored for 30 days in C—300 and PE casings. 130 A—ll. MSU Labs: Aerobic plate counts (APC) for chilled and frozen chili and soup stored for 30 days in C-300 and PE casings. 131 A-12. Sex and product preference of consumer panelists for chilled and frozen chili in C-300 or PE casings. 132 A-l3. Sex and product preference of consumer panelists for chilled and frozen soup in C-300 or PE casings. 133 A—l4. Age and sex of consumer taste panelists by panel location. 134 viii LIST OF FIGURES Hospital cook/chill and cook/freeze foodservice systems: Food product flow to compare microbial and sensory qualities of cooked chili and vegetable soup stored chilled or frozen in C-300 or PE casings. 38 Decision chart for the statistical significance of consumer panelists responses to comparisons of chilled and frozen chili and soup in C—300 and PE casings. 56 Consumer panelists responses to preference test for chilled C-300 chili versus frozen C-300 chili. 135 Consumer panelists responses to preference test for chilled PE chili versus frozen PE chili. 136 Consumer panelists responses to preference test for chilled C-300 chili versus chilled PE chili. 137 Consumer panelists responses to preference test for frozen C-300 chili versus frozen PE chili. 138 Consumer panelists responses to preference test for chilled C-300 soup versus frozen C-300 soup. 139 Consumer panelists responses to preference test for chilled PE soup versus frozen PE soup. 140 Consumer panelists responses to preference test for (a) chilled C-300 soup versus chilled PE soup and (b) frozen C-300 soup versus frozen PE soup. 141 ix Chapter I INTRODUCTION Cook/chill and cook/freeze production methods have been used to improve the sensory and nutritional qualities of foods served in hospital and school foodservice systems, when compared to a conventional foodservice system. In cook/chill and cook/freeze foodservice systems entrees are produced in bulk, chilled and held chilled or frozen, prior to reheating and service to the customer. Since the introduction of cook/chill and cook/freeze technology in the 1960's and 1970's (Bjorkman and Delphin, 1966; McGuckin, 1969; Glew, 1973), until the present, there has been a debate as to which method of storage was better to preserve the sensory, nutritional, and microbial qualities of cooked foods. Recent develOpments in plastic packaging and rapid chilling of cooked foods has resulted in a longer shelf life for chilled foods. Manufacturers of plastic food films have been able to develop plastic packaging with a wide range of preperties by coextruding various resins within micro-seconds of each other, biaxially orienting them and subjecting them to irradiation (Ramey, 1984). Specific resins were chosen for their barrier prOperties, shrinkability, flexibility, strength, thermoformability and clipability to form a specific package for a given application. Plastic casings with a tolerance for wide 1 2 variations in temperature made possible rapid chilling of cooked foods packaged in plastic casings at 82°C and cooled to 35°C in 30 minutes (Ramey, 1984). Microbial growth was prevented during cooling and during product storage at a refrigerated temperature of -2°C to 0°C. The development of packaging which could be filled with food products at temperatures above pasteurization temperature (282°C), rapidly chilled to 35°C in 30 minutes, and stored at a lower refrigerated temperature, increased the shelf life of chilled foods from 72 hours to 60 days (Ramey, 1984). Therefore, the shelf life of chilled foods was closer to the shelf life of frozen foods. The purpose of the present study was to determine if a difference in sensory and/or microbial qualities existed between chilled and frozen foods packaged in either the Cryovac C-300@>(Cryovac Division, W. R. Grace Co., Duncan, S. C.) casing or polyethylene (PE) casings. The Cryovac C—300 casing was a multilayer coextrusion of polyethylene/nylon/polyethylene with a high oxygen barrier. The PE casing was compared to the C—300 casing because it was marketed for uses similar to the C—300 but had a lower oxygen barrier. The PE casing was cheaper than the C—300 casing but was not as strong as the C—300 casing. The PE casing required careful handling during filling of the casings, cooling, storage and reheating. Thus, the C—300 casing was more practical for a foodservice operation because it was 3 stronger and could be chilled in a mechanical chiller and reheated more rapidly than the PE casing. Chapter II REVI EW OF LITERATURE Various foodservice systems have evolved from the traditional foodservice system during the past twenty years. Several foodservice systems are defined below. This review of literature will focus on the development of the cook/chill and cook/freeze foodservice systems. Several studies comparing the sensory and microbial qualities of foods prepared in cook/chill and cook/freeze foodservice systems will be summarized. Recent advances in packaging technology which resulted in new food packaging films for use in cook/chill or cook/freeze foodservice systems will also be discussed. Alternative Foodservice Systems In the conventional foodservice system, foods were prepared daily, on—site, for service to the customer. Problems associated with the conventional foodservice system were shortages of skilled labor; increasing labor costs; inefficient use of equipment and staff with peak production periods and slack times in the work day; and poor sensory quality of foods held hot for long periods of time during assembly and distribution of meals (Glew and Armstrong, 1981). The cook/chill foodservice system began developing in the 1960's as an alternative to the conventional foodservice 4 5 system. In the cook/chill foodservice system, foods were cooked, chilled and held chilled for 24 hours before service to the customer (Unklesbay et a1., 1977). The cook/freeze foodservice system began developing in the 1970's as another alternative to the conventional foodservice system. In the cook/freeze foodservice system, foods were cooked, chilled, frozen and held frozen from one day to six months before service to the customer. Unklesbay et a1. (1977) described food product flow in four foodservice systems: (a) conventional, (b) commissary, with cook/chill or cook/freeze production methods, (0) ready prepared foods and (d) assembly/serve. Conventional foodservice systems which used food products at all points along the food processing continuum from little or no processing to complete processing evolved from traditional foodservice operations. The traditional foodservice operation was labor intensive with meat processing, baking and vegetable preparation done on the premises. Conventional foodservice operators reduced labor requirements by purchasing pre—portioned cuts of meat, frozen potatoes, vegetables and desserts, confectionery mixes, and prepared fresh salads when available. Foods in the conventional foodservice system were prepared daily, on-site and held chilled or at serving temperature until service (Unklesbay et a1., 1977). The main feature of the commissary foodservice system was that production and service areas (referred to as 6 satellites) were located geographically in separated facilities. Commissary operations tended to acquire food products which had little or no processing. Products were prepared, packaged in bulk or individual servings, held frozen, chilled or hot; and transported to satellite facilities for reheating and service to customers (Unklesbay et a1., 1977). In ready prepared foodservice systems, completely prepared foods were purchased or menu items were prepared and stored chilled or frozen, always ready for final assembly and/or reheating before service to consumers within the same facility. In assembly/serve foodservice systems, frozen foods were purchased in bulk, pre—portioned or pre-plated forms. Foods were then portioned, assembled, transported, heated and served. Cook/chill and cook/freeze production techniques were used in both commissary and ready-prepared foodservice systems (Unklesbay et a1., 1977). Microbial Safety of Foods in Alternative Foodservice Systems Use of cook/chill and cook/freeze production techniques have caused concern for the microbial safety of foods. Much of the concern about microbial safety of chilled foods has focused on the time that food products were in the temperature range favoring microbial growth (20°C to 50°C) during the chilling process (Millross et a1., 1974). Longree (1972) stated that cooked foods should be chilled to 7°C or below within four hours, to assure minimal growth of 7 bacteria. Much research has been done to determine if various chilling methods in foodservice systems were capable of meeting that standard (Tuomi et a1., 1974; Bunch et a1., 1976; Cremer and Chipley, 1977; Rollin and Matthews, 1977; Bobeng and David, 1978a; Bryan and McKinley, 1979; and Dahl et a1., 1980). Another concern about microbial safety of cooked foods was the possible growth of microbes during chilled storage, especially if products were held chilled for more than three days. Shelf life of chilled foods was often compared to shelf life of frozen foods and was considered a limitation of chilled foodservice systems (Livingston and Chang, 1979). Recent advances in rapid chilling of foods from 82°C to 0°C in less than one hour, with storage of chilled foods at 2°C, increased shelf-life of chilled foods from four to six days up to six weeks (Livingston and Chang, 1979). Development of Cook/Chill Foodservice Systems One of the earliest uses of cook/chill production techniques was the Nacka System in Sweden (Bjorkman and Delphin, 1966). Hot entrees and vegetables were cooked to 80°C, packaged in plastic bags (five portions per bag), air was extracted from the bag and the bag was sealed. Next, food products in bags underwent "pasteurization" by immersion in boiling water (100°C) for three minutes. The purpose of pasteurization was to kill disease causing microorganisms which could have survived the cooking process 8 or recontaminated the product during the packaging process. Bags of product were then passed through a cooling tunnel for one hour. Bags were dried and stored in the refrigerator at 4°C for up to three weeks. Bags were reheated in boiling water for 30 minutes. A panel of experts and laymen judged the food quality to be comparable with that of conventionally prepared industrial food. Bjorkman and Delphin (1966) reported that in five years of production more than 10,000 bacterial tests on foods produced in this system were tested and found to be within acceptable limits. However, Bjorkman and Delphin (1966) did not define acceptable limits for microbial counts, nor did they report the methods used in the microbial analyses. McGuckian (1969) reported use of a variation of the Nacka system by three hospital foodservice systems in South Carolina called the A.G.S. system (abbreviated for the names of the hospitals: Anderson, Greenville and Spartansburg). In the A.G.S. system, ingredients were assembled either raw or partially cooked, portioned, packaged under vacuum, pasteurized, and cooked for specified times in a thermostatically controlled water bath. The A.G.S. system differed from the Nacka system in that foods were packaged and cooked (or cooking was completed) in the bags, which would prevent recontamination of products following cooking. After cooking, packaged foods were chilled in an ice water tank, stored refrigerated at —2°C to 0°C for a shelf-life of at least 60 days (McGuckian, 1969). In the 9 A.G.S. system, foods were transported to satellites, reheated in the bags in a water bath for 30 to 40 minutes until product temperature was 271°C. When the meal was plated, the entree and vegetables were given an additional heat treatment for 10-20 seconds in a microwave oven to ensure that food items were hot. The next significant event in the deve10pment of cook/chill foodservice systems was the elimination of the pasteurization step used in the Nacka and A.G.S. systems. The Food Laboratory at Natick tested quality of cook/chill foods processed with or without pasteurization and determined that quality of food was similar without pasteurization (Matthews, 1977). Researchers at the Natick Laboratory reported that cooked or baked menu items withstood refrigerated (4°C) storage for up to nine days without spoilage or excessive microbial growth. Sensory evaluation of selected meats, fruits, vegetables and bakery items indicated that food quality was somewhat better with a chill system after storage for nine days than with a frozen system. Kaud (1972) reported the use of a cook/chill foodservice system in which foods were prepared on-site for 24 hours in advance of service, chilled in bulk, portioned, stored chilled and reheated in microwave ovens in patient areas. Kaud reported improved food quality (hot foods hot, cold foods cold), decreased labor costs and increased productivity (measured by meals per man hour) resulted from 10 implementation of the cook/chill foodservice system compared to the previous decentralized foodservice system with kitchens on each floor. Development of CookAFregge Foodservice Systems One of the earliest uses of a cook/freeze foodservice system in a hospital was at Leeds Hospital in 1970 (Glew and Armstrong, 1981). Three foodservice systems (conventional with choice; conventional without choice; and cook/freeze with choice) were used in sequence, with a survey of consumer acceptance of food quality in each system conducted by mailing questionnaires to patients after they were discharged from the hospital. Consumers rated the cook/freeze system equal to the conventional system when a choice of entrees was offered in both systems. Glew and Armstrong (1981) identified two main problem areas associated with conventional foodservice systems as ineffective use of labor and equipment, with peak periods of utilization and slack periods with under—utilization of staff and equipment; and the long hot holding periods for foods during preparation, plating and distribution of patient meals. By centralizing food production, preserving cooked food and distributing it to service points, many of the problems previously associated with institutional feeding could be eliminated (Glew and Armstrong, 1981). Millross et a1. (1974) reported on the nutritional, microbial and economic implications in switching from a 11 conventional to a cook/freeze foodservice system. Although no details of methods were given, Millross et a1. (1974) reported that nutrient retention (as measured by available lysine, and ascorbic acid content of cooked foods) was increased in the cook/freeze system, and microbial safety in the cook/freeze system was no more hazardous than in the conventional system. The capital costs in the cook/freeze system were higher than in the conventional system and were not offset by savings in wages. Comparison of Cook/Chill and CookZFreeze Foodservice Systems: Microbial Qualitv Microbial safety of foods served in foodservice systems is a concern because many foods are capable of supporting microbial growth which could result in outbreaks of foodborne illnesses. A summary of surveillance data on the cause of outbreaks of foodborne disease associated with meat and poultry from 1968 to 1977 showed that imprOper cooling of cooked meat or poultry was the cause of the outbreak in 48% of the cases reported (Bryan, 1980). Much of the concern about the microbial safety of foods prepared in cook/chill or cook/freeze foodservice systems has focused on the standard for cooling of cooked foods recommended by Longree (1972). Longree (1972) stated that cooked foods should be cooled to g7°C in four hours or less. Several researchers have studied the cooling time required for cooked products to reach 37°C in cook/chill and cook/freeze foodservice Ill’il Iill‘l‘i.‘ 12 system (Tuomi et a1., 1974; Bunch et a1., 1976; Rollin and Matthews, 1977; Nicholanco and Matthews, 1978). Bryan (1980) summarized surveillance data on outbreaks of foodborne disease associated with meat and poulty from 1968 to 1977. ImprOper cooling of cooked meat and poultry was the cause of the outbreak in 48% of all cases reported that were associated with meat and poultry. Other causes of foodborne outbreaks related to meat and poultry were: holding prepared foods more than 24 hours before service, 27%; infected persons touching cooked foods, 23%; inadequate reheating of cooked foods, 20%; imprOper hot storage of foods, 19%; and cross—contamination of cooked and raw foods, 15% (Bryan, 1980). Of those outbreaks reported, 65% resulted from foods eaten in foodservice establishments, 31% from foods prepared in the home and 4% from mishandling in food processing plants (Bryan, 1980). Clearly there is good reason to be concerned about the microbial quality of foods served in any foodservice system. It should also be noted that imprOper cooling of cooked meat and poultry was the cause of the outbreak in 48% of the cases reported. Cooling of cooked foods is an important step in both cook/chill and cook/freeze foodservice systems in preventing the growth of disease causing (pathogenic) microorganisms. Several studies of cook/chill and cook/freeze foodservice systems have focused on the time-temperature relationship in cooked foods during cooling, freezing and chilled or frozen storage (Tuomi et a1., 1974; Bauman, 1974; 4 y . .. . a . . L .. I i . . . . . I“ 1 V _ .. . 3 4 i; c A I ... . t. l v u» .~ . .. _, .M . ., . C , . .J . I. a A l. C \ . . . . .. l s ., , fl . . a . . 1 . .. . . i . . , t .. . .. .1 .. ‘4 V .4 \ . 14 o . .QJ . J _ . \ [A s . l4 . v . c . .u. . . e a . . x. . . 4 u. I. 1 ~ , I \ . u 4 . — v .. J . a 5 i. . . .. . . . c . . n” . . J. . . .. 1 .. U .n . . .u pie 1 ~ . e 4 . . M a . u ,l 1).. V . ~ A .p A . . . . ... _ _ . _ s J ... . .. . . . . v . H b i . _ u . . L .. _ :1 .. r . . i 4 . . . . . u t . \ :1le 13 Bunch et a1., 1976; Rollin and Matthews, 1977; Nicholanco and Matthews, 1978; Bobeng and David, 1978a; Bobeng and David, 1978b). Microbial quality of cooked foods was controlled through adherence to time—temperature standards to minimize the time that cooked foods were in the temperature zone favorable for microbial growth, 21°-46°C for foodborne pathogenic microorganisms (Bryan and McKinley, 1979). Longree (1972) recommended that cooked foods be cooled to 37°C within four hours to prevent the rapid growth of microorganisms during the cooling of cooked foods. Longree's time—temperature standard for the cooling of cooked foods has been tested by several researchers (Bunch et a1., 1976; Rollin and Matthews, 1977; Nicholanco and Matthews, 1978; Bobeng and David, 1978a; Bobeng and David, 1978b). Kossovitsas et a1. (1973) compared the effect of chilled holding and frozen storage on the sensory and microbial quality of cooked foods. Chicken a la King, Codfish in Cream Sauce and Broccoli with Cheese Sauce were prepared according to commercial recipes, packaged in individual mylar polyethylene film pouches, vacuumized, pasteurized, cooked and stored chilled at 2°C or frozen at -23°C. Chilled products were packaged, pasteurized and cooled by the method used in the Nacka System reported by Bjorkman and Delphin (1966). Frozen samples were not vacuumized or pasteurized. Samples for microbial study were inoculated with Clostridium perfringens and Salmonella Type 14 Paratyphi B. After 15 and 30 days of storage, all reheated, refrigerated samples gave negative results for the two organisms while frozen samples gave negative results for C. perfringens but positive results for Salmonella. After 15 days of storage, the taste panel could not detect any significant difference in appearance, flavor and consistency between frozen and refrigerated samples, while fresh controls were graded superior to either of the stored samples. At 30 days of storage, refrigerated samples were no longer acceptable as judged by the panel, while frozen samples where acceptable, but were inferior to fresh samples (Kossovitsas et a1., 1973). Tuomi et a1. (1974) studied the microbial quality of ground beef gravy in a school satellite foodservice system. Cooked gravy was cooled to 43°C and inoculated with Clostridium perfringens before being packed in bags and refrigerated for 16 hours at 6°C. The number of viable cells after 16 hours in the refrigerator was influenced by the first six hours of cooling when the temperature of the gravy was in the range that permitted growth of C. perfringens (18° - 50°C). When gravy was reheated in a compartment steamer to an internal end temperature of 74°C, no viable cells of C. perfringens were found (Tuomi et a1., 1974). Although the gravy stayed in the temperature zone favorable for microbial growth longer than the four hours recommended by Longree (1972), once the gravy was reheated for service no viable cells of C. perfringens were found. 