INTERRELATIONSHIP BETWEEN CHILI. TIME, HOLDING TEMPERATURE AND PACKAGING PROCEDURE ON SHELF-LIFE OF FRYERS Thom Io: Ike Dunn .oI M. 5. MICHIGAN STATE UNIVERSITY. Edward Horace Farmer 1960 LIBRARY Michigan State 5‘2" U' 'ty INTERRELATIONSHIP BETWEEN CHILL TIME, HOLDING TEMPERATURE AND PACKAGING PROCEDURE ON SHELF-LIFE OF FRYERS BY Edward Horace Farmer AN ABSTRACT Submitted to the College of Agriculture of Michigan State university of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Poultry Science Year 1960 Approvedfi / ((1 Eat/mm. ABSTRACT This study was undertaken to evaluate the interrelationships between chill time, packaging treatment and holding temperature on shelf-life of fryers. Six experiments were conducted using a sufficient number of fryers in each experiment to evaluate birds every two days for 30 calendar days. Birds were evaluated for odor score by a panel of four or five persons, and were classified as acceptable or not acceptable. Bacterial counts were determined on fryers in one experiment. In four experiments fluorescent scores were determined by observing the birds under a "black light" in a darkened room. A combination of these three procedures was made to evaluate the effectiveness of the treatments. Five different packaging materials (Cryovac bags, Cryovac sheets, Mylar, Cellophane and Pliofilm) were used in one or more experiments. These materials were used as either tight fitting PaCkages over the fryers, or as overwraps over tray packaged fryers. Birds were held in ice, or under refrigerated temperatures of 34°F, 36°F, and 48°F. Chill times (ice water) varied from two hours to 48 hours. The temperature of melting ice (33°F) or the refrigeration temperature of 34°F inhibited the growth of odor and slime producing baCteria. Fryers held at 34°F remained acceptable about one week longer than fryers held at 36°F and two weeks longer than those held at 48°F. A holding temperature of 48°F caused a rapid 2 Abstract Edward Horace Farmer deterioration of the product and an early rejection by the panel. Fryers stored in a packaging material that excludes air by partial vacuum and that will minimize subsequent contamination of the fryers showed less growth of spoilage bacteria. On the basis of results obtained, the shelf-life of fryers was favorably influenced by Cryovac, Mylar, Cellophane and Pliofilm in this order respectively. Cryovac and Mylar, when properly applied as tight fitting wraps over the birds, or as tight fitting tray pack overwraps, were effective in increasing shelf-life of fryers. On the basis of odor scores, bacterial counts and fluorescing bacteria, Cryovac wrapped fryers had the longest shelf—life. Birds chilled for only two hours remained acceptable for one week longer than birds similarly packaged and chilled for 24 hours. Chilling for 48 hours reduced the acceptable shelf-life to six days when the holding temperature was raised to 48°F. Fryers chilled two hours and vacuum packaged in Cryovac bags had the longest shelf-life for these experiments. INTERRELATIONSHIP BETWEEN CHILL TIME, HOLDING TEMPERATURE AND PACKAGING PROCEDURE ON SHELF—LIFE OF FRYERS BY Edward Horace Farmer A THESIS Submitted to the College of Agriculture of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Poultry Science Year 1960 ii ACKNOWLEDGEMENT The author wishes to express his sincere appreciation to Dr. W. L. Mallmann and Mr. C. A. Davenport of the Department of Microbiology and Public Health for their cooperation in providing the microbiological data presented in this thesis. An expression of thanks is extended to Mr J. H. MacNeil and Mr. E. O. Essary for their advice and assistance in processing birds used in this study. Mr. L. J. Bratzler of the Department of Food Science is given thanks for the facilities that he made available. A special note of appreciation is given to Dr. L. E. Dawson of the Department of Food Science for his encouragement and assistance which made this thesis possible. The author also wishes to thank Dr. H. C. Zindel and Professor J. A. Davidson of the Poultry Science Department for providing the necessary facilities. TABLE OF I. INTRODUCTION . . . . . . II. LITERATURE REVIEW . . . . III. PROCEDURE . . . . . . . . IV. DISCUSSION . . . . . . V. SUMMARY . . . . . . . . . VI. BIBLIOGRAPHY . . . . . . CONTENTS iii Page 36 43 44 iv LIST OF TABLES Table Page 1. An example of the raw odor evaluation score card used . . . . . . . . . . . . . . . . . . . . . . . 6 2. Average odor scores of fryers held at 36°F . . . . lO 3. A comparison of total bacteria counts of fryers held at 36°F . . . . . . . . . . . . . . . . . . . 12 4. Psychrophilic bacteria counts of fryers held at 36°F . . . . . . . . . . . . . . . . . . . . . . . l7 5. Odor scores of tray packed fryers held at 36°F . . l9 6. Fluorescent scores of fryers held at 36°F . . . . . 20 7. Odor scores of tray packed fryers held at 48°F . . 23 8. Fluorescent scores of fryers held at 48°F . . . . . 25 9. Odor scores of fryers held at 34°F . . . . . . . . 27 10. A comparison of raw odor scores of fryers held at 34°F 0 O O O O O O O O O O O O O O O O O O O O O O 32 11. A comparison of average fluorescent scores of fryers held at 34°F . . . . . . . . . . . . . . . . 33 12. Shelf-life of fryers in relation to packaging material, chill time and holding temperature . . . 39 Figure 1. LIST OF FIGURES Odor scores for fryers held at 36°F .4. . . . . . . Total bacteria counts per square inch of skin surface area on fryers held at 36°F . . . . . . . Psychr0philic bacterial counts per square inch of skin surface of fryers held at 36°F . . . . . . Influence of packaging material on odor scores of tray packed chicken fryers held at 34°F . . . . . . Influence of packaging material and method on odor scores of chicken fryers held at 48°F . . . . . . . Odor scores of fryers held at 34°F . . . . . . . . Odor scores of fryers held at 34°F . . . . . . . . A comparison of fluorescent scores of fryers held at 34°F . . . . . . . . . . . . . . . . . . . . . . Odor scores of fryers held at different temperatures Page 11 13 14 21 24 28 31 34 37 __I INTRODUCTION Dressed poultry, in recent years, has been transported through market channels packed in crushed ice and packaged in wire-bound cases. Many tons of ice have been transported throughout the United States to help maintain poultry meat quality. Transporting ice-packaged poultry is costly and the investment in additional ice-making machinery at processing centers and the heavy equipment used to handle crates is high. Although the use of ice helps to maintain an ideal environment for dressed poultry, problems associated with drip from melting ice and the excessive weight of product, container and ice are intensified. A more efficient method for transporting dressed poultry from processing areas to the retail markets would be to transport pre-cooled dry-packed poultry in refrigerated trucks. This method would allow the packaging operation to be performed in efficient processing plants and would eliminate the ice packaging operations. The development of a packaging method and operation which would yield maximum shelf-life and maintain satisfactory product quality and appearance could increase the speed and efficiency of distributing dressed poultry in market channels. LITERATURE REVIEW Studies involving packaging materials and methods for poultry meat products have usually been concerned with a product treatment as well as a packaging treatment. Spencer §£_§l, (1956), reported the effect on shelf-life of a combination of four packaging treatments and four antibiotic treatments. Half birds from each antibiotic treatment (5 to 10 ppm aureomycin for 10 and 20 minutes) were packaged in cellophane, polyethylene, evacuated heat shrinking polyethylene and evacuated heat shrinking polyvinylidene. Birds were held at 32°F until spoilage resulted. The shelf-life of untreated control birds packaged in both evacuated heat shrinkable films was increased approximately two days over those packaged in cellophane or polyethylene. As antibiotic