15 Bunch et a1. (1976) determined the microbial quality of beef-soy loaves (25% soy) when processed according to system procedures in a hospital cook/chill foodservice system. Beef-soy loaves were initially cooked to 60°C before cooling and chilled storage at 5° i_3°C for 24, 48, or 72 hours. During chilling of beef-soy loaves, the internal temperatures at the geometric center of the loaves did not reach 37°C in less than four hours as recommended by Longree (1972). Samples removed from loaves after chilled storage showed the largest increase in aerobic bacteria occurred during cooling. The largest increase in numbers of bacteria occurred when holding was for 72 hours. However, heating samples to 80°C in a microwave oven decreased the numbers of aerobic bacteria by an average of 100,000 organisms per gram. Final bacterial counts after microwave heating were all acceptable, so beef—soy loaves were considered to be in excellent microbial condition when they reached the consumer (Bunch et a1., 1976). Rollin and Matthews (1977) studied the temperature history of beef-soy loaves (25% soy) in a hospital cook/chill foodservice system. The purpose of their study was to determine if refrigeration equipment used in hospital/schools could meet the standard for cooling cooked entrees to 37°C in less than four hours as recommended by Longree (1972), and maintaining food temperature in the Optimal range for microbial growth (16°-49°C) for 32 hours. Beef-soy loaves were cooled in pans in a walk—in l6 refrigerator at 4i,3°C and required an average of 7-11 hours for the geometric center of the food mass to reach 37°C. Rollin and Matthews (1977) concluded that it was not possible to chill the beef-soy loaves through the 49°-16°C temperature range within 2 hours, nor was it possible to chill the beef-soy loaves to 7°C or less in four hours in a typical walk—in refrigerator. Nicholanco and Matthews (1978) evaluated the quality of beef stew in a hospital cook/chill foodservice system. After preparation, 6 liters of beef stew were placed in a pan, covered with plastic wrap and placed in the walk-in refrigerator to cool. Temperature of the walk-in fluctuated from 6°C—10°C during the first nine hours of cooling. The temperature of the beef stew was >7°C during the first nine hours of cooling. At the end of 22 hours, the mean temperature in the stew was 5°C and the refrigerator temperature was 7°C. The temperature of the beef stew did not reach 37°C within the four hours recommended by Longree (1972). When the beef stew was reheated in microwave ovens, four samples did not reach the temperature recommended for microbial safety (74°C). Aerobic plate counts were highest during chilled storage and were lowest immediately after preparation and after reheating in microwave ovens. Mean aerobic plate counts during chilled storage ranged from 8.4 x 104 CFU/gm after 3 hours chilled storage to 14.5 x 104 CPU/gm after 19 hours chilled storage. The mean aerobic plate count was 6.6 x 104 CFU/gm both at the end of 17 preparation and after microwave reheating. In summary, several researchers (Tuomi et a1., 1974; Bunch et a1., 1976; Rollin and Matthews, 1977; Nicholanco and Matthews, 1978) who studied the time—temperature relationship of cooked products during chilling reported that cooked products did not reach an internal temperature of 7°C or less in four hours as recommended by Longree (1972). Although the cooked foods did not meet the time—temperature standard for cooling recommended by Longree (1972), the foods were in excellent microbial condition after reheating prior to service to the consumer. Hazard Analysis, Critical Control Points Until 1970-74, time-temperature relationships during cooling of cooked products were used to control the microbial quality of cooked products. Bobeng and David (1978a) adapted the idea of hazard analysis and critical control points from the food processing industry which had used hazard analysis for a number of years. Bauman (1974) defined hazard analysis as the identification of sensitive ingredients, critical process points, and relevant human factors as they affect product safety. Critical control points were those processing determiners where loss of control would result in an unacceptable food safety risk (Bauman, 1974). Bobeng and David (1978a) applied hazard analysis to foodservice systems to control microbial quality. Specific time—temperature IIIIIII‘.‘ 18 recommendations were chilling foods to 37°C (45°F) in four hours or less, with chilled storage at 37°C for 20 hours or less and reheating foods to 74°C—77°C (165-170°F). For freezing cooked foods, time of freezing should be < 90 minutes at 3728°C (—4°F), frozen storage 38 weeks at 3718°C (0°F), minimal thawing time at 37°C (45°F) and reheating frozen foods to 74-770c (Bobeng and David, 1978a). Bobeng and David (1978b) assessed the quality of beef loaves prepared in a laboratory simulation of conventional, cook/chill and cook/freeze hospital foodservice systems to determine the effectiveness of Hazard Analysis Critical Control Point (HACCP) models. Aerobic plate counts (APC) were used to indicate microbiologic quality. APC's indicated that beef loaves prepared in all three systems had excellent microbial quality. The only problem with time-temperature standards in this study was that 5 hours were required for chilling loaves in the cook/chill system to 37°C instead of the recommended four hours (Bobeng and David, 1978b). Research has shown that foods prepared in a cook/chill foodservice system were of acceptable microbial quality at the point of service. However, the least amount of control appeared during the cooling process, with many products not being cooled to 37°C in 34 hours as recommended by Longee (1972). 19 Sensory Qpalitv Defined Sensory evaluation of foods has long been used to objectively measure the quality characteristics of foods. Various methods and techniques, such as paired—comparison, ranking, threshold, flavor profile analysis, Hedonic scale rating and food acting rating scale, have been used to evaluate specific characteristics of food quality (IFT Sensory Evaluation Division, 1981). Sensory evaluation can be used as a quality control tool in foodservice systems. Cichy (1983) stated that the average consumer associates quality with subjective personal preferences, as something liked or disliked, excellent, great or good. Sensory quality can be defined as an orderly classification of the chemical and physical characteristics of a product (Cichy, 1983). Sensory evaluation identifies the presence or absence of perceptible differences, pinpoints the important sensory characteristics of a product in a fast, quantifiable manner; and identifies particular problems that cannot be detected with other analytical techniques. Comparison of Cook/Chill and CookZFreepe Foodservice Systems: Sensory Quality Several researchers have compared the sensory quality of foods prepared in cook/chill and cook/freeze foodservice systems (Jakobsson and Bengtsson, 1972; Zallen et a1., 1975; Bunch et a1., 1976; Bobeng and David, 1978b; Zacharias, 20 1979; Cremer, 1983; McDaniel et a1., 1984). Sensory quality of freshly prepared foods has usually been rated higher than chilled or frozen foods. Some researchers have reported significant differences in sensory quality between chilled and frozen foods, while others have reported no significant differences in sensory quality for chilled or frozen foods. Studies comparing the sensory quality of foods prepared in cook/chill and cook/freeze foodservice systems are summarized below. Jakobsson and Bengtsson (1972) compared the quality of frozen and refrigerated sliced beef in a laboratory simulation of commercial processing practices in Sweden. The study consisted of three treatments: (1) vacuum packaging with 0.5 m1 headspace volume followed by pasteurization (80°C) and chilled storage at 3°C and 8°C for up to 21 days; (2) vacuum packaging with 9 m1 headspace volume followed by pasteurization and chilled storage at 3°C and 8°C for up to 21 days; and, (3) vacuum packaging with 9 m1 headspace volume followed by frozen storage at -20°C for two months (Jakobsson and Bengtsson, 1972). For sensory evaluation a nine grade preference scale for flavor and a nine grade intensity scale for off-flavor, juiciness and tenderness (1=extreme1y poor, no off—flavor and 9=extremely good, juicy or tender) was used. Panelists evaluated chilled, frozen and a fresh reference sample after 1, 7, l4, and 21 days of storage. Quality decreased with increasing time of refrigerated storage with flavor scores for 21 refrigerated beef significantly lower than flavor scores for frozen beef. Frozen beef was rated significantly higher for juiciness than was refrigerated beef. In all cases fresh beef was rated higher than frozen or refrigerated beef. Quality of cooked beef slices refrigerated at 3°C and 8°C were similar with quality deteriorating slightly faster at 8°C (Jakobsson and Bengtsson, 1972). Zallen et al. (1975) compared the microbial and sensory quality of beef loaves (25% fat) prepared according to three procedures used in hospital foodservice systems; cook/chill, cook/pasteurized/chilled, and cooked/frozen/thawed (and refrigerated for 0 to 9 days). Beef loaves were initially cooked to an endpoint temperature of 74°C before being chilled or pasteurized (74°C) and placed in chilled storage (0°C and 6°C) or frozen storage (—18°C) for up to three weeks. A seven member trained taste panel evaluated beef loaves for odor, appearance, flavor and juiciness on a 9 point scale, with 9 the high score. Panelists evaluated four samples, fresh, chilled, chilled/pasteurized, and frozen/thawed, at each session. The fresh (reference) loaves received significantly (p < 0.01) higher scores for odor, appearance, flavor and juiciness than any of the cooked loaves which had been stored (Zallen et a1., 1975). Scores for chilled and chilled/pasteurized loaves were not significantly different. Scores for frozen/thawed loaves were significantly lower (p < 0.01) than for the other stored 22 loaves. Results of the taste panel indicated that there were no significant differences in quality characteristics for loaves stored chilled at 0°C and 6°C (Zallen et a1., 1975). Zallen et a1. (1975) concluded that the pasteurizing treatment was unnecessary based on sensory scores, total plate counts and TBA scores, which showed no significant differences between chilled loaves and chilled/pasteurized loaves. Bunch et a1. (1976) compared the sensory quality of beef-soy loaves (25% soy) prepared according to procedures in a hospital cook/chill system, after loaves were held chilled (7°C) for 24, 48, and 72 hours. A consumer panel of 31—40 college students evaluated the beef-soy loaves using a linear scale scoring system, with a 13 cm horizontal line and two endpoints (extremely undesirable to extremely desirable). Mean scores for overall acceptability were almost identical regardless of length of storage, with a mean score of 6.8 (maximum 13) which was not considered extremely desireable (Bunch et a1., 1976). Bobeng and David (1978b) compared the sensory quality of beef loaves prepared in a laboratory simulation of three foodservice systems: conventional, cook/chill and cook/freeze. Scores for both color of meat and uniformity of color were significantly different (p < 0.05) among systems. Both the cook/chill and cook/freeze loaves received lower scores for color and uniformity of color than did the conventional loaves. Flavor scores were 23 significantly lower (p < 0.01) for the cook/chill and cook/freeze loaves than for the conventional loaves. The off flavors of the cook/chill and cook/freeze loaves were attributed to autoxidation since APC values were insignificant. Zacharias (1979), reported on the sensory quality of chilled meals served to students in a school foodservice system. An initial poll of students showed that the acceptance of meals depended upon the taste, texture and appearance of the meals, with 85% of the students ranking taste as the most important criterion. A total of 23 dishes on the basis of meat, fish, eggs, vegetables, potatoes, pasta and rice were evaluated immediately after delivery in chilled conditions and during cold storage at 2°C. Two industrial plants and two large kitchens supplied a total of 80 samples, in multi-portion trays, which were evaluated on a 9 point scale for color, shape, odor, taste, consistency and texture, with 9 being optimum. Scores were divided into quality classes: scores from 9 to 7 (quality class A) corresponded to a very good — good quality, scores from 6.9-5.5 (quality class B) corresponded to a satisfactory quality, scores from 5.4 to 4 (quality class C) corresponded to a medium quality and scores from 3.9 to 1 (quality class D) corresponded to an unsatisfactory quality. After one day's storage at 2°C, 60% of the 80 samples were rated in quality class A and 37.6% in quality class B. With respect to influence of storage time, the strongest decrease was 24 nearly always noted for the attribute taste, whereas appearance and texture of the dishes changed far less. With increasing storage time (up to 10 days) the specific taste in all dishes containing a meat item became flat and increasingly masked by Spices (Zacharias, 1979). After three days of cold storage (2°C), 24.9% of all samples were rated in quality class A and 57% of samples were rated in quality class B, while after four days storage, the combined total for class A and B was 62% of total samples, which was lower than the 75% standard recommended by Zacharias (1979). Cremer (1983) compared the sensory quality of freshly prepared spaghetti to the sensory quality of spaghetti subjected to four treatments: (a) 1 hour chilled storage, (b) 24 hour chilled storage, (0) 24 hours frozen storage, and (d) 24 hour frozen storage, followed by 24 hour chilled storage. Samples of spaghetti from each of the four treatments were evaluated after reheating in an institutional microwave oven and after reheating in an institutional convection oven. Chilled samples were held at 3°:_4°C and frozen samples were held at -20° : 8°C, then thawed at 3° i_4°C. Meat sauce and spaghetti were prepared separately, combined, and cooked until the internal temperature reached 74°C. After cooking, 125 9 portions of spaghetti were weighed into plastic foam cups covered with plastic lids for reheating in the microwave oven, or into lightweight aluminum containers, covered with aluminum wrap for reheating in the convection oven. Samples were stored, 25 as previously indicated, before evaluation by an eight member trained taste panel using a linear score card, 15 cm line, word anchored at 1 and 14 cm. The overall score for spaghetti and meat sauce was highest for the freshly prepared sample, but it was not different from the sample stored in the refrigerator for one hour and heated in the convection oven (Cremer, 1983). Scores were similar for samples held one hour or 24 hours chilled, whether or not they were reheated in the convection or microwave ovens. Samples held 24 hours frozen/24 hours chilled and reheated in the microwave or convection ovens and samples held 24 hours frozen which were reheated in the convection oven were similar in quality and received the lowest scores. With respect to holding treatments, Cremer (1983) concluded that chilled samples had better sensory scores and indicated an advantage for refrigerating rather than freezing or freezing then thawing food in foodservice systems. McDaniel et a1. (1984), evaluated the effects of various packaging treatments on quality of precooked roast beef held at 4°C for up to 21 days. Boneless top round roasts weighing 1 to 1.5 kg were dry roasted to an internal temperature of 60°C, cooled for one hour and packaged by one of three methods: (a) vacuum packaging, (b) packaged in 100% C02 atmosphere, or (c) packaging in 15% C02: 30% 02: 55% N2 atmosphere. Cryovac type B C205P barrier bags were used for all treatments. At each taste panel session, panelists 26 rated six samples (two from each treatment) on a sliding hedonic scale with endpoints labeled "dislike very much to like very much". In addition, panelists were asked to complete a food action rating scale by checking one of nine statements that would most closely represent their action, ranging from 1 = “I would eat this if I was forced to" to 9 = " I would eat this every opportunity I had". Sensory scores for food action ratings for vacuum—packaged roasts were not different throughout the 21 day storage period. The roasts packaged in 100% C02 atmosphere or 15% C02; 30% 02; 55% N2 atmosphere possessed lower sensory scores at 14 and 21 days of storage as compared to values after 7 days of storage (McDaniel et a1., 1984). The 100% C02 treated roasts were significantly lower in all quality characteristics except tenderness after 14 days of storage. The gas mixture treated roasts showed lower ratings for color and flavor after 21 days of storage as compared to the 7 days values. McDaniel et a1. (1984) concluded that vacuum-packaged roasts had a slight advantage from a sensory standpoint and recommended further research to better understand the sensory quality advantages of vacuum packaged cooked beef as compared to 100% C02 - packaged cooked beef. Several conclusions can be made from the review of literature related to the sensory quality of foods prepared in cook/chill and cook/freeze foodservice systems: 3. 27 Freshly prepared foods have usually been rated higher than either chilled or frozen foods (Jakobsson and Bengtsson, 1972; Zallen et a1., 1975; Bunch et a1., 1976; Bobeng and David, 1978b; Cremer, 1983). There were no significant differences in the sensory quality of foods held chilled for 24 hours, 48 hours, or 72 hours. Zacharias (1979) reported that on the third day of chilled storage, 24.9% of all samples were rated very good-good quality and 57% of all samples were rated satisfactory. However, on the fourth day of chilled storage, only 62% of all samples were rated in the very good-good and satisfactory quality classes (Zacharias, 1979). Cremer (1983) reported no significant difference in the sensory quality of spaghetti held chilled for one hour or 24 hours. Sensory scores for chilled and frozen products were not significantly different (Zallen et a1., 1975; Bobeng and David, 1978b). However, Cremer (1983) concluded with respect to various storage treatments (24 hours frozen/24 hours chilled; 24 hours frozen; 24 housschilled) that chilled spaghetti with meat sauce had better sensory scores than frozen or frozen/chilled spaghetti. Zallen et a1., (1975) and Cremer (1983) reported 28 that frozen foods, thawed and held chilled for 24 hours, received significantly lower scores than chilled or frozen foods. In conclusion, there is agreement that freshly prepared foods have better sensory quality than the same foods processed in cook/chill or cook/freeze foodservice systems. However, with respect to storage treatment, there is not agreement among researchers on whether chilled or frozen storage is better for sensory quality of cooked foods. Packaging Materials The purpose of food packaging is to ensure that the product reaches the ultimate consumer in prime condition as visualized by the manufacturer and to satisfy the legal requirements for the stated the following 1. 2. 3. 