concentration or dipping time was increased, the shelf- life was lengthened for both evacuated heat shrinking films. Dipping for twenty minutes in a 10 ppm solution gave a five-day shelf-life increase for the group packaged in shrinking polyvinylidene. It appeared that the less permeable polyvinylidene film offers an unfavorable atmosphere for the growth of yeasts and molds. Kish (1953), reported no differences in shelf-life of birds overwrapped with LSAT cellophane, 100 polyethylene film, 100 saran 517 or 120 pliofilm HM. All groups of birds in this test were held at 34-380F in a self-service open-top refrigerator and were unsaleable after 72 hours of storage. As measured by the presence of off-odors, slime and changes in carcass color, 48 hours appeared to be the WI 3 maximum shelf-life. No significant differences were found between films with respect to weight loss through 48 hours of storage. An aureomycin or crystalline chlortetracycline dip prior to packaging with Cryovac or LSAD 300 cellophane resulted in no difference in meat flavor scores due to packaging treatment (Carlin, Hall and Walker, 1957). Birds in this study were stored at 34°F for 11 days. The birds vacuum packed in a Cryovac overwrap frequently had lower bacterial counts and higher flavor scores than did those packaged with an overwrap of LSAD cellophane. For these commercially processed birds, regardless of package or antibiotic treatment, there was a gradual deterioration in the quality of poultry meat. It was suggested that factors other than bacterial numbers determine the flavor score of poultry meat. Wells, Spencer and Stadelman (1958), evaluated the shelf- life of packaged fryers after they were chilled in ice water, water containing 30 ppm chlortetracycline and water containing 30 ppm oxytetracycline. Samples of birds from each treatment were placed on cardboard trays and overwrapped with cellophane, vinylidene chloride copolymer and vinylidene chloride c0polymer (evacuated). Ice chilled fryers overwrapped with vinylidene chloride copolymer (air evacuated) had an increased shelf-life of four days. The antiobiotic treated birds wrapped in vinylidene chloride copolymer 'had an increased shelf-life of two days. Partially removing the air from packages of fryers wrapped in impermeable films reportedly inhibited bacterial growth by reducing oxygen tension. Cotterill (1956), evaluated the development of Pseudomonas -_———I 4 fluorescens on fryers by means of an ultra violet lamp. Carcasses overwrapped with polyethylene, Pliofilm or LSAT ce110phane showed fluorescence after three days of holding. Packaging fresh fryers in polyvinylidene chloride bags prevented fluorescence for 14 days. Dipping cut-up poultry in an aureomycin solution and subsequent packaging in polyethylene, Pliofilm, or cellophane (LSAT) showed fluorescence after eight days of storage. Aureomycin fluoresces in the yellow region of the visible spectrum. Essary g£_§l. (1958), reported that as the chill time of fryers was increased the shelf- life was decreased. Fryers chilled in ice for two or four hours had a longer shelf-life than those chilled for 12, 16, 18, or 24 hours. A short chill time without an aureomycin dip gave longer shelf-life than did a 24 hour chill time with the antibiotic. The longest shelf-life was obtained by a short chill time, antibiotic treatment and storage at low temperature. ”I PROCEDURE Six experiments were conducted to evaluate the influence of Chilling treatment, packaging procedure and holding environment on shelf-life of fryers. The fryers used in each experiment were similar in age and weight and were slaughtered and processed in the same manner. All birds were obtained from the Research Farm of the Poultry Science Department, Michigan State University. Processing Procedure Six birds were hung on a killing wheel, bled by the so- called "Kosher" method (outside cut) and allowed to bleed for two minutes. They were then placed in a roto-matic scalder containing water maintained at a temperature of 128°F i 2°F and semi-scalded for one minute. After scalding, they were manually picked on a dual-drum rubber-fingered picker, hung on shackles and pinned, eviscerated and washed. Fryers were then placed in chill tanks containing water and chipped ice. After chilling for periods from two to 48 hours, each fryer was individually packaged and placed in the appropriate refrigerator. Odg; Eygluatign Fryer halves were removed from treatment environment and Placed on cellophane paper on a stainless steel table in a clean room. After one hour at room temperature, the fryers were evaluated 'bY a panel of four persons who evaluated the birds using a six-point 'hedonic score card as illustrated in Table l. TABLE 1. An example of the raw odor evaluation score card used. RAW ODOR: Name: Date: Code: 1. Normal chicken odor 2. Very slight abnormal odor 3. Slight abnormal odor 4. Abnormal odor 5. Strong disagreeable odor 6. Very offensive odor I I I I I 1 I I I I I I I I I I I I I I I .StandardI StandardI StandardI Standard I I I I I IForeign ' Foreign . Foreign ' Foreignl 'Void ' Void ' Void ' Void ' I I I I I IAccept I Accept I Accept I Accept I I I I I I I I I I 'Reject Reject Reject W In experiments 2, 3, 5 and 6, each fryer half was examined carefully in a dark room before an ultraviolet lamp. This procedure was used to check the development of colonies of fluorescent-type bacteria . . mainly Pseudomonas fluorescence. A score of 0 indicated no fluorescence, l--not over three or four visible fluorescent spots not over two or three mm in diameter, 2--several visible fluorescent colonies not over five mm in diameter, 3--a few larger fluorescent areas visible . . many small, and 4--many large fluorescent areas visible (10 mm or over) E ! . J E 1 I' In Experiment 1, the fryers, after odor evaluations, were evaluated for bacterial incidence and growth. Each half-bird was placed aseptically in a sterile one-gallon glass jar and 400 ml of sterile saline was then added. This volume was chosen in order to have adequate washing action; it approximates the average weight of the half birds. The jar was then vigorously shaken by means of a reciprocal shaker for two minutes at 200 oscillations per minute. Serial dilutions of the diluent were made for plating purposes. One ml of the diluent was routinely used as an inoculum in the tube test procedure. Tryptone glucose extract agar (TGE) was employed as a plating medium for determinig total bacterial count from both rinse and swab diluents. The medium was held at 45-48°C before pouring to avoid destroying the thermal sensitive psychrOphiles. Plates were 8 made in triplicate for each serial dilution and incubated at 20°C and 4.50C. When the plates were incubated at 20°C for 72 hours, growth of both gram-positive and negative mesophilic and psychrophilic bacteria occurred. When the plates were incubated for 4.5°c for seven days only psychrophiles developed. This procedure was done in accordance with Standard Methods for the Examination of Dairy Products (10th Ed.). Experiment 1 Thirty (30) White Rock fryers weighing 2 l/2 to 3 1/2 pounds each were processed, halved and chilled in slush ice for two hours. The birds were divided into four groups of 15 halves each. Birds for Treatment A.were placed in crushed ice in stainless steel pans and placed in a 34°F walk-in type cooler in which the air was moved by a blower. Those for Treatment B were tray-packed and overwrapped with Cryovac film} sealed, and dipped in hot water (200°F) to shrink the film. In Treatment C, birds were tray-packed and overwrapped with.MSDZ andrcellophane, and in Treatment D were overwrapped with Cryovac bags and vacuum packed with 15 inches of vacuum. Birds of Treatments B, C and D were placed in an open display type meat cooler at 34°F. The temperature inside the package was observed to be 36°F. On three days per week (Monday, lVinylidene chloride produced by the Cryovac Company. 