4. There must There must quality. Acceptable It must be distribute sale of the food. Pauling (1980) requirements for a food package: be no up-take of flavors or additives. be no deterioration in microbial nutritional values must be retained. economical and safe to manufacture and along the entire length of the manufacturer—to-consumer chain. It must be capable of displaying product and brand name and other information required by law. It must not present a hazard or a problem to the ultimate user in the purchase, Opening, or 29 consumption of the product packaged. Food processing and packaging evolved to provide a steady, year round food supply of many foods. Many materials have been used for food packaging including large leaves and skins, then woven fibers, paper, pottery, glass containers, metal cans, cellulose films, cellulose acetates, and finally, a wide range of thermoplastics (Goddard, 1980). The review of packaging materials will be limited to flexible plastic films, since packaging materials used in the present study were flexible plastic films. A film is a thin flexible plastic sheeting having a thickness of 0.0254 cm or less (Sacharow and Griffin, 1970). Cellophane film was first introduced to the United States in 1924. Cellophane was manufactured from highly purified cellulose derived from bleached sulfite pulp (Sacharow and Griffin, 1970). Cellulose was then treated with sodium hydroxide solution and carbon disulfide to produce viscose. The viscose was extruded to produce a regenerated cellulose film which was washed, desulfurred, bleached, softened, dried and wound up as plain nonmoisture-proof film (Sacharow and Griffin, 1970). By incorporating various coatings and modifications, over 100 different grades of cellophane were available. Cellophanes were used in packaging baked goods, confectionery, meats, and overwraps (Sacharow and Griffin, 1970). Polymer coated varieties of cellOphane called Saran were used for oily and Greasy products. The annual usage of cellophane in food 30 packaging has steadily declined during 1965 - 1978, being replaced by polypropylene (Sacharow and Griffin, 1970). A definition of various packaging terms would be helpful in order to understand the following literature review related to packaging. Cross-linking can occur between polymer molecules to form molecular chains or it could occur between polymer molecules and other substances. Cross-linking could be achieved by irradiation with electron beams or by means of chemical cross-linking agents such as organic peroxides (Whittington, 1968). Copolymers were formed by the c0polymerization of two dissimilar molecules (Goddard, 1980). Examples of copolymers were ethylene-propylene, ethylene-butylene, ethylene-vinyl alcohol, and vinylidene chloride—vinyl chloride. Orientation is the process of stretching a hot plastic article to realign the molecular configuration, thus improving mechanical prOperties. Stretching could be applied in one direction called uniaxial orientation or could be applied in two directions, called biaxial orientation (Whittington, 1968). Upon reheating, an oriented film would shrink in the direction(s) of orientation. Orientation would be useful in shrink packaging and for improving the strength of molded or extruded articles such as pipe and fibers. Extrusion and co—extrusion are the processes by which films were manufactured. The extruder resembles a mincer into which granules are fed, heated and compressed until 31 they fuse into a melt which was forced out through a slot or die to form the film (Goddard,1980). Co-extrusion was possible by combining adaptors to extrude simultaneously two or three different c0polymers to form one film. Another means of forming multilayer films of different materials was by the process of lamination. Adhesive lamination allows the combination of incompatible materials, the incorporation of nonplastics and the manufacture of materials such as cross-laminated mono-oriented films, producing materials of extremely high strength (Goddard, 1980). Common Food Packaging Films Polyethylene has become the largest volume single film used in the flexible packaging industry. Polyethylene is a polymer of ethylene and is obtained by two processes. Low pressure or high density polyethylene (HDPE) was produced at temperatures between 60°C and 160°C and a pressure of 40 atm with alkymetal catalysts (Sacharow and Griffin, 1970). High pressure or low density polyethylene (LDPE) was obtained by exposing ethylene to temperatures between 150°C and 200°C at a pressure of about 1200 atm in the presence of traces of oxygen (Sacharow and Griffin, 1970). Polythylene is a polyolefin which along with their copolymers and related types were the predominant plastics used in packaging. Goddard (1980) defined the polyolefins as low density and high density polyethylene, polyprOpylene and polybutylene as "standard" homologues: 32 ethylene —propy1ene and ethylene — butylene as copolymers; and the ionomers which incorporate sodium or zinc metallic ions to provide cross—linking. The polyolefins have similar properties being extensible, heat sealable, and good water vapor but poor gas-barriers. Those properties can be varied by different formulations, film processing techniques and by post-film treatments such as orientation (Goddard, 1980). Other plastics used in flexible plastic films included polyvinyl chloride, polystyrene and polyamides. Polyvinyl . chloride (PVC) in its plasticised form was very flexible, highly transparent, and had pronounced blocking tendencies. Those properties along with high gas permeability made PVC suitable for meat and vegetable wrapping as well as cling or stretch wrap applications (Goddard, 1980). Groomed sheet polystyrene in thicknesses from about 200 to 2500 um was used as a wrapping and for thermo forming into trays used in food packaging. Polyamides are a range of materials made from different amino acids, characterized by a number suffix. Nylon 6,6.6 and 11 were most widely used as packaging films. Polyamides have good gas barrier performance, grease resistance and mechanical strength as well as a resistant to higher temperatures. Type 6.6 could withstand dry heat up to 250°C and had been used as a roast-in bag (Goddard, 1980). The polyamides which were not good moisture barriers, were often used as a co—extrusion with LDPE, thus protecting the nylon and providing a good barrier to moisture. Polyesters were 33 another class of polymers based on terephthalates (PETP). Polyesters have high mechanical strength and temperature stability and have barrier prOperties similar to the polyamide (Goddard, 1980). Many types of plastic manufactured with specific properties such as oxygen barrier, extensibility, heat sealing properties, resistance to oils or alkalies and resistance to temperature extremes are available for use in food packaging. It is important that foodservice professionals using cook/chill and cook/freeze production systems know some of the physical prOperties and packaging requirements for use in their operation. Chapter III MATERIALS AND METHODS Laboratory simulations of cook/chill and cook/freeze foodservice systems were used to compare the microbial and sensory qualities of foods packaged in two types of plastic casings. Foods were prepared using standardized recipes, packaged, chilled and stored chilled (-1°CiJ°C) or frozen (-7°Ci;°C) for 30 :4 days. Two types of plastic casings were used to determine if one type of casing was better to retain the microbial and sensory quality of chilled or frozen foods. Microbial quality of experimental products was based on aerobic plate counts (APC) as well as tests for specific bacterial pathOgens known to cause food poisioning: total coliforms, fecal coliforms, Escherichia coli, Salmonella, Staphylococus aureus, and Clostridium perfringens (Centers for Disease Control, 1983). Consumer and trained taste panels were used to evaluate the sensory quality of experimental products. Chili and vegetarian vegetable soup were chosen as the experimental products for this study because they were commonly used "pumpable" foods that could be prepared in the Cryovac foodservice system. The Cryovac foodservice system features preparation of large batches of soups, casseroles, sauces, and gravies which could be cooked in a steam jacketed kettle and pumped into plastic casings while the food temperature was above pasteurization temperature (282°C). 34 35 Packaginq,Materia;§ The plastic casings used in this study (C-300 and PE) were chosen to determine their relative ability to store foods chilled or frozen. The C-300 casing, which is presently being marketed for storage of chilled foods held up to 45 days, was tested to determine if frozen foods stored in C-300 casings would retain product quality as well as chilled foods stored in C—300 casings. The PE casing was more permeable to oxygen than the C-300 casing. The PE casing was compared to the C-300 casing to determine the effect of oxygen on chilled and frozen chili and soup. Oxidation reactions are often the cause of undesirable changes in foods such as oxidative rancidity of fats and oils in various foods. In addition, many vitamins, pigments, and some amino acids and proteins are oxygen sensitive (Karel, 1975). Both types of plastic casing were supplied by Cryovac Division, W.R. Grace & Co. (Duncan, SC). C—300 was a Cryovac product while the PE was a common product of competitors which was often marketed for similar uses as the C—300 casing. The C-300 casing was a five layer coextrusion of polyethylene/nylon/polyethylene with an olefin resin adhesive on each side of the nylon layer (Bieler and Howe, 1980). The laminate was cross—linked by irradiation in order to prevent delamination of the casing during the cooling or reheating process. The flexible casing permits the product to be mobile and flowable within the casing, 36 allowing a more rapid heat transfer from the product to the cooling medium. The PE casing in this study was a three layer coextrusion of polyethylene, without cross-linking. PE had previously been used for storage of frozen food in "boil—in-bag" pouches (Glew, 1973). The C-300 casing was 91 to 94 cm long and 25 cm wide. The PE casing was 85 to 87 cm long and 25 cm wide. The oxygen transmission of the C-300 casing was 20—40 cc at 23°C (m2, 24 hours, Atm.; Cryovac, 1984), compared to 2,000 cc at 23°C (m2, 24 hours, ATM) for the PE casing (Koteles, 1984). The C-300 casing could withstand temperature extremes which could range from 100°C during cooking to below 0°C in freezer storage (Cryovac, 1984). The PE casing could withstand temperatures ranging from below 0°C in freezer storage up to 90°C (Koteles, 1984). Preparation of Epperimental Prodggts The chili and vegetable soup used in this study were prepared at University Hospital in Cleveland, Ohio. Two batches (303 liters/batch) of product were prepared and shipped to Michigan State University, East Lansing, Michigan. The first batch of product was prepared on January 18, 1984 and the second batch of product was prepared on March 7, 1984. One batch of chili and one batch of vegetable soup were prepared on the same day, following standardized recipes currently used at University Hospital (Tables A-1 and A—2). *1...“ 37 Each product was prepared in a 100 gallon steamjacketed kettle (SJK; Model No. INA/2-100, Groen Div./Dover Corp., Elk Grove Village, IL). The SJK was equipped with an automatic agitator and flexible hose through which product was pumped from the kettle at the end of preparation. Product was pumped from the kettle to the pump—fill station (Groen, Pump-fill Model, Elk Grove Village, IL) and into a plastic casing, which was filled with 3.8 liters of product. The casing preclipped on one end, was filled, clip-closed, cooled and stored. The food product flow diagram is shown in Figure 1. Before preparation of the soup or chili each SJK was sanitized. The SJK was filled with a microquat/water sanitizing solution and allowed to circulate for 30 minutes while the agitator operated at speed 2 1/2. The SJK was then rinsed with hot water for 30 minutes. The sanitizing solution was pumped from the SJK through the hose in order to sanitize the hose. Chili. Total preparation time for chili (by weight: 39.54% canned tomatoes, 34.89% kidney beans, 17.23% ground beef with 20% fat, 6.89% onions, 0.57% salt, 0.57% sugar, 0.29% chili powder, and 0.02% black pepper; Appendix A-l) was approximately 5 hours. From each of two batches, 40 casings of C-300 and 40 casings of PE were filled with 3.8 liters/casing of chili. 38 Figure 1. Hospital cook/chill and cook/freeze foodservice systems: Food product flow to compare microbial and sensory qualities of cooked chili and vegetable soup stored chilled or frozen in C-300a or PEb casings. aC-300 casing was composed of a three layer laminate of polyethylene/nylon/polyethylene. bPolyethylene (PE) casing was composed of polyethylene. CFrozen products were thawed at —1C for 24 hours before samples were prepared for serial dilutions. d60—75 panelists per taste panel. eNumber of panelists per panel was 13-17 panelists. 39 FOOD PRODUCTION FLOW SOUP AND CHILI PREPARED IN 303 LITER BATCHES m HOSPITAL PUMPED INTO PLASTICI CASINGS a I b I C-SOOm CASINGS PE' CASINGS TUMBLED IN CHILLED IN MECHANICAL ICE WATER CHILIin jATH REFRIGERATED OVERNIGHT AT -2°C TO O‘C SHIPPED TO LABORATORY FOR EVALUATION (6 HOURS) 1 . CHILLED PRODUCTS PRODUCTS PUT IN STORED AT BLAST FREEZER -rz1-c :09 AT -29‘C FOR 30(24) DAYS 16 HOURS FROZEN PRODUCT STORED AT '7‘: 1‘C FOR 30(34) DAYS 1 c AEROBIC PLATE COUNTS PRODUCT REII'IEATEDETPC F j . consumes d - 73A o TASTE PANELS - TASTE PhAIIDELS (N:5 TASTE PANELS I (N=3 TASTE PANELS I 40 Vpgetable Soup. Total preparation time for vegetable soup (by weight: 63.20% water, 11.36% tomato juice, 6.29% whole, canned tomatoes, 3.21% tomato puree, 2.96% celery, 2.47% carrots, 1.97% cabbage, 1.97% onions, 0.99% baby lima beans, 0.99% corn, 0.99% peas, 0.99% potatoes, 0.49% margarine, 0.49% green beans, 0.49% long grain rice, 0.45% salt, 0.15% sugar, 0.01% marjoram and 0.01% thyme; Appendix A-2) was approximately 3 1/2 hours. From each of two batches, 40 casings of C—300 and 40 casings of PE were filled with 3.8 liters/casing of soup. gpmping Experimeptal Prodpcts Into Casings Before the chili and soup were pumped into the plastic casings, the agitator speed was increased from 2 1/2 to 4 1/2, to ensure an even mixture of ingredients in each casing. Product was pumped from the SJK through the hose attached to the bottom of the kettle to the pump-fill station. Two employees were required during the filling process. One employee held the preclipped casing under the fill valve and operated the fill valve via the foot peddle. The second employee clipped and sealed the filled casings. A casing was filled with 3.8 liters of product in 4—5 seconds and the 40 casings of one type were filled in approximately 10 minutes. Then the 40 casings of the other type (C-300 or PE) were filled. Printed "tag-type" labels identifying product and production date were attached to each casing at the closure . 3' . . .. < . ~» .. I. . 1 ~ .. - ' -- . ' '-— ,— or. . . __,,, \J'c} a 3 ' . I . . ‘. -i 3.- . -,_. u . 4‘ . 4“.) . ~_o' . . . . v . . g x‘ . . L‘ _ a‘ . V A I _ ‘ ‘ V .'~ -. - ’ l. ‘\ ~.t '. L L . .. ‘ \ . ~, \.. _; . . . . I. . , A _ . _ . . 22 ;.I . . . _ . . . . . , I, ,_ J . ‘ I” ~ 3 . < .1 _ ,‘.' . , \ I - , I - i l a g. . . i, 4, . . ' _._r J l; :4 ‘ feet 1' ‘ I ~ . ‘J ‘ _ :. ‘ ..‘.l r_______ 41 by placing the label at the neck of the casing as the clip was applied. Air was manually expressed from casings during the clipping process. The casing was grasped with the left hand above the product level while the right hand was used to pull upward on the free end of the casing. Then the casing was clipped at a point between the left and right hands. Any air remaining in the casings contracted during the cooling process. Chilling Filled Casings Filled C-300 casings which had been clipped were placed on a conveyor belt which transported the filled casings to the Washex Food Chiller, (Model No. 42124 GRN washex Machinery Corp., Wichita Falls, TX). Refrigerated water cooled to 0°-1°C, circulated throughout the chiller during the cooling process. The flexible plastic casings allowed food products to flow back and forth in the casings while being tumbled in the chilled water. This action shortened the cooling period (compared to refrigerated storage) due to a faster transfer of heat from food products to the environment (Bieler and Howe, 1980). Soup and chili in C-300 casings were cooled from 82°C to 34°C in 45 minutes. Soup and chili in PE casings were cooled in a SJK filled with ice water because the PE casing was not as strong as the C—300 casing. PE casings would not remain intact if tumbled during the cooling process in the food chiller. Chili and soup in PE casings were cooled from 82°C 42 to 34°C in 75 to 90 minutes. Once the products reached 34°C, they were removed from the chiller or ice water bath, placed in plastic racks, stacked on dollies and wheeled into the walk-in refrigerator (-2°C to 0°C) for overnight storage (Figure 1). Shipment of Prodppps On the day following preparation of chili and soup, products were placed in corrugated boxes (Stone Container Co., Newberry, SC), 20 casings per box, and loaded into a truck for transportation to Michigan State University (MSU), East Lansing, MI for microbial and sensory evaluation. No refrigeration was required during shipment of products because the outside temperature was -18°C to -12°C on January 19th and -l3°C to -7°C on March 8th. The time of shipment from Cleveland, OH to East Lansing, MI was approximately 6 hours (Figure 1). Chili and soup were unloaded at MSU; 20 bags of C—300 chili, 20 bags of PE chili, 20 bags of C-300 soup, and 20 bags of PE soup, were immediately placed in refrigerated storage (-1°C). Similar quantities of chili and soup were blast frozen (-29°C; Jamison Walkin Freezer) and placed in frozen storage (-7°C; Figure l). Prodpctpgtqpage Chili and soup packaged in C—300 and PE casings were stored chilled and frozen. Length of storage before sensory L 0dr! 1 (I II Ll .LII IIIIII 43 and microbial evaluation was 30 :4 days. Chilled storage was evaluated because it was the current storage method for C-300 casings marketed by Cryovac (Bieler and Howe, 1980). Chilled food stored at -1°C may be stored 30 to 45 days when prepared in the Cryovac system (Bieler and Howe, 1980). The storage temperature of -1°C inhibits growth of most microbes (Nickerson and Sinskey, 1972). Frozen storage was evaluated to determine if the quality of frozen foods packaged in C—300 casings would be equal to the quality of chilled foods packaged in C-300 casings. C-300 casings were previously used only for chilled storage (Andres, 1977). PE had previously been used for storage of frozen food in “boil-in-bag" pouches (Glew, 1973). The frozen storage temperature of -7°C (20°F) was chosen to accelerate deterioration of product quality in order to compare the chilled product to a frozen product normally stored 3-6 months. Glew (1973) stated that quality loss during frozen storage was due to chemical and physical changes and was dependent on storage conditions. Quality changes in frozen food after three months storage at —10°C (15°F) was roughly equivalent in changes after 6 months storage at -12°C (10°F) or to 12 months storage at -18°C (0°F) (Glew, 1973). Since little or no change in product quality would occur after 30 days storage at —18°C (0°F), the higher frozen storage temperature (-7°C) was used to 44 accelerate deterioration of product quality. Chilled products were stored in a refrigerated cubicle (Chrysler Koppin Refrigeration Co., Detroit, M1) at —1°C:1°C. Temperature of the cubicle was controlled by a Honeywell controller recorder (Model No: 15618826-4801-2- 000—061, Honeywell Instruments, Minneapolis, Minnesota). The temperature was recorded daily by a laboratory technician. The relative humidity in the cubicle was measured daily by use of an electric psychrometer (Model No. 566, Bendix Environmental Process Instruments Division, Baltimore, Maryland). Frozen products were stored in a cubicle (Chrysler Koppin Refrigeration Co., Detroit, MI) at -7°C 11°C. The temperature of the frozen cubicle was controlled and measured by the same method as for the chilled storage cubicle. Relative humidity was also recorded by the method previously described. Microbial Analyses The first purpose of the microbial analysis was to determine microbial quality of the chili and soup stored chilled or frozen in either C-300 or PE casings. A second purpose of the microbial analysis was to determine if the microbial quality of the products were equal to or if they were within acceptable limits before products were served to taste panelists. Microbial analyses of both batches of chili and soup were completed at ABC Laboratories in Gainesville, Florida, 45 under the direction of Dr. S.J. Goodfellow, and confirmatory tests on aerobic plate counts (APC) were done at MSU. At ABC Laboratories each product was analyzed for total plate count, total coliforms, fecal coliforms, Escherichia gpii, presence or absence of Salmonella, Staphylococus aureus and Clostridium perfringens. All analyses were done according to standard methods outlined in the Bacteriological Analytical Manual, by the FDA (1978). Products were shipped from MSU to ABC Laboratories for microbial analysis. One casing of product for each of four variables was coded, placed in a styrofoam cooler (Model No. Low—boy, Insul—Pack Cooler, Destin, Florida) and sent via Emery Express. Chilled samples for microbial analysis were blast frozen for shipment (24 hours before shipment). Freezing the chilled samples was recommended by Cryovac to prevent microbial growth during shipment to ABC Laboratories. Due to the shipping schedule, chili and soup samples from the first batch of products had been stored for 25 days prior to shipment to ABC Laboratories, while samples from the second batch of products had been stored for 29 days. At ABC Laboratories a 50 gram sample of product was blended with a phosphate buffer solution to prepare for serial dilutions from 10"1 to 10'4. Inoculated plates for the total plate count were incubated at 20°C. Total coliforms, fecal coliforms and E, ppLi, were determined using the Most Probable Number (MPN) technique (FDA, 46 1978). A 30 gram sample of each product was analyzed for the presence or absence of Salmonella (FDA, 1978). At the ABC Laboratories a 25 gram sample of product was analyzed for S. apreus by a direct plating method on Baird-Parker agar medium (FDA, 1978). Plates were incubated at 35°C for 45-48 hours. Plates with colonies that appeared to be S. aureus were counted. Several suspected colonies of S. aureus were subjected to the Coagulase test to confirm their identification as S._apreus (FDA, 1978). At ABC Laboratories a 25 gram sample of product was analyzed for gpperfringens by a direct plating method on Tryptose—sulfite-cycloserine (TSC) agar enriched with egg yolk emulsion (FDA, 1978). Plates were incubated at 35°C under anaerobic conditions for 20-24 hours. Suspected colonies of C. perfringens were counted and subjected to confirmation tests for C. perfringens (FDA, 1978). At MSU to prepare serial dilutions of 10"1 to 10"6 for APC's, 25 grams of product and 225 ml of sterilized 0.1% peptone water were aseptically placed in a sterile stomacher bag (Seward Medical, VAC House, London). The sample was homogenized in a stomacher (Stomacher Lab Blend Model 400, Tek Mar, Cincinnati, OH) for three minutes. Duplicate plates were placed on standard plate count agar (Fisher Scientific, Livonia, MI) using the pour plate method (Elliott et a1., 1978). The inoculated plates were incubated for 48 hours at 32°:1°C. Plates with 30 to 300 Colony Forming Units (CFU) were counted using a Standard 47 Colony Counter I (Spencer Manufacturing, Buffalo, NY). APC's were reported as the average number of colonies per gram of product. Results of APC counts were compared to guidelines for the maximum acceptable number of micro- organisms. Banwart (1981) suggested that 2,000 to 100,000 microorganisms per gram of food was the acceptable limit for APC's in frozen precooked foods. Reheating of Products Chili and soup in C-300 and PE casings were reheated in hot water to simulate production techniques which could be used in a hospital foodservice system. Products were reheated in a SJK filled with approximately 27 liters of water. The minimum recommended water temperature for reheating of product in C-300 casings was 85°C (Bieler and Howe, 1980). Two or three casings of C—300 product were placed in a SJK (Groen Manufacturer, Model No: D-S-SP, Chicago, Illinois) filled with water heated to 90°-100°C. For products in PE casings, the water temperature was originally maintained at 90°-100°C. However after several of the PE casings developed holes during the reheating process, the water temperature was lowered to 7l°-82°C to prevent holes in the PE casings. All products were reheated to an internal end temperature of 274°C. Internal end temperature of products in the casing was measured using a pocket test thermometer (Model No. 1231-14, C00per Thermometer Co., Middlefield, Conn.) which had been 48 calibrated to 11°C in boiling water (100°C). The casing was lifted from the SJK using protective rubber gloves (Model No. 9—430, Edmont Co., Coshocton, OH). The casing was placed on a stainless steel counter. The thermometer was held against the outside of the casing, near the center of the casing. The end of the casing was folded around the thermometer's stem. The thermometer was read when the needle stopped moving. If product temperature was 374°C, then the casing was returned to the SJK for additional heating. If the product temperature was 274°C, the casing was placed in a preheated thermal metal food container and transported to the testing site for the consumer or trained taste panel. Consumer Taste Panels Consumer taste panels were used to compare the quality of chilled and frozen chili and soup in C-300 and PE casings. Consumer taste panels were conducted to determine if the general public could detect differences between chilled and frozen samples in each type of casing. A pilot consumer taste panel was completed to determine the procedure for the consumer panels. The pilot consumer panel was conducted at the MSU Dairy Store located in Anthony Hall (Farm Lane, MSU, East Lansing, MI). Panelists were faculty, staff, students and visitors who had been Dairy Store customers on the day of the taste panel. The Human Subjects Committee for research at MSU did give their 49 approval for consumer taste panels conducted at MSU. The ballot for the pilot consumer taste panel was designed for a paired preference test, with no forced choice (Table A—3). The IFT Sensory Evaluation Division (1981) defined a paired preference test as one in which two samples were presented simultaneously or sequentially, with the test subject requested to express a preference. A forced choice may or may not be imposed; if it is, the subject must indicate a preference for one sample over another (IFT Sensory Evaluation Div., 1981). Since the purpose of the consumer panel was to determine if consumers had a preference for chilled or frozen products in C-300 or PE casings, panelists were not forced to state a preference. Panelists were allowed to indicate no preference on the ballot. For the pilot consumer panel only C—300 chili and soup were used. The PE casing was not used for the pilot consumer panel because Cryovac was unable to provide PE casings in time for the pilot taste panel. At the pilot consumer panel each panelist was simultaneously given two 59 m1 (2 oz.) samples of chili or soup and a ballot (Table A-3). Each sample was served in a 177 m1 (6 oz.) styrofoam cup (Dart Container Corporation, Stock No. 6J6, Mason, MI). The samples were coded with a random two digit number on the side of the cup. Each panelist was asked to indicate a preference for one sample over another or to indicate no preference. i—_____ ‘3- r . - .1 . _ v, j .. ~ , . f- A. . . --I xi. , l . ‘ . I ‘ L '1 _ , . '.:.l' , , ... . . c I. ": -;..‘4;:.l& . - .1 L . . . _. _‘ _ , L . . __e L L , , " Ci . ’ n. I! ,, ' N » 1 _ »-~‘ \ . ' I I > L: _ ' a. ’ . .1. ‘ .. ‘ , _ ,..A 4 .--). . L , l ‘ ‘ L . _ . I. _ . .. " {‘xv LL .. L L — '~‘ J L «I ,1“, 3;;- J I " -. ._ . . l 1,... . s , . , r - .’ _ ‘ ‘ 7‘ l r , --l . . . l . / .. ~./ -_ ., .. l . ; .. 'VI. . .eL. . _ .J ‘- . _ ,. v.3 1‘; \ . L . _ .. , , 1“ I V . . . L _ v . . ._ ,1 ~'-. , U254- ’L . .L ' 1 r \ .v . ‘. . \ I. 4 ’_‘ ‘4 r L . . v . ' 1 _ I I? - . 50 The consumer taste panels were conducted at various times and locations in the MSU and East Lansing community. Different locations were used in an attempt to have a sample population representative of the adult population of the United States. Consumer panels were conducted at the MSU Dairy Store, the University United Methodist Church, East Lansing; the MSU Student Union Building; and Burcham Hills Retirement Center, East Lansing. Exact dates, times and locations for consumer panels are shown in Table A-4. Four comparisons of combined main effects of storage and packaging were made during the series of consumer panels. The following four comparisons were made for both chili and soup: 1. Chilled C-300 vs. Frozen C—300 2. Chilled PE vs. Frozen PE 3. Chilled C-300 vs. Chilled PE 4. Frozen C-300 vs. Frozen PE At consumer taste panels each panelist was asked to make one comparison for chili and one comparison for soup. Sampling order for product was randomized. For each comparison the consumer was simultaneously given two 59 m1 portions of chili or soup in a 177 ml styrofoam cup coded with a two digit random number. Consumers were asked to fill out a ballot (Table A-5) giving their age, sex and indicating their response to the comparisons for chili and soup. Chili and soup for each taste panel were reheated in L»-—~ 51 the casings to 274°C by the method previously described (see Reheating Products). The casings of chili and soup were then placed in metal thermal food containers and transported to the testing site. For the consumer panel one casing of product for each comparison was poured into a stainless steel counter pan. The pans of chili and soup were placed in a preheated chafing pan partially filled with 2 liters of water. The chafing pan was heated by four to six cans (226.8g fuel/can) of solidified methane (Handy Fuel, Hotel Research Labs, Inc., Tenafly, NJ). A pocket test thermometer (Model No. 1231-14, C00per Thermometer Co., Meddlefield, Conn.) was used to measure product temperature approximately every half hour during the consumer taste panels. Product temperature was maintained at 271°C (160°F) by using additional cans of fuel. Pans of chili and soup were covered with aluminum foil to help maintain the desired product temperature. Chili and soup were ladled into styrofoam cups using a 59 ml (2 oz.) stainless steel ladle (Model No. 58620, VOllrath, Sheboygan, Wisconsin). Panelists were given the samples, a ballot, pencil, 148 ml water in a paper cup and two plastic spoons. Panelists were instructed to taste the two samples and to decide which one they preferred. Panelists were instructed to retaste the samples until a decision was reached. Panelists marked their preference or indicated no preference on the ballot and listed reasons for their decision. . i. V . . 1 - . L. l 3 ; . . ,. w. . 4 . _ ..4 l. c . . i .7 e . .. 1 . , . t z. . 1 . . 1 1 1 . \ 1 . L , . . . , . .1 I . 1 .. , .. u _ ,1 o . 3 . l . L . n . _ . . y. 1 i . u 1 1 . 1 A x . ., x. . . I.) ,, . M n .4 . l , ,. . \1 . t i. I x .1 .. y 1 1 i . . 1 . . . . x. .1 .L . .1 . . . . I . 1 .. a o . 1 1 . . , . o 52 Trained Taste Panel It was expected that the trained taste panel would detect differences that were not detected by the consumer panels. Amerine et a1. (1965) described a laboratory panel as carefully selected, highly trained and hypercritical when compared to the general consumer. Baker et a1. (1965) stated that consumer preference testing as opposed to laboratory testing was not specific and many consumers were indifferent to the characteristic being tested. Therefore, in the present study a trained taste panel was used to quantify the magnitude of differences in product quality under controlled laboratory conditions. Quantitative descriptive analysis (QDA) is a technique for characterizing the perceived sensory attributes of a product in quantitative terms (Stone et a1., 1974). The focus of QDA is on the psychophysical aSpects of perception and the application of an interval scaling technique to the problem of flavor characterization. QDA was used in a group process to develop the ballots for the trained taste panel. Two separate QDA sessions were held to deve10p the ballot for chili and to develop the ballot for soup. At the first QDA session, six panelists were asked to taste a sample of chili and write down the five or six most prominent sensory characteristics that they could distinguish. Panelists were instructed to include appearance, odor, taste, and mouth—feel characteristics (Table A-6). After each panelist had listed several sensory n.. .. I . ..1 \u .l .1 ... .. _ . 4 . . .. . . . .. 4 .2 . I. .l~ r. l. o .. . u A ~ .. _ .. _ H u . . ... . u I .J I .. 1 . ._ _ . . L . 53 characteristics, a group discussion followed. During the group discussion panelists reached a consensus to identify and quantify, in order of occurrence, the sensory properties of the chili. Panelists then developed word anchors for each sensory characteristic. The ballot for chili is shown in Table A-7. At a second QDA session, the same process was used to develop the ballot for soup (Table A—8). The scale for each sensory characteristic was a 10 cm line with marks at 1, 5, and 9 cm. The scale was word anchored at each end of the 10 cm line. Panelists made a vertical mark across the line at the point which best reflects the magnitude of his or her perceived intensity of that characteristic (Stone et a1., 1974). The panelists marks were converted to numerical scores to the nearest 0.1 cm, using a 10 cm template. Panelists were faculty, graduate students and staff in the Department of Food Science and Human Nutrition, MSU. A total of 24 different panelists participated in the three taste panels. Eight panelists attended all three sessions, eight panelists attended two sessions and eight panelists attended only one session. The actual number of panelists at each session varied from 13 for the first session, 17 for the second session and 15 for the third session. Of the 24 panelists, 16 were females aged 20-40 and eight were males aged 20-40. Taste panelists who did not attend QDA sessions were trained at a session two days prior to the first taste O h. , . 1A «I. v, i. i J l . L . J .11 . p o a . .1. , . . I .1 ..,. .A {1 I q .I I I . I A I I” z I. . . . . I4 I , . A . i . . . i 1 4 I . . . / J, 1 . . I r . 1 . 1 . J I ~ . 7. c a .. . . I . . _ I u . , . I... 1 _ .LIL 11‘ 54 panel. At the training session, panelists were given a ballot for chili and soup and were asked to rate one sample. The panelists discussed the ballot with the researcher to ensure that the panelists understood the ballot and the meaning of the word anchors for each sensory characteristic. Taste panelists who had attended QDA sessions did not require further training. The trained taste panels were conducted in the Sensory Evaluation Laboratory, in the Food Science Building at MSU. Panelists were seated in individual booths with florescent lighting. Taste panelists were asked to attend three sessions to rate the samples. At each session panelists were sequentially given four samples of chili and four samples of soup. The order of presentation of samples to panelists was randomized. Half the panelists received chili samples and half the panelists received soup samples first. A 59 ml portion of product was ladled into a 177 ml styrofoam cup (Dart Container Corporation, Stock No. 6J6, Mason, MI) and presented to panelists along with a ballot for each sample, plastic spoon, water at room temperature and a plain unleavened cracker. The samples were identified by a two digit random number on the styrofoam cup. Panelists were instructed to ask questions concerning the ballot during the taste panels to avoid confusion over descriptive terms. 5"?” 11...; ‘J- 55 Statistical Analysis: Conspmer Taste Panel To determine the statistical significance of the responses from each consumer panel, the results were plotted on the Decision Chart (Figure 2). The method for plotting the results on the chart is called sequential analysis (Bross, 1952). Sequential analysis has been used in the medical field to compare two treatments, to determine if there is a significant difference between the two treatments. The consumer ballots at each panel were numbered as they were received so the consumer responses would be plotted in the same order as they were received. For each chili or soup comparison, one treatment would be labeled "old" and one treatment would be labeled "new" in order to plot the consumer responses on the Decision Chart. According to Bross (1952) "ties" in the present study or llno difference“ responses can be dropped since each comparison by a panelist can be considered a separate "little" experiment to test the quality of the product subjected to two different treatments. If both treatments lead to the same result meaning there is “no difference" in quality, then the experiment provides no information as to which treatment is superior. Therefore, for our purposes, "no difference" responses were considered “ties" and were not included in the sequential analysis. The responses of consumer panelists from each consumer taste panel were plotted on the Decision Chart until a decision was reached. One sample of chili or soup was 56 DECISION CHART 5.I.l (a=0.l0) 25 ll I! No Use New Difference Use "O'd II O O 5 IO I5 25 30 35 35 5.I.2 (a=0.05) 30 Use "New" 25 No Difference 20 05|0I520253035 f I Figure 2. Decision Charta for the statistical significance of consumer panelists responses to comparisons of chilled and frozen chili and soup in C-300 and PE casings. aBross, I. 1952. Sequential Medical Plans. Biometrics 8:188-205. Li 57 randomly designated as the "new“ treatment while the other chili or soup sample for the comparison was designated as the "old" treatment. A decision for the "new" treatment would be indicated if the path of x's indicating consumers' responses, crossed the boundary into the clear area designated "new". A decision for the "old" treatment would be indicated if the path of x's indicating consumer responses, crossed into the clear area designated “old". When the path of x's goes up at a 45 degree angle and enters the clear area designated "no difference", then both treatments are considered equally good (Bross, 1952). Statistical Analysis: Trained Taste Panel Analysis of variance of the data was carried out using a completely randomized block design (Gill, 1978b). Data from the taste panel sessions were subjected to analysis of variance as follows: Source of variation DF Panelists 23 Storage 1 Package 1 Storage x Package 1 Residual Error 69 Total 95 The 3—way analysis of variance (ANOVA) was completed using the proqram titled Statistical Package for the Social 58 Sciences (SPSS; Nie et a1., 1975) run on a Cyber 750 CDC computer. The ANOVA was calculated for each sensory characteristic. Differences in treatment combination means were identified using the Student's t-test or the Bonferoni t-test (Gill, 1978a). For sensory characteristics with a significant (p30.05) storage x package interaction, the Bonferoni t-test was used to determine differences among treatment combination means (Gill, 1978a). If only one of the two factors (storage or packaging) was tested, then the Student's t-test was used. For sensory characteristics in which the storage x package interaction was not significant, the main-effect test from the analysis of variance was considered sufficient (Gill, 1978a). Chapter IV RESULTS Examination of the results for the microbial and sensory evaluation of chilled and frozen chili and soup packaged in C-300 and PE casings is necessary to answer the question as to whether chilled or frozen storage is better for product quality. A second question which needs to be answered is whether the C—300 casing or the PE casing is better for retention of product quality in chilled and/or frozen storage. The mean temperature and relative humidity during product storage will be examined. Results of microbial analyses of chili and soup by ABC Laboratories and MSU will be presented. Results of consumer comparisons for chili and soup will be examined as well as results of sensory evaluation by the trained taste panel. Product Storage The mean temperature and relative humidity (R.H.) for chilled and frozen chili and soup stored for 30 :4 days in C-300 and PE casings are shown in Table 1. During storage of the chilled products, the mean temperature and standard error of the mean was -l.4° :0.5°C for the first batch of products and -l.2°10.3°C for the second batch of products. The mean relative humidity was 63.0% 11.3% in the chilled storage cubicle for the first batch of products and 59 60 Table 1. Mean temperature and relative humidity (RH) for two batchesa of chili and soup stored chilled and frozen in C—300 and PE casing . Type of Storage Chilled Frogen Batch Temperature R.H. Temperature R.H. (°C) (%) (°C) (%) Batch 1 —l.4b 10.5C 63.0d rl-B -4.3b 20.9 54.1d $2.1 Batch 2 —l.2e :0.3 70.4f :1-9 --5.9e 10.3 60.2f $4.0 aFirst batch of chili and soup was produced on 01/18/84, second batch produced on 03/07/84. bN = 26 0Standard error is equal to Standard Deviation divided by the square root of N. dN = 15 EN = 23 N = 20 61 70.4% :1.9% for the second batch of chilled products. The relative humidity in the chilled storage cubicle was 10% higher during storage of the second batch of products than for the first batch. The mean temperature for frozen storage was higher during storage of the first batch of products (-4.3° :0.9°C) and fluctuated more than the mean temperature during storage of the second batch of products (—5.9° 10.30C). The relative humidity was lower during storage of the first batch of frozen products (54.1 12.1%) and varied less than the relative humidity during storage for the second batch of frozen products (60.2 34.0%). Microbial Analyses Results of microbial analyses performed by ABC Laboratories are in Table 2. Results of microbial analyses reported in Table 2 were the average of plate counts (Colony Forming Units per gram or CFU/gm) reported for both batches of chilled and frozen chili and soup. The results of microbial analysis for each batch of products are reported in Tables A-9 and A—lO. For test results reported as <3, <10, or<100 CFU/gm for each batch of product (Table A—9 and A-lO), the test results were reported in Table 2 as <3, <10, or (100 CFU/gm rather than reporting an average for those tests. The aerobic plate count (APC) was used to indicate the general microbial quality of chilled and frozen chili and 62 Table 2. ABC Laboratories: Microbial analysesa' 'b' of chilled and frozen chili and SOUP stored for 30+4 daysC in C- 300 and PE casings. Total (Aerobic) Total Fecal Product Plate Coli- Coli- g3 Salmo- _§3 Perfrin- Count forms forms Co li 'd nellae Aureusf ggpp (CPU/gm) (nan) (MPN +or— FU m FU m CHILI Chilled c-soo 1,700 9 <3 3 --h <3 <10 Frozen C-300 200 <3 -- -- -- <3 (10 ChiIIEd PE 250 <3 -- -- -- <3 <10 Frozen PE 200 <3 -- -- -- <3 <10 SOUP Chilled C-300 200 (3 -- -- -- <3 <10 Frozen C-300 25,050 <3 -- -- -- <3 (10 Chilled psi 800 <3 -- -- -- <3 <10 Frozen PE 550 <3 <3 -- -- <3 <10 aAnalyses performed by A.B.C. Research, Gainsville, Florida bAll counts were the average (N=2) of plate counts (Colony Forming Units per gram) or MPN (Most Probable Number) estimates of microorganisms from analysis of both batches of chili and soup. Results of analyses for each batch of Cproducts are reported in Tables A- 10 and A- 11. CProducts were analyzed before reheating and service to consumers. Products from the first batch of products had been stored for 25 days prior to shipment to the laboratory, while products from the second batch had been stored for 29 days prior to shipment to the Laboratory for analysis. Escherichia coli. eResults of analysis for Salmonella were reported as positive (+) or negative (—) for presence of Salmonella fin a 30 gm sample of product. Stpphylococus aureus. gClostridium perfringens. iIndicates result was negative. lChilled PE soup from the first batch of product was omitted because the shipping container was not large enough to accommodate all eight samples. 63 soup. APC's were reported as the number of Colony Forming Units (CFU) per gram and are shown in Table 2. The APC is the most commonly employed test to indicate the microbial quality of foods (Elliot et a1., 1978). As shown in Table 2, all samples of chili and soup had APC's of <100,000 CPU/gm. Longree (1972) stated that precooked foods with <100,000 CFU per gram were generally considered safe for human consumption. Frozen C-300 soup had the highest APC with 25,050 CFU/gm (Table 2). Total coliforms includes Escherichia coli, Citrobacteria freundii, Enterobacter aeroqenes, Enterobacter cloacae and Klebsiella pneumoniae (Banwart, 1981). Coliforms are common inhabitants of the intestinal tract of humans and animals, and are both fecal and nonfecal in origin. Coliforms do include psychotrophic types capable of multiplying at 3°—10°C in refrigerated foods but do not survive at freezer or pasteurization temperatures. The presence of large numbers of coliforms in cooked foods could indicate contamination of the food after cooking (Banwart, 1981). As shown in Table 2, the counts for total coliforms were low, being less than three for all samples except the chilled C—300 chili which had four. Banwart (1981) reported that the microbial specifications for precooked frozen foods purchased for the military can have a maximum total coliform count of (100 CFU/gm. So all samples tested for total coliforms were within recommended microbial limits for precooked frozen foods (Banwart, 1981). 