2MSD cellophane refers to moisture proof, heat sealing cellophane produced by the Dupont Corporation. Wednesday, and Friday) including the 21st day of holding, one package from each treatment was removed and evaluated for odor. Bacterial counts were taken from each fryer-half the same day. Total counts were determined on each half. Odor scores obtained in Experiment 1 are reported in Table 2. A score of higher than three usually indicated rejection by the panel members. Fryers in Treatments A and B were rejected by the odor panel after 19 and 14 days of storage, respectively; those in Treatment C were found unacceptable after 12 days of storage, and those in Treatment D were acceptable throughout the experiment. Figure 1 illustrates the changes in odor scores which occurred more rapidly after seven days of storage. The odor scores of the tray packaged fryers declined more rapidly than did odor scores of the birds packed in ice or in Cryovac bags. Total bacterial counts per half fryer are presented in Table 3. On the fifth day of holding, the total counts were comparable for all lots (Figure 2). After nine days of holding, fryers in Treatment C showed higher counts than did fryers in Treatments A, B or D. Fryers in Treatments A, B, and C had counts of approximately 109 bacteria per square inch of skin surface after 21 days, while those in Treatment D showed counts of 107 after 21 days of holding. ' Psychrophilic bacterial numbers were obtained by incubating plates at 4.50C for seven days. Figure 3 shows that the initial Psychrophilic count (determined on the second day of holding) was considerably lower than the total count as determined by use of ”ww'J 4 ' I?“ ~ - -"' - I . ' ' --.-Ir ' * 10 TABLE 2. Odor scores of fryers held at 36°F. Treatmentsl Days of storage A B C D Average odor score 2 1.25 1.66 1.00 2.00 5 1.75 1.75 1.25 1.25 7 1.00 1.00 1.25 1.75 9 1.75 2.75 2.75 2.00 12 1.00 2.25 3.25 2.25 14 2.00 3.50 4.00 2.75 16 2.00 3.50 4.25 2.75 19 2.50 4.50 4.50 2.50 21 3.75 4.75 3.00 3.00 lTreatments A Ice pack in 34°F cooler B Cryovac film over tray pack (heat shrunk) C MSD cellophane over tray pack D Cryovac bag (vacuum packed) 11 amp UM>O>HU Moon mmuu ocmzmoHHwo Momm mono UM>0%HU Room ooH .momm so oaon mumhum mom mouoom Hooo momuo>¢ .H HMDOHE mmmnoum mo whoa NN om ma ma va NH OH m ________ J— —— —- Odor Scores WI 12 TABLE 3. A comparison of total bacterial counts of fryers held at 36°F. Tgeatmentsl Days of Storage A pB C D Log of Bacterial Counts 2 3.20 2.85 3.12 2.92 5 2.69 3.07 3.62 3.56 7 3.75 2.95 2.01 3.13 9 3.97 5.05 7.18 3.27 12 4.77 5.40 7.87 4.76 14 5.94 7.98 8.97 5.39 16 6.96 8.51 8.38 7.09 19 8.25 9.05 8.71 6.57 21 8.93 9.09 8.90 7.24 llrgatmgnts A Ice pack in 34°F cooler B Cryovac film over tray pack (heat shrunk) C MSD cellophane over tray pack D Cryovac bag (vacuum packed) 13 .homm um Gan: muohuw so mohm oommusm GHXm MO SUCH wnmovm Hum mucsoo Hmfiumpoonfiamuoe .N WMDOHM ommuoum mo mama mm ON ma 0H . va NH OH m _ _ _ .r _ _ _ t. _ KO qu—w N omvmomd .Eooom> mono. 095.55 0 0 can . Room was» Ho>o onAEOHHmo QwE-III14 xomm hows Hm>o Edam om>o>HU.IiIIIO Hoaooo movm CH xomm oUH CH of Bacterial Counts Log No. 4 l .momm um ode: mnohum mo oommsom cflxm mo floss oumsvm Mom musnoo manouomn Usafinmounommm .m HMDOHm . mmmuoum mo when mm on ma @H ea NH 0H m m a N _ —.I-I b L P _ a _ w a _ \IIIdmd ”0:00“ 550fl> 050—. UM>O>HU Q Q QOOOOOD m 005 I H \o X \ uIIIIIII.“ Moon moan Ho>o magmoHHoU am: IIIIIIIIQ M\\ .\. I N os\ . \ . . LU.. \ xomm ammo Ho>o Edam .Um>omuo . IIIIIO n- \o. o \ 4 I m 9" \ o x .. \ Hoaooo moom 5” Mona 00H III. on. \ \ I s \ . O . out. \.\ \ . \ I D _\ nu \. m 0 \ \ \ \ \ I m .. \_ x on... \ \ I. \ “00.000.000.00. 0 \\ \\\.d I. h. \ \‘I \ \\\.. \od 8\\\I I m .\ \\ \\ \ ¢ .4“? II\\ d _ o III. I.@ Log No. of Bacterial Counts I OH 15 plates incubated at 20°C for 72 hours (Figure 2). Birds in Treatment C had higher bacterial counts after nine days storage than birds in other treatments. Fryers in Treatments A, B and C had total counts of 109 bacteria per square inch of skin area after 21 days of holding when the plates were incubated at 20°C. Treatment D had a total count of 107 after 21 days of storage. The fryers in Treatment A, held in crushed ice, and in Treatment D, held in Cryovac (vacuum packed) had longer shelf- 1ife than did fryers in Treatments B and C which were held in the meat cooler. This experiment showed that holding in ice or over- wrapping with Cryovac resulted in longer shelf-life than did tray packaging. 