64 As shown in Table 2, most chili and soup samples were negative when tested for fecal coliforms. The chilled C-300 chili and the frozen PE soup, had less than three CFU/gm for fecal coliforms. Fecal coliforms are relatively specific for fecal material of warm blooded animals. Fecal coliforms are destroyed by pasteurization (80°C) or normal cooking temperature and should die rapidly during freezing (Banwart, 19§;). While no standard exists for microbial counts for fecal coliforms, the count should be low or no fecal coliforms should be present. As shown in Table 2, most chili and soup samples were negative when tested for Escherichia coli, only the chilled C-300 chili had a count of less than three CFU/gm for E. coli. E. coli is the most prominent fecal coliform and inhabits the intestinal tract of man and warm—blooded animals. Some microbiologists believe that only the presence of E. coli is indicative of fecal contamination of food (Banwart, 1981). Although E. coli dies in frozen storage, in a product with gravy the death rate is lower and some E. coli may survive frozen storage for several months. The U.S. military purchase specifications for frozen foods require all food to be negative when tested for E. coli (Banwart, 1981). To summarize, all chili and soup samples were of acceptable microbial quality with respect to most probable number (MPN) estimates for microbial counts for total coliforms, fecal coliforms and E. coli. 65 As indicated in Table 2, all samples of chili and soup were negative when tested for Salmonellae. Banwart (1981) stated that lSalmonellae decline in numbers at a rate similar to E. coli in many refrigerated foods. The thermal resistance of salmonellae is also similar to the thermal resistance of E. coli. The U.S. Military purchase specifications for frozen precooked foods specifies that all samples must be negative when tested for Salmonellae. Results of tests for Staphylococcus aureus (coagulase—positive staphylococci) are shown in Table 2. All samples of chili and soup had less than three CFU/gm when tested for S. aureus. The presence of large numbers of S. aureus would be an indication of a potential health hazard due to staphylococcal enterotoxin, as well as questionable sanitation practices (Banwart, 1981). Tests for Clostridium perfringens indicated that all chili and soup samples had less than 10 CFU/gm (Table 2). Vegetative cells of C. perfringens in the growth phase are very sensitive to chilling and freezing. Tests on frozen or chilled foods often reveal only the level of C. perfringens spores which survive chilling and freezing well (Elliot et a1., 1978). In summary, all chili and soup samples were of acceptable microbial quality with respect to microbial counts for total coliforms, fecal coliforms, E. coli, Salmonellae, S. aureus and C. pgrfringes (Banwart, 1981). Microbial counts for the APC were also within the maximum 66 limit for APC's recommended at gl00,000 CPU/gm by Longree (1972). Results of the confirmatory APC's conducted at MSU are shown in Table 3. The results of the APC‘s performed at MSU are not comparable to the APC's performed at ABC Laboratory because the plates were incubated at different tempera- tures. ABC Laboratory used the FDA's method for total (aerobic) plate counts and incubated the plate at 20°C. The APC's performed at MSU were done according to the method by Elliot et a1., (1978) and were incubated at 32°C. APC‘s reported by MSU in Table 3 were the average of plate counts from both batches of chili and soup. Results for each batch are shown in Table A—ll. APC's reported by MSU were generally lower than APC's reported by ABC Laboratory, due to the difference in incubation temperature. Again, all plate counts were <100,000 CFU/gm as recommended by Longree (1972). Reheating of Products Approximate reheating times for all products are shown in Table 4. All products were reheated to an internal end point temperature (EPT) of 274°C. The frozen PE chili had the longest reheating time with 90 minutes required for the PE chili to reach an EPT of 274°C. Chili and soup in PE casings required more reheating time because the water temperature was lower than the water temperature used to reheat the chili and soup in C-300 casings. The water 67 Table 3. MSU Labs: Mean aerobic plate counts (APC)a'b'C for chiléed and frozen chili and soup stored for 30 :9 days in C-300 and PE casings. APC PRODUCT (CPU/9m) CHILI Chilled C-300 5 Frozen C-300 47 Chilled PE 150 Frozen PE 5 SOUP Chilled C-300 5 Frozen C-300 5,000 Chilled PE 25,000 Frozen PE 50 aAnalysis performed by MSU using the method by Elliot et a1., (1978). bAPC's reported are the average (N=2) of plate counts from analysis of both batches of chili and soup. CSamples were analyzed prior to reheating for sensory evaluation. dChili and soup from the first batch of products had been stored for 25 days before microbial samples were taken, while chili and soup from the second batch had been stored for 24 days prior to analysis. “'4'7'? . . : ., «who .. ._ _ .13 away - I}; - .:«.. . ._ ....u_-., é;;§--‘.'.u.- _ _, . .h (“.1 ' “.I-IC'JHZCI -. .. . .r . A _ .,__ 'l ‘Ie . - - l A ', r. . v .2» _ _ _l e ' - - . . - , . \ ‘ . . . , i - - .. , . . . o - .. 1 ”I . . ' “ ' 1“! .L .'. 'fl - _ _ . - . _ . .. . _- v. I V t. u EMU?- ...‘.:.lf) 2211'.) 68 Table 4. Approximate reheating ti esa in ho waterb'c for chilled and frozen chili and soup in C—300 and PE casings. Product Chili Soup_ Packaging Chilled Frozen Chilled Frozen (min.) (min.) (min.) (min.) C-300 50 75 35 40 PE 60 90 40 45 aTime reported was the time usually required for the product to reach an internal endpoint temperature of 274°C. Exact times were not recorded when reheating products because products were reheated to the specified temperature. bFor C-300 casings, water temperature in steam jacketed kettle (SJK) was 9o°—100°C. CFor PE casings, water temperature in the SJK was 71°-82°C. dEach casing contained 3.8 liters of product. 69 temperature for reheating products in PE casings was maintained at 7l°-82°C to prevent leaks in the casings. The water temperature for reheating products in C-300 casings was maintained at 90°—100°C because that was the temperature recommended for rapid reheating of products in C-300 casings (Bieler and Howe, 1980). Consumer Taste Panels Consumer taste panels were conducted to determine if the general public could detect differences in sensory quality of chilled and frozen chili and soup in each type of casing. Several taste panels were conducted at the MSU Dairy Store, located on the MSU campus. Taste panels were also conducted at two locations in East Lansing. See Table A-4 for a complete listing of panel locations, comparisons and main effect studied. Results from the consumer panel at the MSU Union Building (2/20/84) were not included because the temperature of the soup at the time of service to panelists had drapped from 260°C to 344°C. The soup was ladeled into styrofoam cups approximately 20 minutes prior to service and placed in an insulated hot cart. Apparently the temperature of the soup decreased while it was in the hot cart. The temperature of the soup at the point of service to panelists should have been 260°C (Cardello and Maller, 1982). Cardello and Maller (1982) reported on consumer acceptability of water, selected beverages and foods as a function of serving temperature. For solid and 70 semi—solid foods that are normally served hot, acceptability increased monotonically with increasing temperature (Cardello and Maller, 1982). Since the preferred serving temperature for soup was 60°C, the actual serving temperature could have affected the outcome of the soup comparison for the panel at the MSU Union Building. The chili comparison for the taste panel at the MSU Union Building could not be evaluated because a small leak had developed in the PE casing during reheating. water from the reheating medium had leaked into the casing, but was not discovered until the PE casing was cut Open and the chili was poured into a pan. So results of the taste panel conducted at the MSU Union Building were not included. Results of the consumer panel at Burcham Hills Retirement Center (2/21/84) for chili were included but results of the soup comparison at the Burcham Hills consumer panel were excluded. Although the number of panelists at the Burcham Hills panel (36 panelists) was less than the 50-75 panelists needed to qualify as a consumer panel (IFT Sensory Evaluation Division, 1981), a decision was reached for the chili comparison. Results of the soup comparison were omitted because there were not enough panelists to reach a decision. Responses of consumer panelists for each chili or soup comparison were plotted on the Decision Chart using the method previously described (Bross, 1952). A summary of the results of consumer panel comparisons for chilled and frozen ‘ W‘IF 71 chili and soup are shown in Table 5. Results of the sequential analysis of consumer responses for each chili and soup comparison were plotted on Decision Charts and are shown in Figures A-l to A-7. Whether or not consumers preferred chilled or frozen product depended on which product was tested and in what casing the product was packaged. Also whether or not consumers preferred product in C-300 or PE casings depended on which product was tested and whether the product had been stored chilled or frozen. Chili Comparisons. Whether consumers preferred chilled or frozen chili depended on in which casing the chili was packaged. Chilled C-300 chili was preferred when compared to frozen C-300 chili for the consumer panel located at the University Methodist Church on 02/19/84 (See Table A-4). The comparison of chilled C—300 chili and frozen C-300 chili was repeated during the consumer panel located at the MSU Dairy Store on 02/21/84. At the second consumer panel, panelists did not detect a difference between chilled and frozen C-300 chili. The comparison of chilled and frozen C-300 chili was repeated because the researcher felt that the results of the first consumer comparison for chilled C-300 and frozen C-300 chili was only marginally in favor of the chilled C-300. This comparison was of primary importance and the researcher wanted to be sure that a consumer preference for chilled C-300 chili existed. . . , l v .) z A .. A e . \ I . _ . . . y .. r . . . .. A. t . .. . . l 4 . _ . . . {. u . . . l . n . . , . _ . _ A . . . 1 . a . o . . r . .. H . n x .. . . . L 1 . . . , . . w... . . . _ e . m . , . . . N . N _ . » . w r .. , . . , 1 . v . 1 . . . , . . , . . . . . 1 . . e y. . < J 1 v ( n .. . . . o J .. . . z . r :3 _ r . . .1 , . . _ . . . c l . 1 , . :1. ‘ |l 72 Table 5. Consumer taste panel results for comparisons of chilled and frozen chili and soup packaged in C-300 and PE casings. Main Comparison Effect Result§E_ Studied Chili Soup Chilled C-300 Chilled C-300 vs. Storage Preferred or No Frozen C—300 No Difference Difference Chilled PE vs. Storage Frozen PE Frozen PE Frozen PE Preferred Preferred Chilled C-300 vs. Packaging No Chilled C-300 Chilled PE Difference Preferred Frozen C—300 vs. Packaging No Frozen C-300 Frozen PE Difference Preferred aStatistically significant difference, pg_0.05. 73 However, results of the second consumer taste panel did not agree with results for the first consumer taste panel. The Decision Chart for the chilled C-300 vs. frozen C-300 comparisons are shown in Figure A-l. In comparing chilled and frozen chili in PE casings, the frozen PE was preferred (Table 5). Several consumer panelists commented on the ballot that the chilled PE chili had an off-flavor, which was difficult to describe. The flavor of the chilled PE chili was described as old, flat, or refrigerated. The flavor of the frozen PE chili was described as spicier, more flavorful, zestier, more tomato flavor than the chilled PE chili and had no off-flavor or aftertaste. Consumers preferred the frozen PE chili. The Decision Chart for the chilled PE chili vs. frozen PE comparison is shown in Figure A-2. For both chili comparisons in which packaging was the main effect studied, consumers could not detect a difference between chili samples in either comparison (See Table 5). In comparing chilled C-300 chili and chilled PE chili, no difference was detected. In comparing frozen C-300 chili and frozen PE chili, again no difference was detected by consumer panelists. Decision Charts for chili comparisons in which packaging was the main effect studied are shown in Figures A-3 and A—4. In summary, whether consumers preferred chilled or frozen chili in C—300 or PE casings depended on which main effect (storage or packaging) was studied. With respect to .1 . 74 storage for chili in C-300 casings, consumers preferred the chilled C—300 chili or they could not detect a significant difference between chilled and frozen chili in C—300 casings. With respect to storage for chili in PE casings, frozen PE chili was preferred. With respect to packaging, consumers did not detect differences in sensory quality of chilled or frozen chili in either casing. Soup Comparisons. Whether consumers preferred chilled or frozen soup depended on in which casing the soup was packaged (Table 5). In comparing chilled C—300 soup and frozen C-300 soup, no difference in sensory quality was detected by consumers. In comparing chilled PE soup and frozen PE soup, the frozen PE soup was preferred. The Decision Charts for the soup comparisons in which storage was the main effect studied are shown in Figures A-5 and A_60 For the soup comparisons in which packaging was the main effect studied, chilled or frozen soup in C-300 casings was preferred over chilled or frozen soup in PE casings. For soup, there was a package effect with consumers showing a preference for chilled and frozen soup packaged in C-300 casings (See Table 5). The Decision Charts for the soup comparisons in which packaging was the main effect studied are shown in Figure A-7. As shown in Table 5, consumers did not detect differences between chilled and frozen soup in C-300 75 casings. This comparison was evaluated by two consumer taste panels (See Table A-4 for date and location of panels). The consumer panel at the Dairy Store on 02/17/84, compared chilled C-300 soup and frozen C-300 soup. Consumers at that panel did not detect a significant difference between the two soup samples. This comparison was repeated at the Dairy Store again on 04/05/84. The second consumer panel also did not detect a significant difference in sensory quality between chilled and frozen soup in C-300 casings. The comparison was repeated because this comparison was of primary importance to the research. The researcher wanted to be sure that consumers did not detect significant differences between chilled and frozen soup in C—300 casings. The Decision Charts are shown in Figure A-5 for the chilled vs. frozen soup in C-300 casing comparisons. In comparing chilled and frozen soup in PE casings, the frozen PE soup was preferred. The Decision Chart for this comparison is shown in Figure A-6. Consumer panelists preferred the frozen PE soup because it had more flavorthan the chilled PE soup. Several panelists described the flavor of the frozen PE soup as richer or fuller than the flavor of the chilled PE soup. The flavor of the chilled PE soup was described as flat, bland, watered down and it had an unpleasant aftertaste. One panelist described the taste as a plastic taste, while another panelist described the taste of the chilled PE soup as having a clinical taste. The 76 frozen PE soup was preferred over the chilled PE soup. For both soup comparisons in which packaging was the main effect studied, soup in the C-300 casing was preferred over soup in the PE casing for chilled and frozen storage. In comparing chilled C-300 soup and chilled PE soup, consumers preferred the flavor of the chilled C-300 soup (Figure A—7). The chilled PE soup again was described as having a metallic taste, bitter taste, tasted flat or was more watery than the chilled C-300 soup. In comparing frozen soup in C-300 and PE casings, the C-300 soup was preferred. The flavor of the frozen C—300 soup was described as stronger, spicier, richer and the vegetables were crisper. Again the flavor of the frozen soup in PE casing was described as having an unpleasant aftertaste, a metallic taste, was too bland or tasted more watery than the frozen C-300 soup. In summary, consumer's preference for chilled or frozen soup was dependent on in which casing the soup was packaged. Consumers did not have a preference for chilled or frozen soup in C-300 casings. Consumers did have a preference for frozen soup in PE casings. For both soup comparisons in which packaging was the main effect studied, consumers preferred soup in C-300 casing whether the soup was chilled or frozen. The reason most often given by consumers for their preference for soup in C—300 casings was due to an unpleasant aftertaste for soup in PE casings. 77 Trained Taste Panel A trained taste panel was used to evaluate the sensory quality of chilled and frozen chili and soup in C-300 and PE casings. It was expected that the trained taste panel would detect differences between samples that were not detected by the consumer panels. Panelists evaluated each sample of chili and soup for several sensory characteristics using a 10 cm line with marks at l, 5 and 9 cm. The ballots for chili and soup are shown in Tables A-8 and A-9. In general the trained taste panel detected few significant differences in the sensory quality of chilled or frozen chili in C-300 or PE casings. Results of the analysis of variance (ANOVA) for the chili samples showed only three sensory characteristics which had a significant storage x package interaction. There was no significant difference among chili samples for overall acceptability. The trained taste panel did detect significant differences among chilled and frozen soup in C-300 or PE casings for several sensory characteristics. Results of the ANOVA for the soup samples showed several sensory characteristics which had a significant storage x package interaction in the ANOVA. Frozen soup in PE casing was rated significantly higher with respect to overall acceptability than frozen soup in C—300 casing. A closer examination of the results provided below specifies which significant differences among chili and soup samples were detected by the trained taste panel. 78 Sensory Evaluation of Chili. Results of the trained taste panel evaluation of chilled and frozen C—300 and PE chili are shown in Table 6. Mean scores, standard error of the treatment combination means (VMSE7H), statistical significance of main effects and the storage x package interaction are shown in Table 6. As shown in Table 6, storage was statistically significant for aroma. Since the packaging effect was not significant and the storage x package interaction was not significant for aroma, the four treatment combination means (i.e., chilled C-300 chili, frozen C-300 chili, chilled PE chili, and frozen PE chili) need not be compared. A comparison of the average of the means for chilled chili (5.15) versus the average of the means for the frozen chili (4.80) showed a significant difference (p<0.10) with the chilled chili rated higher than the frozen chili with respect to aroma. For integrity of beans, the packaging effect was significant (p <0.001). As shown in Table 6, the storage effect and the storage x package interaction were not significant for integrity of beans. The average mean score for chili in PE Casings was significantly higher (7.35 versus 5.75) than the average mean score for chili in C-300 casings. So trained taste panelists preferred the integrity of beans in the chili packaged in PE casings regardless of which storage method was used. Three sensory characteristics had a statistically ooooamflooam no: u do .Hoo.ovo .... mumflaoccm ugmfim can mcoflmmwm osu Ham popcobum mhmflaocmm unmflo mC muoom Essfiumo H OH mum£3 eoHIo m0 mamom .coflmmom wso popcouum .Ho.ovo ... .mo.ovo .. .oa.ovo . Cmmm2> 0 ma mcwwE .O.B mo uOuuw Gumvcmumv o n popcouum mumwawccm “swam .mcoflmmom moms» .mcoflum>ummno men: .mconmom mossy mo ccozo .... o: o: sa.o n.o m.o o.o m.o suaaaoeuooooa Haeoooo we .... m: o: eH.o o.e s.e a.» o.e ouoeuoooma me «a: me u: hfioo «1w m.o w.w n.w mwoSMmMOuU m: .... on m: mm.o m.m m.m m.m ..m uo>oam sumo: . .... me me Hm.o ~.o m.m m.m ~.o oosdao steam .. .... we we .H.o H.. 0.. n.. o.m moccaoamm «a «a... cast .2. N~.o N6 m4. 9.6 «.5 oudunuomaos we .... .... m: -.o ..e e.m m.n o.m women no spasmoueH m: .... we do H~.o e.. ..o m.. ... oosuxoa o: .... m: . m«.o 9.. 5.. H.m ~.m neon. m: .... on ma mm.o H.. m.» m.» ~.o oceanowmna use “ovooaaoeoo Amsmeamoxotm lavomouoom coo: .o.e we oomuo mm oomuo oooeflmsum o ooze so“: am a>oz< mo oooom zmeomm mmmmmmu ooHamHmmaoememo cu upcmum moéosm .mmcflmmo mm was oomlo :fl HHHSO :mN0um cam wmaaflco mo huflamsm whomcmm now mosam> m mo oocmoflwficmflm was memos .o.e mo uOuno pum©CCum .monoom some A.U.Bv coeumcflnsoo uswsummne undocmm ounce pocwcua .m wanna mm 80 significant storage x package interaction, temperature, spiciness, and beany flavor; a further comparison of differences between means was done using the Bonferroni t-test (Gill, 1978a). The comparison of means for temperature, spiciness and beany flavor are shown in Table 7. With respect to temperature, there was a significant difference between mean scores for chilled PE and frozen PE chili or frozen C~300 and frozen PE chili. The frozen PE chili rated lower in both cases. A comparison of mean scores for spiciness showed a significant difference between chilled C—300 chili and chilled PE chili with a higher mean score for the chilled PE chili (Table 7). A comparison of mean scores for beany flavor showed no statistically significant differences between mean scores (p (0.05). In summary, the trained taste panel detected few significant differences in the sensory quality of chilled or frozen chili in C—300 or PE casings. Results of the analysis of variance for the chili samples showed only three sensory characteristics which had a significant storage x package interaction. A comparison of mean scores for those characteristics having a significant storage x package interaction (temperature, spiciness, beany flavor) showed that frozen PE chili was rated lower than either chilled PE chili or frozen C-300 chili. Spiciness was rated significantly higher for chilled PE chili than for chilled 81 Table 7. Trained Taste Panels: comparison of treatment combination mean scores + for sensory evaluation of chilled and frozen chili packaged in C-300 and PE casings. Storage Characteristic Packaging Chilled Frozen Temperature# C—300 7;§Aa 7.3Ha PE 8.0Aa 6.2B***b*** Spiciness# C—3oo 3.8Aa 4.0Aa PE 4.3Ab* 4.1Aa Beany Flavor# C—300 6.2Aa 5.9Aa PE 5.5Aa 6.2Aa +Comparison of mean scores for sensory characteristics which had a significant storage x package interaction in the ANOVA. Two means in the same row were significantly different if they have different uppercase superscripts. Two means in the same column for a given characteristic were significantly different if they have different lower case superscripts. *Indicates level of significance: *p30.10 **p30.05, ***pgp.01, ****pgp.001. #Comparison of means by Bonferroni t-test (Gill, 1978a). 82 C—300 chili. A comparison of mean scores for beany flavor showed no significant differences between mean scores. In general, the trained taste panel did not have a preference for chilled or frozen chili in either casing. Sensory Evalgation of Soup. Results of the sensory evaluation of chilled and frozen soup in C—300 and PE casings are in Table 8. All sensory characteristics for the soup samples except aroma and greasiness showed a signifi- cant storage x package interaction in the three way ANOVA. Sensory scores for aroma and greasiness will be discussed first because the storage x package interaction was not significant in the ANOVA for aroma and greasiness. A comparison of mean scores for all sensory characteristics for soup except aroma and greasiness are in Table 9. For aroma the packaging effect was significant in the ANOVA but storage and the storage x package interaction were not significant (Table 8). The mean for aroma for soup in C-300 casings was 4.95 compared to the mean for soup in PE casings of 4.55. Results of this comparison of means using the student's t-test (Gill, 1978a) showed a significant difference with the soup in C-300 casings rated significantly higher (p<0.10) than soup in PE casings. For greasiness the packaging effect was significant in the ANOVA but storage and the storage x package interaction were not significant (Table 8). The mean score for soup in C-300 casings was 5.15 and the average mean score for soup oeooaoaemam oo: u we .Hee.qwo «... .Ho.me««. .mo.me*« .oH.me« :\mms ou Hcsvo mw memos sou may no sound puwcccum :ssflumo ww ca muons O nu e OHIO NO ”HMOWQ .aofiwwow oco mumwaosmm named .msowmmom oz» couscous m couscous umaaoccm unmfim .m20wwmow moan» Haw popaouuc mumflaocmm unmfio .msofluc>uomno av": .chmeom oouau mo ccozm c... coco a: o o~.o o.u m.m ~.m o.m auuuwnouoouo4 Huoua>o .e :2. a: c an... o... no mo «.0 3330...: a: coca a... a: ha... 6.. .....m u.m N.m auccaoaouo cc. «to. coca c... ~«.o ... ... ... n.m nounouomo> no cuauuoa cc. .. a... co co uu.o 5.. 5.. n.n 5.. Auoum no uo>oah «a. «co. c... a... oné n.» a6 7m «.6 Ousuluoaaon. «a. a... .c a: . wu.o n.n N.. m.. a.. nounuuomy> no auwumousu ... a... c a: .«.o a.» n.. H.m n.m uoanauomw> no uoaoo c... «a... a: cc «.7: ..o . a6 N.m . «.0 nuoum no ”—0.30 a «cc. a: a: o~.o n.n m.m H.n o.m Juana no honouaaucoo . acoun.mo c «cc. a: an n«.o H.. m.. ... 9.. aowuauomom no acumen a: a... c a: ou.o ... H.m 5.. a.. . «sand . 111nm. oomuu (tum comic and «ovuoaaoeee Assessmexoee .csomauoum one: .o.a one umaaqmu ooauuuuoooeueao . a a o as a e < oz< . wwemmuww .IIllllllmmmmmmwllllllllll .mmcflmco mm Muaacav anomcom so u c. msom cancuomo> concum new coaafino mo 6 ocmow mwsam> m mo acmowmficmwm can some .u.a mo neuuo pucpcmum . canoe .mouoom some A.U.Bv :oflumcfinaoo ucosumoua undoccm ounce panache m mm Table 9. Trained Taste Panels: comparison of treatment combination mean scores for sensory evaluation of chilled and frozen vegetable soup packaged in C-300 and PE casinqs. Storage Characteristic Packaging Chilled Frozen Degree of C-300 4.0Aa 4.5Aa Separation# PE 4.6Aa 4.1Aa of Broth Consi tency of C-3oo 3.6Bb 3.3Bb Brothi PE 3.1Bb 3.5Bb Color of B th@ C— .2C 5.9C "° .3.“ :2. ..4D**** Color of C-300 5.5e 4.7e Vegetables$ PE 5.1e 6.of**** Integrity f C-300 4.99 4.29 Vegetablesg PE 4.89 5.5h** # _ Ii Ii Temperature CPEOO gZin*** g:§Jj*** Fl # __ . KK 4. Kk avor of Broth CPgOO §,;K1*** 4.;L**k Mm N***m Texture of C—300 5.9 4.4 Vegetables# PE 6.6Mm 6.4Mfl*** Aftertaste$ C—300 6.9o 6.8°*** PE 6.90 7.69 Overall C-300 5.6Q 5.3Q**** Acceptability@ PE 5.1Q 6.0R +Comparison of mean scores for sensory characteristics which had a significant storage x package interaction in the ANOVA. superscripts were significantly different. same column for a given characteristic were significantly different if they have different lower case superscripts. Indicates level of significance: *p 30.10, **p $0.05, *** p $0.01, Two means in the same row with different uppercase Two means in the Comparison of means in same row and same column by Bonferroni t—test, m=4 (Gill, 1978a). @Comparison only of means in the same row using Student t—test (Gill, 1978a). $Comparison only of means in the same column using Student t-test (Gill, 1978a). 85 in PE casings was 5.8, a significant difference (p <0.001) for packaging. Apparently, the soup in C-300 casings appeared greasier than the soup in PE casings. As shown in Table 9, chilled PE soup had significantly lower mean scores than frozen PE soup for several characteristics: color of broth, temperature, flavor of broth, and overall acceptability. In the C—300 casing there were no significant differences between mean scores for chilled and frozen soup, except in the case of texture of vegetables, where the mean score was significantly higher for the chilled C—300 soup. In comparing chilled C-300 soup and chilled PE soup, there were significant differences between mean scores for temperature and flavor of broth. The mean score for the chilled C-300 soup was higher in both cases. In comparing frozen C-300 and frozen PE soup, there were significant differences in mean scores for these characteristics: color of vegetables, integrity of vegetables, temperature, texture of vegetables, and aftertaste. For these characteristics the mean score for frozen PE soup was significantly higher than the mean score for the frozen C—300 soup, except for temperature where the mean score was higher for the frozen C-300 soup. In comparing chilled and frozen soup in PE casings, the frozen PE soup received higher mean scores for several characteristics. 80 frozen storage would be better than chilled storage for soup in PE casings. In comparing 86 chilled and frozen soup in C-300 casings, few differences between mean scores would indicate that either chilled or frozen storage could be used for soup in C~300 casings, although the scores for chilled soup were consistently a bit higher than for frozen soup in C-300 casings. For chilled storage, there were only two characteristics which had significant differences between mean scores for C—300 and PE soup. Either casing may be nearly equally suited for chilled storage of soup. For frozen storage of soup in C-300 and PE casings, soup in PE casings had higher mean scores for several characteristics. For frozen storage of soup, the PE casing appears to retain product quality better than frozen soup in C-300 casings. Chapter V DISCUSSION Further examination of the results for the microbial and sensory evaluation of chilled and frozen chili and soup packaged in C-300 and PE casings is necessary to answer the question as to whether chilled or frozen storage is better for product quality. A second question which needs to be answered is whether the C-300 casing or the PE casing is better for retention of product quality in chilled and/or frozen storage. Several factors which could have affected the results of the microbial analyses or the sensory evaluation need to be examined. Factors to be discussed include microbial analysis, reheating method, and the age and sex of consumer \ panelists. Results of the consumer taste panels and trained taste panel will be examined to determine if any relationship exists between consumer and trained taste panel results. Product Storage: Temperature Chilled storage was evaluated because it was the current storage method for C-300 casings marketed by Cryovac (Bieler and Howe (1980). Chilled food stored at -1° t_l°C may be stored 30 to 45 days when prepared in the Cryovac system (Bieler and Howe, 1980). Frozen storage was evaluated to determine if the quality of frozen foods 87 88 packaged in C-300 casings would be equal to the quality of chilled foods packaged in C-300 casings. The frozen storage temperature of —7°C (20°F) was chosen to accelerate deterioration of product quality in order to compare the chilled product to a frozen product normally stored 3-6 months. Glew (1973) stated that quality loss during frozen storage was due to chemical and physical changes and was dependent on storage conditions. Since little or no change in product quality would occur after 30 days storage at -18°C (0°F), the higher frozen storage temperature (-7°C) was used to accelerate deterioration of product quality. Fluctuations in storage temperature, eSpecially for frozen foods, can contribute to deterioration of frozen foods (Kramer, 1979). Kramer (1979) stated that losses in \ sensory quality and vitamins increased with time—temperature conditions of storage, and were greater under fluctuating (i5°C) temperatures conditions than at constant (11°C) temperature conditions. In frozen storage of foods, fluctuations in temperature are inevitable due to the operation of the freezer (Griswold et a1., 1979). Fluctuations in the freezer temperature called cycling are due to the operation of the compressor which only operates when the freezer compartment reaches a set temperature and stops when the temperature drops to a set temperature (Griswold et a1., 1979). The effects of temperature fluctuations should be minimized in well wrapped packages (Griswold et a1., 1979). .. . x . , M r . z . . _ r . . . , _ . t .. _ . . .. . /( t il— L . / .... _ J y. .. e . .1. . . _ 1. M r . r ; . r V . yr. . .Q _ 89 As shown in Table l, the fluctuations in storage temperature for both chilled and frozen products was greater during storage of products from batch one, with the frozen storage temperature fluctuating more than the chilled storage temperature. Not only does the temperature fluctuation affect product quality, but the time-temperature relationship also affects product quality. Kramer (1979) stated that there is an exponential relationship between temperature and time to produce a given degree of quality change for most products. Generally, for every 5°C increase in storage temperature, the rate of quality loss increased 2-2 1/2 times (Kramer, 1979). Tressler (1968) stated that in the case of precooked foods solidly frozen, changes in quality were due to chemical reactions. The rate of those chemical reactions increased 2 1/2 times when temperature increased 10°C (18°F). Although.researchers agree to the general principle that an increased storage temperature decreases optimum storage time, there is not agreement on the exact decrease in storage time for a given increase in storage temperature. Tressler (1968) stated that temperature fluctuations between —5°C and +5°C did not significantly affect product quality when compared to the same product stored at a constant temperature of 0°C for the same length of storage. Based on the mean storage temperatures shown in Table l, the temperature fluctuations were not large enough to greatly affect the sensory quality of the chilled and frozen chili and soup. 90 Microbial Analyses In general, results of the microbial analyses indicated that all chili and soup samples were within acceptable microbial limits for the specific organisms tested. (See Table 2 and Table 3) The aerobic plate count (APC) was used as an indicator of the microbial safety of chilled and frozen chili and soup. Longree (1972) recommended a limit of $100,000 CFU/gm for APC's for precooked foods. The U.S. Military purchase specifications for precooked frozen foods also has a microbial limit of $100,000 CFU/gm for APC's. Results of the APC's performed by ABC Laboratory (Table 2) are not comparable with APC's performed by the researcher at MSU (Table 3). ABC Laboratory incubated the plates at 20°C while the plates at MSU were incubated at 32°C. Elliott et a1., (1978) stated that aerobic plates made from foods spoiled in the refrigerator may yield colony counts one or more log cycles higher when incubated at 4°—28°C than when incubated at 35°~37°C. A closer examination of the APC's for each batch of chili and soup shows that for the first batch of products the APC's for the frozen soup (Table A—9) were higher than the APC's for the chilled soup. For the second batch of chili and soup (Table A—lO) the chilled soup had higher APC's than the frozen soup. Since many microorganisms do not survive freezing temperatures, it was expected that APC's from frozen samples would be lower. Banwart (1981) 91 stated that coliforms, fecal coliforms, and g;_pgrfringgp§ vegetative cells in the growth phase, usually die during freezing. However, spores of C. perfringens are known to survive quite well during chilling and freezing (Elliott et a1., 1978). Although E. coli dies in frozen storage, in a product with gravy the death rate is lower and some E. coli may survive frozen storage for several months (Banwart, 1981). Since the counts for C.pperf£inqens and E. coli were low (Table A-9), it is unlikely that the higher APC's for frozen soup were due to these organisms. The higher plate count for the frozen soup could be due to lack of temperature control at some point during product preparation, cooling, storage and shipment to the laboratory for analysis. Since only one casing of product for each variable was analyzed for microbial counts, there could have been variation within the batch. The result of the APC for frozen soup from the first batch of products (Table A—9) could also be due to laboratory error during testing. How do the microbial results in the present study compare with microbial results from other studies? Several studies in which researchers assessed the microbial quality of foods prepared in a cook/chill or cook/freeze foodservice system will be discussed (Nicholanco and Matthews, 1978; Bebeng and David, 1978b; Cremer et a1., 1985). Nicholanco and Matthews (1978) evaluated the microbial quality of beef stew in a hospital cook/chill foodservice system. APC's were highest during chilled storage and were 92 lowest immediately after preparation and after reheating in microwave ovens. Mean APC's during chilled storage ranged from 8.4 x 104 CFU/gm after three hours storage to 14.5 x 104 CFU/gm after 19 hours storage. The microbial counts reported by Nicholanco and Matthews (1978) are higher than APC's reported in the present study. Nicholanco and Matthews (1978) cooled the beef stew in a walk—in refrigerator at 5°-10°C. The temperature of the beef stew did not reach g7°C until after nine hours. The longer cooling time could have contributed to the higher plate counts. Bobeng and David (1978b) assessed the quality of beef loaves prepared in a laboratory simulation of conventional, cook/chill and cook/freeze foodservice systems. APC values for beef loaves in all three systems were $350 CFU/gm after baking, during storage, thawing and after reheating in a microwave. Bobeng and David (1978b) concluded that adherence to the time-temperature standards in the Hazzard Analysis Critical Control Point (HACCP) model was sufficient to ensure microbial safety of foods served in these foodservice systems. Although APC's for the chilled beef loaves reported by Bobeng and David (1978b) were in agreement with APC's in the present study, it should be noted that the chilled storage was only 24 hours for beef loaves compared to 30 t_4 days in the present study. Cremer et a1., (1985) assessed the microbial quality of chicken and noodles prepared in a hospital cook/chill foodservice system which was similar to the hospital 93 cook/chill foodservice system simulated in the present study. The chicken and noodles was prepared in a steam jacketed kettle equipped with a mechanical stirrer, pumped hot from the kettle into plastic casings, (574°C) clip-closed and chilled in an air agitated water both at 3.4 :_l.l°C. After cooling, the product was stored in a walk-in refrigerator at 1.3 :_0.9°C for 30 days. The casing was a cross—linked, coextruded multi-layer transparent film with an oxygen transmission rate of 20-100 cc per square cm per 24 hours at 22.8°C (Cremer et a1., 1985). Samples of chicken and noodles were analyzed for total mes0phi1ic aerobic plate count (incubated at 35°C for 48 hours), total psychrotrophic aerobic plate counts (incubated at 7°C for 10 days), coliforms and staphylococci. Cremer et a1., (1985) reported that the mean total plate counts increased in numbers as the refrigerated storage time increased from zero to four weeks (24 days) but were all within acceptable microbial limits. All meSOphilic and psychrotrophic APC's were 3500 CFU/gm after four weeks storage (Cremer et a1., 1985). For the present study, the APC's for chilled or frozen chili and soup were all $100,000 CFU/gm as recommended by Longree (1972). Several researchers have evaluated the mircobial quality of foods prepared in cook/chill, cook/freeze or conventional foodservice systems (Bunch et a1., 1976; Zallen et a1., 1975; Nicholanco and Matthews, 1978; Bobeng and David, 1978b; Cremer et a1., 1985). Food 94 products evaluated were prepared, cooked, and stored using various methods, packaging, storage temperatures, and length of storage. Food products were of acceptable microbial quality having $100,000 CFU/gm (Bunch et a1., 1976; Zallen et a1., 1975; Nicholanco and Matthews, 1978; Bobeng and David, 1978b; Cremer et a1., 1985). The chilled and frozen chili and soup in the present study were also of acceptable microbial quality at the point of service to the consumer. Reheating of_grodggts Casings of chili and soup were reheated in a steam jacketed kettle (SJK) filled with approximately 27 liters of water. Chili and soup in C—300 casings were reheated in water at 90°~lOO°C because Bieler and Howe (1980) recommended a minimum water temperature of 85°C for the rapid reheating of products in C-300 casings. However, product in the PE casings were reheated in a steam jacketed kettle with water at 71°~82°C. When the researcher attempted to reheat chili in PE casings in water at 90°-100°C, the PE casings developed large holes, so the water temperature was lowered to 7l°-82°C. The frozen chili in PE casings required the longest reheating time (90 minutes) due to the lower water temperature. The researcher attempted to reheat all chili and soup samples to the same endpoint temperature 274°C. However, due to the difference in water temperatures, some chili and soup samples in C~300 casings were 285°C when they were removed from the SJK. 95 Also, it was difficult to control the temperature of the water in the SJK because the temperature was adjusted by closing or opening the steam valve to the SJK. Use of a thermostatically controlled water bath to reheat the chili and soup could have resulted in a more uniform end point temperature for all samples. Product temperature was measured with a pocket test thermometer approximately every half hour during taste panels, but was not recorded. Product temperature was generally maintained at 71°C (160°F) during taste panels. The temperature of some pans of chili and soup were 271°C (160°F) or 360°C (140°F) when product temperature was determined. The temperature of the frozen PE chili was usually 74°C when removed from the SJK, while the temperature of the frozen C—300 chili was usually 77°C. Large differences in product temperature during taste panels could have affected the outcome of consumer preference panels or trained taste panel results. It was easier to maintain product temperature at the consumer panels because only four products (two pans of chili and two pans of soup) were used. During trained taste panels, there were eight pans (four chili, four soup) and it was more difficult to keep all products at the same temperature. Results of the trained taste panel did show a significant storage x package interaction with respect to temperature for chili and soup. A comparison of mean scores with respect to temperature (Table 7) showed a significant 96 difference between mean scores. Frozen PE chili was rated significantly lower than frozen C-300 chili or chilled PE chili. The difference in water temperature for reheating chili in C-300 and PE casings could be responsible for frozen PE chili being rated lower. A comparison of mean scores with reSpect to temperature for soup also showed significant differences between means (Table 9). The chilled PE soup was rated significantly lower than either chilled C—300 soup or frozen PE soup. Frozen C-300 soup was rated significantly higher than frozen PE soup but was not significantly different than the mean score for chilled C—300 soup with respect to temperature. Again, differences in water temperature during reheating of products could have contributed to differences in product temperatures during the trained taste panel. Sensory Quality of Chilled and Frqgen Chili and Soup The sensory quality of chilled and frozen chili and soup, packaged in C-300 and PE casings, and stored for 30‘: 4 days was evaluated by consumer and trained taste panels. Consumer taste panels were conducted to determine if the general public could detect differences in chili and soup samples in the present study. It was expected that consumers might have a preference for chili or soup subjected to a given storage and packaging treatment but that consumers would not be able to quantify any differences detected. Amerine et a1., (1965) stated that in general _i_. _. . _ - \ .'= ., .. ,( I... 1‘ .' V _ I .‘ I~ L. r .. fl ‘1' .1 . . ..-‘. _ J". . J.- .. ‘ . I . , . J‘ _.- ‘ - . - .5. _'.. -' '-. . '11-. » . ', f_- ...' ”300112 “ ' - i .. . 3 ik . E- l‘i'I' 2 .-_ .- n . l' H}: ' ' ‘ ‘ ‘ 1 ""11 ~ J." ' o 4' ' . _. ‘ '_ )1". 'fiX'II' D" . . _ .. ._. ._I\ - .‘ L" _ .-. '.'i.i.’J|'.11aLD-I - -' 2.} ::...;i’ _ [ST-3555 . H ' h’ - 9.. . . ., - .1 :- 511:5'1Jc2fik:.. . - _. _.' 1 - I u.) 13:; Stuntin- 97 consumer acceptance testing as opposed to laboratory testing, the direction of preference was not specific and that many consumers were indifferent to the characteristics being tested. Consumers might agree with laboratory panel findings in direction but usually do not agree in magnitude (Amerine et a1., 1965). In the present study it was expected that the trained taste panel would detect differences that were not detected by consumers. Therefore, the trained taste panel was used to quantify the magnitude of differences in product quality under controlled laboratory conditions. Consumer Taste Pane1_ Whether consumer panelists preferred chilled or frozen product depended on which product was tested and in what casing the product was packaged. Whether consumers preferred chilled or frozen chili in C-300 or PE casings depended on which main effect (storage or packaging) was studied. With respect to storage condition for chili in C—300 casings, consumer panelists preferred chilled C—300 chili at one panel but had no preference for chilled or frozen chili in C-300 casings at another panel (Table 5). With respect to storage condition for chili in PE casings, panelists preferred frozen chili in PE casings. For chili comparisons in which packaging was the main effect studied (Table 5) consumer panelists had no preference for chilled samples in either casing and had no preference for frozen 98 samples in either casing. Whether consumers preferred chilled or frozen soup also depended on in which casing the soup was packaged (Table 5). Consumers did not have a preference for chilled or frozen soup in C-300 casings, but did prefer frozen soup in PE casings. For soup comparisons in which packaging was the main effect studied, consumers preferred soup packaged in C-300 casings for both chilled and frozen storage (Table 5). Were there other factors which could have affected the outcome of consumer panels such as the sex or age of panelists. How do results for the consumer panels in the present study compare to previously reported works by other researchers. How do results from the consumer panel for the present study compare to results for the trained taste panel. Chili Co parisons. For the chili comparison in which ‘—____—1 storage was the main effect studied, consumers preferred chilled chili in C—300 casings at one panel (2/19/84, University Methodist Church), but did not have a preference for chilled or frozen C-300 chili at a second panel (2/21/84, Dairy Store). The difference in the conclusion of the two taste panels could be due to differences in length of hot holding of the chili samples during the taste panels. The panel at University Methodist Church (Table A-4) took place after Sunday morning services, so a larger .. .-_=. r15: aslqulsa .': ;- .. .. -- ,: tit-.1 3:. taillsi-uIC-i: 151:2;er -,.\.:_ *- ._;.-_>. gust-3‘: .':;1 '-.J ...“. ..o hafmsqab -~ '_'.;31- _ ;_. .-,' _. . .i. - . (I; 31615..” . .-:..-.-,(. ._ ' ”.‘::r; .. £11,5-;- 1:102 119.3013 10 ,n_ ..z- 5.. - _ . . . . ..:-:~1:.-';:: :1'; ‘32.. ; . . .‘ :H‘u-. .~-:E.;. toil. dish adj _ . : _ -, - . .x ‘ . . a 016": hi .(3 c-5n1) . .. 1. . . _ -. .‘ - .. ... -. .. “1'33": ' _ -, a. 4‘“ a ,u ~ -- .3. r;;na;c:.:p> cmoojso 13 .': . . _-. 5;. .1 _. ,. .:..:i-‘-a.r.i-:.s£ssq ' ~~ - ‘~ '- .- - .- -.-E.-,,o:.-. .'Jn‘aasiq . . _ ‘ _ ‘ ‘ . .‘ . . ‘ .‘._',. _ . ~- . ~ - - ... . . . . . \ .. . ..' a. .11.}15'.‘t3'.71 .. . . . f v ..L“.'J.'u - _' f l . _ , ,- ' _ ‘ . .....,, .\.. - . . .‘ -..w ‘-'i:"---"" . . . .. . . . . ..r c ..-—-;,;._,-.;. ' ‘. I. . . -. _gSMJJAL ’ -‘ -- _, . f ..: ~ . ~ '_ :\jfi‘§\_31‘ —»'~'~ l"- - ' - I .. f :..'. : -. ‘ _ g ' 4 t .'.."..‘3., U5: adj ‘ ‘ I‘ . .. - 5 '. ,___:., 1. ‘JI'..."..-'...0.'.'i 30: 3.0 , . _ ._ _ .. ‘ . . 9191159 ‘3‘ - \--‘ ‘— ._ 1.1. f ; .__ 2 ~.: 3.-.; 1" (It. 99 number of panelists (n=78) tasted the chili in a shorter time period. For the panel at the MSU Dairy Store on 2/21/84, a longer time period of four hours was required to obtain enough responses from panelists to reach a decision as panelists responses were plotted on the Decision Chart (Figure A-l). If product quality did deteriorate during hot holding, then it may have been more difficult to detect any differences that did exist between chili samples. In comparing chilled and frozen chili in PE casings consumer panelists preferred frozen PE (Figure A-2). Based on comments from consumers, written on the ballots for this comparison, it appeared that panelists preferred the taste of the frozen PE chili. Several panelists mentioned that the chilled PE chili had an off-flavor. The flavor of the chilled PE chili was described as old, flat or refrigerated. The off-flavor of the chilled PE chili could be due to oxidation reactions, such as oxidative rancidity of any fats or oils in the chili (Karel, 1975). The PE casing was more permeable to oxygen than the C—300 casing. The oxygen transmission rate of the PE casing was 2,000 cc at 23°C (m2, 24 hours, Atm) (Koteles, 1984) compared to 20-40 cc at 23°C (m2, 24 hours, Atm) for the C-300 casing (Cryovac, 1984). The flavor of the frozen PE chili was described as spicier, more flavorful, zestier and more tomato flavor than the chilled PE chili. Changes in quality of the chili in PE casings due to oxidation reactions would occur at a slower rate in the frozen chili, since the rate 100 of deterioration is dependent on temperature (Glew, 1973). For both comparisons in which packaging was the main effect studied, consumer panelists detected no significant differences due to packaging. Consumer panelists had no preference for chili in either casing for chilled storage or for frozen storage (Table 5). If there were differences in quality of chili samples due to packaging, they were not detected by consumer panelists. Zacharias (1979) used school children to compare the sensory quality of 23 dishes, including meat entrees, vegetables, potato, pasta and salads, held chilled at 2°C for from one to ten days. Zacharias (1979) reported that with increasing storage time the specific taste in all dishes containing a meat item became flat and increasingly marked by spices. Zacharias (1979) concluded that sensory quality rating of chilled meals evaluated by school children was most dependent upon the taste, texture and appearance. When asked to indicate these three attributes in order of priority 85% of all students noted taste as the most important (Zacharias, 1979). In the present study, consumer panelists also often mentioned the taste of the product when stating their preference for a specific chili sample. It is interesting that consumer panelists detected an off flavor in chilled PE chili when it was compared to frozen PE chili, but panelists did not detect an off flavor in chilled PE chili when it was compared to chilled C—300 chili. 101 Sggp_ggmpari§gn§. For soup comparisons in which storage was the main effect consumers did not detect a significant difference in chilled and frozen samples for soup in C-300 casings. With respect to storage for soup in PE casings, consumers preferred frozen PE soup (Table 5). The comparison for chilled versus frozen soup in C-300 casings was made by consumers at two separate taste panels (Table A-4) and both panels reached the same conclusion (Figure A~5). Based on results of the present study it appears that consumer acceptability of chilled soup in C-300 casings is as good as for frozen soup in C-300 casings. With respect to storage condition for soup in PE casings, consumers preferred the frozen PE soup. Consumers described the flavor of chilled PE soup as flat, bland, watered down, and it had an unpleasant aftertaste. For both soup comparisons in which packaging was the main effect studied, soup in the C-300 casing was preferred over soup in PE casings for both chilled and frozen soup. Once again panelists mentioned flavor as the reason for their product preference. Again the flavor of the chilled PE soup was described as having a metallic taste, bitter taste, tasted flat or was more watery than the chilled C—300 soup. The flavor of the frozen PE soup was also described as having an unpleasant aftertaste. The flavor of the chilled C-300 soup and the frozen C-300 soup were described as stronger, spicier, fuller and richer. Zacharias (1979) reported that cooked vegetables held 102 chilled at 2°C from one to ten days, had a flavor described as flat, acid, pungent and stale after ten days chilled storage. The chilled foods were rated by school children who had rated taste as the most important attribute in acceptance of a food product (Zacharias, 1979). A comparison of consumer panel results for the present study to results from previous work is difficult since few researchers have used consumer panels to compare foods prepared in cook/chill and cook/freeze foodservice systems. Other factors which could affect the outcome of consumer responses should be considered. The sex or age of consumer panelists could have affected the responses of panelists if males or females preferred either chili or soup. Age could affect consumer panel results if taste sensitivity is related to age and if consumer panels were unbalanced with respect to age of panelist. For the present study, consumer panelists responses for chili comparisons, classified by sex. are shown in Table A-12. Consumer responses for soup comparisons classified by sex are shown in Table A-13. The age and sex of consumer panelists by panel location is shown in Table A-l4. As shown in Table A—14, the majority of taste panelists for panels one, three, four, and five were in the 20-29 and 30-39 age group. At those panels, few panelists were 520 years old or 260 years old. For taste panel number two, there were a larger number of panelists in the <20 age group. Panel two was conducted after a Sunday morning 103 service at University Methodist Church and had more children than any of the other panels. Also at panel two, there were more panelists in the 260 age category. There is not agreement among researchers on the effect of age on taste sensitivity. In researching taste thresholds, Aubek (1959) in Amerine, et a1., (1965) reported no significant impairment of taste sensitivity prior to 60 years of age. Above age 60, there were significant decreases in sensitivity to salty, sour, sweet, and bitter. No sex differences were observed for the decline in taste threshold sensitivity (Aubek in Amerine, et. a1., 1965). Cooper et a1., (1959) in Amerine et a1., (1965), found that curves for development and decline started in the late 508 and affected sour less than the other tastes. For the present study, since the majority of consumer panelists were in the 20—50 year age group and taste sensi— tivity is not affected until 260 years of age, the re- searcher concluded that age did not affect consumer panelists. Sex of panelists could have an effect on the outcome of the consumer panels if the panels were not composed of equal members of males and females. Panels one and four had about the same number of males and females, while panels two and five had about 10 more males than females. Panel three had twice as many males as females. So with the exception of panel three, the consumer panels were composed of approximately equal numbers of males and females. Bradley 104 et a1., (1954) in Amerine et a1., (1965) reported that the preference ratings of women as a group did not differ significantly from those of men. Women's responses extended over a greater range than those of men, but individual women tended to be more consistent in their ratings than individual men (Bradley et a1., 1954, in Amerine et a1., 1965). In studies of canned fruit conducted in California, female consumers were more definite in their preferences than males, who gave less homOgeneous responses as a group and preferred sweeter samples than did women (Bradley et a1., 1954, in Amerine et a1., 1965). In the present study more males than females indicated no preference responses for chili and soup comparisons (Table A-13 and Table A—l4). This would seem to support Bradley‘s findings that female consumers were more definite in their preferences than males (Bradley et a1., 1954 in Amerine et a1., 1965). However, Bell (1956) in Amerine et a1., (1965) reported that preferences for breads of different formulation were unaffected by age and sex. Amerine et a1., (1965) concluded that due to incomplete and inconclusive investigations, it was difficult to predict preference behavior of specific age group or of males versus females for most food products. An examination of consumer panelist responses classified by sex (Table A—12 and A—13) shows that most of the consumer panels had approximately the same number of male and female panelists. However, the consumer panel for — 105 the chilled C—300 soup versus chilled PE soup comparison at the MSU Dairy Store (2/21/84) had twice as many males as females. Responses of consumer panelists from the MSU Dairy Store on 2/21/84 classified by sex of panelists and product preference are in Table 10. The observed frequencies and expected values for each cell are shown. Using the test p c statistic q = ELZ[(Oij—Eij)2/Eij] the hypothesis that the 333% effects of the row citerion are independent of effects of the column criterion was tested (Gill, 1978a). The calculated test statistic of 0.287 was less than the critical value 1:20.05,1 = 3.841 (Gill, 1978b). Since the hypothesis of independence for the effects of sex of panelists on the product preference was not rejected, it was concluded that sex of panelists did not affect the outcome of the consumer taste panel at the MSU Dairy Store on 2/21/84. In summary, consumer's preference for a given storage condition depended on the type of casing in which the product was packaged. For the chilled C-300 versus frozen C-300 comparison for both chili and soup, consumers in general did not detect significant differences in sensory quality. It would appear that the C—300 casing retains product quality as well during frozen storage as it does during chilled storage. With respect to storage for products packaged in PE casings, consumers preferred frozen chili and soup in PE casings. The chilled chili and soup in PE casings had an aftertaste which consumers did not like. _ 106 Table 10. Observed frequency and expecteg valuesa for consumer taste panel responses to the consumer comparison of chilled C—300 chili versus chilled PE chili. Product Sex of Panelists Chili Chili Total C—300 PE Male 31 10 41 (30.2) (10.8) Female 11 5 16 (11.8) ( 4.2) Total 42 15 57 aNumbers in parenthesis () were the expected values calculated as the product of the row total x the column total, divided by the total number of observations (Gill, b1978a). Location of consumer taste panel, MSU Dairy Store, 2/21/84. ...—..q—n—M. effect no pre packag prefer qualii great the s compa prodr both concl 'pum 0-3 H a: dif: chi chi Sig tr: re: no to di 107 For both comparisons in which packaging was the main effect and chili was the product being tested, consumers had no preference for product in one casing. With respect to packaging conditions for soup comparisons, consumers preferred soup in C—300 casings. Difference in product quality due to packaging for chili comparisons might not be great enough for consumers to detect, or might be masked by the spice in the chili itself. For both packaging comparisons for soup, consumers detected differences in product quality and preferred the soup in C—300 casings for both chilled and frozen storage. Therefore, the researcher concludes that consumers would accept chilled or frozen "pumpable" foods packaged in C—300 casings. Trained Taste Panel The trained taste panel detected few significant differences in the sensory quality of chilled or frozen chili in C—300 or PE casings. Results of the ANOVA for the chili samples showed only three sensory characteristics (temperature, spiciness, and beany flavor) which had a significant storage x package interaction. Results of the trained panel in the present study are in agreement with results from the consumer panels which also in general did not have a strong preference for one chili sample compared to another chili sample. The trained taste panel did detect significant differences among chilled and frozen soup samples in C-300 L» or PE c (Table among 5 C-300 no pre the tr sensor casing easie: Sing; for t pack: inte: waSj scor com; betv madt Sig int be: can in ca 108 or PE casings for several sensory characteristics (Table 8). Consumer panelists did not have preferences among soup samples except for in the comparison for chilled C—300 soup versus frozen C—300 soup, in which consumers had no preference (Table 5). Results of the consumer panel and the trained taste panel indicate that the difference in sensory quality of chilled and frozen soup in C—300 or PE casings were greater in soup than for chili samples or were easier to detect. Sepsory Evaluatiop of Chili. Aroma was significant (p<0.05) for the storage effect in the ANOVA for chili. Since the packaging effect was not significant, nor was the interaction significant, it is not known which chili sample was preferred by panelists with respect to aroma. The mean score for aroma for the frozen PE chili was lowest, but a comparison of means showed no significant differences between mean scores (Table 6). Very few consumer panelists made comments on the aroma of chili samples. For integrity of beans, the packaging effect was significant (p<0.001), but the storage effect and interaction of main effects was not significant (Table 6). A comparison of mean scores with respect to integrity of beans showed a significant advantage for chili in PE casings. The beans in the PE chili might have been more intact than beans in the C-300 chili because chili in PE casings were cooled in an ice water bath while chili in —_—, c-300 casi Methods, ( mentioned However, chilled o the chill Thre significe spicines: of means respect due to d chili i! C-300 c: the tem Wi PE‘chil Chilled of a c] Consumc it was consum it was indivj influe Chili 109 C-300 casings were tumbled in a mechanical chiller (see Methods, Chilling Filled Casings). Few COnsumer panelists mentioned the preference for a given sample of chili. However, a few consumer panelists did mention that the chilled or frozen PE chili was more chunky or thicker than the chilled or froZen C—300 chili. Three sensory characteristics had a statistically significant storage x package interaction; temperature, spiciness, and beany flavor (Table 6). A further comparison of means showed a significantly lower mean score with respect to temperature for frozen PE chili. This could be due to differences in water temperature during reheating the chili in C—300 and PE casings. The temperature of chili in C-300 casings was 74°-77°C when removed from the SJK, while the temperature of the chili in PE casings was usually 74°C. With respect to spiciness, mean score for the chilled PE chili was significantly higher than the mean score for chilled C—300 chili. Consumers often listed the spiciness of a chili sample as the reason for their preference. Some consumer panelists preferred a specific chili sample because it was spicier than the other chili sample. However, other consumer panelists preferred a specific chili sample because it was less spicy than the other chili sample. For individual panelists their response to spiciness could be influenced by their preference for a mild chili or a spicier chili. Although beany flavor had a significant —‘—‘ , storag of me: The 51 0.31; other agree stror casir inc01 pane stud Beng obta at - bee: Stu. and qua bee es; the at di ch Cr 110 storage x package interaction (Table 6) a further comparison of means showed no significant differences between means. The standard error of the mean scores for beany flavor was 0.31 and was larger than the standard error for several other sensory characteristics (Table 6). So there was not agreement among panelists with respect to beany flavor. In general, the trained taste panel did not have a strong preference for chilled or frozen chili in either casing. The results of the trained taste panel were inconclusive as to which storage and packaging combination panelists preferred for chili. How do trained taste panel results for the present study compare to previously reported works? Jakobsson and Bengtsson (1972) reported a clear flavor advantage was obtained for frozen precooked beef after two months storage at —20°C over the pasteurized, refrigerated, cooked sliced beef stored at +3°C for only a few days. In the present study taste panelists did not detect differences in chilled and frozen chili in C-300 and PE casings. Changes in quality of the cooked ground beef in the chili could have been masked by the sauce, spices or other ingredients, especially in the chili. Kossovitsas et a1. (1973) reported that after 15 days chilled storage at 2°C and frozen storage at —23°C, taste panelists could not detect significant differences in appearance, flavor and consistency between chilled and frozen samples of Chicken a la King, Codfish in Cream Sauce and Broccoli with Cheese Sauce. However at 30 days 01 interh B (p<0.0 loaves cook/f were 1 cook/r measu three of th (1978 froze Othel prec: the- sens in t agre Prof fro: st; 000 dif Cha 111 days of storage the chilled samples were acceptable but interior to fresh samples (Kossovitsas et a1., 1973). Bobeng and David (1978b) found significant differences (p<0.01) for flavor scores among systems in comparing beef loaves prepared in the conventional, cook/chill and cook/freeze production systems. The conventional loaves were rated significantly higher, with no difference between cook/chill and cook/freeze samples. The microbial quality measured by total aerobic plate counts was excellent for all three systems (Bobeng and David, 1978b). Thus, the results of the present study were in agreement with Bobeng and David (1978b) with few significant differences between chilled and frozen chili. Although freshly prepared products were included by other researchers in comparisons of chilled versus frozen precooked food, freshly prepared products were not used in the present study because the purpose was to compare the sensory and microbial quality of chilled and frozen products in two types of plastic casings. Also there is general agreement among other researches that freshly prepared products received higher sensory scores than chilled or frozen products (Jakobsson and Bengtsson, 1972; Kossovitsas et a1., 1973; Zallen et a1., 1975; Bobeng and David, 1978b). Cremer et a1., (1985) concluded that for chicken and noodles stored for four weeks at l.3° i0.9°C, no significant differences in general acceptability occurred and no flavor changes indicated the effectiveness of the plastic storage bags in overall range f General my the 501 signif (Table signif froze: where chill panel agree C-30( for < Cons1 Off qual lows cha: bro con pan Cor 112 bags in preserving food quality. The mean scores for overall acceptability of chili samples in the present study range from 6.3 to 6.6 on a scale from one to ten. Generally, chili samples were in moderately good quality. Sensory Evaluation of Soup. All sensory characteristics for the soup samples except for aroma and greasiness showed a significant storage x package interaction in the ANOVA (Table 8). For soup in C-300 casings there were few significant differences between mean scores for chilled and frozen soup, except in the case of texture of vegetables, where the mean score was significantly higher for the chilled C-300 soup (Table 9). Results of the trained taste panel sensory evaluation for soup in C—300 casings are in agreement with the consumer panel comparison for soup in C—300 casings. Consumer panelists did not have a preference for chilled or frozen soup in C—300 casings (Table 5). Consumer and trained taste panelists concluded that chilled or frozen soup in C—300 casings were of equal sensory quality. As shown in Table 9, chilled PE soup had significantly lower mean scores than frozen PE soup for several sensory characteristics; color of broth, temperature, flavor of broth and overall acceptability. Again, results of the consumer panels are in agreement with the trained taste panel for comparisons of chilled and frozen PE soup. Consumer panelists also preferred frozen soup over chilled soup in mention undesir an unpl Tt signifj sensor} vegetal accept; agreem prefer Consum compar taste conclr differ that ( al. p seleC' the g the s of ch Crite COnSu Prefe taste Pr6f< 113 soup in PE casings (Table 5). Consumer panelists often mentioned the flavor of the chilled PE soup as being undesirable. The flavor of chilled PE soup was described as an unpleasant aftertaste, flat and old. The trained taste panel rated frozen PE soup significantly higher than frozen C—300 soup for several sensory characteristics: color of vegetables, integrity of vegetables, texture of vegetables, aftertaste and overall acceptability. The trained taste panel results are not in agreement with the consumer panel results because consumers preferred frozen C-300 soup when compared to frozen PE soup. Consumer panelists also preferred chilled C—300 soup when compared to chilled PE soup (Table 5). Perhaps the trained taste panel and consumer taste panels did not reach the same conclusion because the trained panelists detected additional differences between frozen C—300 soup and frozen PE soup that were not detected by the consumer panel. Amerine et a1. (1965), described a laboratory panel as carefully selected, highly trained and hypercritical when compared to the general consumer. Zacharias (1979) reported that 85% of the school children participating in the sensory evaluation of chilled meals, rated taste as the most important criterion in sensory quality of a food product. Perhaps the consumer panelists in the present study based their preference for frozen C—300 soup or frozen PE soup on the taste of the two samples. The trained taste panelists preferred the flavor of broth in the frozen PE soup or chilled C- the chill: The and PE ca texture < temperatl could al vegetabl TrE PE casil casings afterta panelis a batct batch 4 paneli produc paneli with 1 02/17‘ and r gnali H). Show SOup C-BC ll4 chilled C-300 soup when compared to the flavor or broth in the chilled PE soup (Table 9). The difference in chilling methods for soup in C—300 and PE casings could have an effect on the integrity or texture of the vegetables. The difference in water temperature in reheating the soup in C—300 and PE casings could also have an effect on the integrity or texture of vegetables. Trained panelists rated aftertaste for frozen soup in PE casings significantly higher than frozen soup in C—300 casings. Apparently the trained panelists did not find the aftertaste of the PE soup as objectionable as did consumer panelists. However, it should be noted that there could be a batch effect. Consumers compared soups from the first batch of products produced on 1/18/84 while trained panelists rated soup samples from the second batch of products produced on 03/07/84 (Table A—4). However, consumer panelists compared chilled and frozen soup in C—300 casings with product from the first batch of soup at the panel on 02/17/84 and from the second batch of products on 4/10/84 and reached the same conclusion, no difference in sensory quality of chilled or frozen soup in C—300 casings (Figure A—4). In summary, mean scores for soup in C-300 casings showed only one significant difference for chilled or frozen soup in C-300 casings: texture of vegetables, with chilled C-300 soup scoring higher than frozen C-300 soup. For soup _—— in PE cas higher me PE casing scores fr C—300 501 panel, P 115 in PE casings several sensory characteristics received higher mean scores for frozen soup than for chilled soup in PE casings. Frozen PE soup also received higher sensory scores for several sensory characteristics than did frozen C-300 soup (Table 9). Based on results of the trained taste panel, PE casings could be used for frozen storage of soup. Mil soup in Ni4 pasteur in less lower . microb produc produc any mi rehea‘ foods prodr Pack: note< coul. 000k 139$ difl Chi pro Chapter VI CONCLUSIONS AND RECOMMENDATIONS Microbial quality of chilled and frozen chili and soup in C—300 and PE casings was of excellent quality after 30 i 4 days storage. Packaging products at above pasteurization temperatures (282°C), cooling product to 37°C in less than two hours and storing chilled product at a lower chilled temperature of —lo 21°C, contributed to the microbial safety of kettle-cooked foods. Reheating the product in the casings prevented recontamination of the product. Reheating the products to 274°C also ensured that any microorganisms presents would be killed during reheating. Results of the present study suggest that for precooked foods packaged in PE casings, frozen storage retained product quality better than chilled storage. For products packaged in C—300 casings few significant differences were noted for chilled versus frozen storage. The C-300 casing could be used for product storage in either a cook/chill or cook/freeze foodservice system. Recommendations for Future Rgsearch Consumer and trained panelists detected few significant differences between chili samples. Due to the nature of the chili with the meat, sauce and strong spices, changes in product quality could be difficult to detect. Perhaps 116 testing to deter packagi Pr tempera while 1 900-10 a long Differ casing tempe: the s soup. be de tempe mini: were tast sigr C-3t tem med for ten ch: du. 117 testing a product with a milder flavor would make it easier to detect changes in sensory quality due to storage or packaging. Products in PE casings were reheated in water at a temperature of 7l°-82°C, to prevent holes in the PE casings, while products in C—300 casings were reheated in water at 90°—100°C. The difference in water temperature resulted in a longer heating time for chili and soup in PE casings. Differences in sensory quality of products in C—300 and PE casings could be due to differences in the time and temperature of the reheating process. It was difficult to control the water temperature in the steam jacketed kettles used for reheating the chili and soup. Use of a thermostatically controlled water bath may be desirable to have greater control over the final product temperature. All casings of product were reheated to a minimum temperature of 74C, but some products in casings were at 77°-82°C when removed from the kettle. The trained taste panel did rate the temperature of frozen PE chili significantly lower than either chilled PE chili or frozen C-300 chili. This could be due to a difference in product temperature when removing the casings from the reheating medium. Or there could be a difference in heat retention for chili in PE casings. The trained taste panel rated the temperature of chilled PE soup significantly lower than chilled C-300 soup or frozen PE soup. Again this could be due to the difference in water temperature for reheating soup 1] T' and PE qualit oxidat values detect 1 with 1 Traint highe diffe consu hot-h consu four for ( chili Coulr Glew of f reas C0nv Cons woul PGrj 118 soup in C-300 and PE casings. The difference in oxygen permeability between the C-300 and PE casing could have resulted in differences in product quality due to oxidative rancidity. A physical measure of oxidative rancidity could be determined by using TBA values. TBA values could then be related to off—flavors detected by the consumer taste panelists. The results of the trained taste panel did not agree with the results of the consumer taste panel (Table 5). Trained taste panelists rated frozen PE soup significantly higher than frozen C—300 soup. One reason for the difference in results of the trained taste panel and consumer panel evaluation of soup could be due to the longer hot—holding period during the consumer taste panels. The consumer panels were conducted over a period of three to four hours, while the trained taste panels were conducted for one to one—and-one—half hours. Sensory quality of both chili samples or both soup samples at a given consumer panel could have deteriorated due to the long hot-holding period. Glew and Armstrong (1981) cited the long hot—holding period of foods in the conventional foodservice system as one reason for poor sensory quality of foods served in the conventional foodservice system. Perhaps conducting consumer panels at locations where more consumer panelists would be available to taste the samples in a shorter time period would be useful in future research. The PE casing is cheaper than the C-300 casing and .,.—_ ‘ could be results soup in chilled from an practic operati casing storag the ch author cook/c V 119 could be used in a cook/freeze foodservice system. Based on results of the consumer panels, chilled chili or chilled soup in PE casings would not be preferred when compared to chilled chili or soup in C—300 casings (Table 5). However, from an operational standpoint the PE casings is not very practical for a cook/chill or cook/freeze foodservice operation. The PE casing was not as strong as the C—300 casing and required more careful handling during cooling, storage and reheating. Products in PE casings, especially the chili, required much longer reheating times. Thus, the author recommends the C-300 casing for use in either cook/chill or cook/freeze foodservice systems. APPENDIX Table A'3 Ingredie Beef, 9; 20% fat‘ onions, chili pl Tomatoe salt black 1 Bean, Sugar, Total 3In t and m 120 Standardized recipe for chili con carne used at University Hospital, Cleveland, Ohio. Table A-1. Expected Yield: 303 liters Total Weight: 394.92 kg Chili Con Carne Ingredients % Weight Instructions Beef, ground, 1. Place ground beef, 20% fata 17.23 onion and chili onions, minced 6.89 powder in steam chili powder 0.29 kettle and saute until browned (approxi- mately 90 minutes). Tomatoes, canned 39.54 2. Add tomatoes, salt 0.57 salt and pepper to black pepper 0.02 meat and cook about 60 minutes (crush tomatoes by hand before adding). Bean, kidney 34.89 3. Drain kidney beans. Discard the liquid. Sugar, granulated 0.57 4. Add kidney beans and sugar to above Total 100.00 mixture. Cook for 2 hours. Skim off any grease that rises to the top of kettle before serving. 5In the first batch of chili, 40% of ground beef was frozen and was initially browned for 45 minutes. Table Ingre water tomai toma‘ toma‘ carr onio baby pota marg wax gree salt suga thyn marj cele cabt cor] pea: tic: tot; n 30 re bIr Table A-2. Ingredients water 121 Standardized recipe for vegetarian vegetable saup used at University Hospital, Cleveland, 0 io. Expected Yield: 303 liters Total Weight: 367.47 kg Vegetarian Vegetable Soup % Weight Instructions 63.20 l.Add water to kettl— e, using automatic water fill. tomato juice 11.36 2.Set agitator on speed tomatoes, whole 6.29 2 1/2. Add all ingre- tomato puree 3.21 dients except celer— carr, diced 6mm 2.47 y, cabbage, corn, peas, onions, diced 6mm 1.97 and rice. Cook at baby lima beans, 0.99 88°C for 2 hours. frozen potatoes, diced 6mm 0.99 margarine 0.49 wax beans, frozen 0.49 green beans, frozen 0.49 salt 0.45 sugar, granulated 0.15 thyme, ground 0.01 marjoram 0.01 . 3. Add celerya. Cook celery, diced 6mm 2.96 for 30 minutes. 4. Add cabbage, corn, cabbage, coarsely peas and rice and . chopped 1.97 simmer until rice ls corn, frozen 0.99 cooked (about 30 peas, frozen 0.99 mins.). Taste soup, rice, long grain 0.49 add more salt I If needed. total 100.00 5. Bring temperature to 82°C. Set to cool hold. 6. Set agitator speed to 4 1/2 and pump. aIn first batch of soup, one half of celery was added in step 3. The remaining celery was 0 room and added during step 4. In first batch of soup, an ad because the cook tasted the sou salt. btained from the ingredient ditional 0.03% salt was added p and decided it needed more Table The tw same 1 sample Please Retasi Mark 1 Pleas or wt Thank 122 Table A-3. Ballot for the pilot consumer taste panel. Consumer Taste Panel Preference Test The two samples you have been given are prepared from the same recipe. Only the method of storage before reheating the sample is different. Please taste the samples and decide which One you prefer. Retaste the samples until you reach a decision. Mark the appropriate line below. I prefer sample #65. I prefer sample #27. I have no preference. Please list reasons why you prefer one sample over the other,v or why you have no preference. Thank you for your participation in our study. Table A 1 Date/ E Locat F 2/17/84 MSU E Store 2/19/81 Univ Meth Chur 2/20/8 MSU Unic 2/21/ MSU 2/21/ Bur Hi] Ret Ce: 4/5/ MS 4/10 MS 123 lble A-4 Location and comparisons for consumer taste panels to compare quality of chili and soup held chilled and frozen for 30 days in C—300 and PE casinqs. ltE/ . Time Product Planned Main Effect Location Comparison Studied ’17/84 11:30AM Chili Chilled C-300 Packaging MSU Dairya to vs Store 2:30PM Chilled PE Soup Chilled C-300 Storage vs Frozen C—300 11:45AM ’19/84 to Chili Chilled C-300 Storage University 12:15PM vs Method st Frozen C-300 Church Soup Frozen C—300 Packaging vs Frozen PE 12:00PM ’20/84 to Chili Frozen C-300 Packaging MSU 12:15PM vs Unionc’d Frozen PE Soup Chilled PE Storage vs Frozen PE 11:30AM /2l/84 to Chili Chilled C-300 Storage MSU Dairy 2:30PM vs Frozen C-300 Soup Chilled PE Packaging vs Chilled C—300 5:00PM _ /2l/84 to Chili Chilled C—300 Packaging Burcham 6:30PM _ V§ Hillse’ Chilled PE Retirement Soup Chilled C—300 Storage Center VS Frozen C—300 11:30AM . /5/84 to Chili Chilled PE Storage MSU Dairyg 2:30PM vs Frozen ~E Soup Chilled C—300 Storage vs Frozen C—300 11:30AM - A “ _ . /lO/84 to Chili Frozen t—aOO rackaglng msu Dairyg 2:30PM VS“ Frozen :E Soup Chilled PE Storage vs Frozen PE ____'—————‘ Table 124 Table A—4. Location and comparisons for consumer taste panels to compare quality of chili and soup held chilled and frozen for 30 days in C-300 and PE casings. aLocated in Anthony Hall, Farm Lane, MSU, East Lansing, MI. bLocated at 1120 S. Harrison Rd., East Lansing, MI. CLocated on West Circle Drive, MSU, East Lansing, MI. _Results of this panel were not included in the study. The chili was not served to the panelists, because a small leak in the casing allowed water from the reheating process to enter the casing. The temperature of the soup served to the panelists should have been 260°C but was only 43-49°C. eLocated on Burcham Drive, East Lansing, MI. fResults of the panel were not included in the study because the sample was too small to be included in the statistical analysis. 9Chili and soup used for these panels were from the second batch Of product produced on 03/07/84. For all other consumer panels, chili and soup were from the first batch of products produced on 01/17/84. Table l The fo same s reheat Please you pr If yor tastir Mark 1 Pleas or wh Mark Pleas or w} Thanl 125 Table A—5. Ballot for consumer taste panel to compare chllled and frozen chili and soup in C—300 or PE casings. Date: CONSUMER TASTE PANEL PREFERENCE TEST Please fill in the following information: AGE SEX The four samples you have been given are prepared from the same soup or chili recipe. Only the method of storage before reheating is different. Please taste the soup or chili samples and decide which one you prefer. Retaste the samples until you reach a decision. If you taste chili or soup first, please drink water before tasting the other samples (soup or chili). Mark the appropriate line below. CHILI I prefer sample #38. I prefer sample #48. I have no preference. Please list reasons why you prefer one chili over the other, or why you have no preference. Mark the appropriate line below. SOUP I prefer sample #83. I prefer sample #26. _ I have no preference. Please list reasons why you prefer one soup over the other, or why you have no preference. Thank you for your participation in our study. Table QUAN'. PROD PREL 126 Table A-6. Quantitative descriptive analysis (QDA): preliminary analysis of sensory characteristics. QUANTITATIVE DESCRIPTIVE ANALYSIS PRODUCT: DATE: PRELIMINARY ANALYSIS: Taste the product and write down the five or six most prominent sensory characteristics that you can distinguish. Include APPEARANCE, ODOR, TASTE, AND MOUTHFEEL characteristics. Tab QUA 10 ll 127 Table A-7. Trained taste panel: ballot for chili. PRODUCT CODE # QUANTITATIVE DESCRIPTIVE ANALYSIS PRODUCT: Chili Date: PANELIST: Please judge the sample for intensity of each of the indicated quality factors. Place a slash (/) on the line at the appropriate location to indicate your rating of product quality. FACTOR orange reddish-brown 1.. Appearance ‘ . I absent or weak present or strong 2. Aroma . . . l I 1 thin and mushy chunky and thick 3. Texture . A I I y W broken up or not intact whole or intact 4. Integrity of beans I I I . l I l cold hot 5. Temperature 1 i i l bland overpowering 6. Spicy i E pi mild or strong moderate 7. Beany flavor , l I mild or strong moderate 8. Meaty flavor . ; f4—‘ I present absent 9. Greasiness i t”‘* +—-— Objectionable or strong not objectionable 10. Aftertaste i i I { dislike very much like very much 11.0verall i f t-—' Acceptability THANK YOU FOR YOUR ASSISTANCE I1 Table A‘ QUANTIT PRODUCT PANELIS Pi indica l( 128 Table A—8. Trained taste panel: ballot for vegetarian vegetable soup. PRODUCT CODE # QUANTITATIVE DESCRIPTIVE ANALYSIS Vegetarian PRODUCT: Vegetable Soup DATE: PANELIST: Please judge the sample for intensity of each of the indicated quality factors. Place a slash (/) on the line at the appropriate location to indicate your rating of product quality. FACTOR absent strong 1. Aroma ' | I little much 2. Degree of separation of broth (wateriness) watery thick 3. Consistency of broth pale red-orange 4. Color of broth dull bright & contrasting 5. Color of Vegetables broken—up intact 6. Integrity of Vegetables cold or lukewarm hot and steamy 7. Temperature bland strong 8. Flavor of broth l t” __fl_+___ mushy crunchy 9. Texture of vegetables too much too little or none 10. Greasiness objectionable or strong not objectionable ll. Aftertaste ———4——————————————4——_———.we_eefl.ii__ dislike very much like very much 12. Overall I 1"1_w_1111111114.11 Acceptability THANK YOU FOR YOUR ASSISTANCE Table A‘ 129 Table A-9. ABC Laboratories: Microbial analysesa' of the first batch of chilled and frozen chili and soup stored for 30 days in C-300 and PE caSInqs. (Aerobic) Total Fecal 92 Product Plate Coli- Coli- E2 Salmo- fig Perfrén- Count forms forms Colic nellad Aureuse gens (CFU/qm) (MPN) (MPN) (MPN) (+or-) (CFuzgm) (QFUng) CHILI Chilled c-3oo