0n the basis of bacterial counts, the birds packaged in Cryovac bags had the longest shelf-life. Treatment C, overwrapped ‘with cellophane, showed a rapid increase in the numbers of bacteria up to the ninth day of storage. It may be concluded that there “was a rinsing effect exerted on half chickens held in ice so that the bacterial counts were lower from the action. The total bacterial count showed that, after five days of holding, the number of bacteria on birds from each treatment were approximately the same. Between five and nine days of storage 'bacteria increased rapidly on fryers in Treatment C but increased gradually from seven to 21 days of holding. Fryers in Treatment D ‘had the lowest bacterial count throughout 21 days of storage and fryers in Treatments A, B and C had similar counts after 21 days Of holding. Overwrapping fryers with cellophane may provide a favorable environment for the growth of bacteria as indicated by 16 results of bacterial counts on birds in Treatment C. Since certain important spoilage bacteria (psychrophiles) are aerobic in nature, an adequate package limits available oxygen and retards growth. Relatively few psychrOphilic bacteria were present on the fryers at the beginning of each storage period, but their number increased rapidly after the fifth day (Table 4). Experiment 2 Sixty (60) White Rock fryers weighing 2 1/2 to 3 1/2 pounds each were slaughtered, picked, eviscerated and chilled in ice water for 24 hours. After chilling, they were drained while hanging on shackles for ten minutes and divided into four groups of 15 birds each. Each bird was cut into serving pieces and placed on separate pieces of butcher paper until packaged in molded cardboard trays. Birds in Treatment A were overwrapped with MSD cellophane and heat sealed; Treatment B with R-l Pliofilm; Treatment C with Cryovac film; and Treatment D with MSD cellophane in which eight holes (1/4 inch in diameter) had been punched in the top area of the film. The packaged fryers were placed in an open display type meat refrigeratorsdmilar to that used in retail stores. Air at 32°F ‘was agitated within this cooler during the test and temperature inside the packages in the cooler was 36°F. After four, seven, eight and 11 days storage, one bird from each treatment was evaluated for odor scores and for fluorescence. Bacterial counts were not determined in this and subsequent experiments, Since it has been demonstrated that the panel scores, in conjunction TABLE 4. 17 Psychrophilic bacterial counts of fryers held at 36°F. Treatments1 Days of Stgggge A B C D Log of bacterial counts 2 1.36 .57 1.57 .57 5 1.45 1.92 3.10 1.73 7 3.04 2.60 1.79 1.85 9 3.54 5.12 7.10 3.08 12 4.71 5.54 ‘7.62 4.50 14 4.73 8.01 8.77 5.27 16 6.80 8.19 8.27 6.79 19 8.18 8.95 8.57 7.01 21 9.06 9.05 8.87 7.21 lggeatments A Ice pack in 34°F cooler Cryovac film over tray pack (heat shrunk) MSD cellophane over tray pack U0!!! Cryovac bag (vacuum packed) H‘— ~‘ 18 with fluorescent scores, are an adequate method of evaluating acceptable shelf-life. The odor scores are reported in Table 5. Odor of fryers in all treatments remained acceptable for seven days of holding; how- ever, fryers in Treatment C maintained a more acceptable odor than did other fryers in this experiment. In Table 6 are reported the visible fluorescent scores for the birds evaluated. After four days of holding (first evaluation date), small fluorescing colonies of bacteria were seen on the bird from Treatment A. Fluorescence developed about equally on birds in Treatments A, Brand D, but those in Treatment C showed only slight fluorescence at any time during the holding period. Fryers in Treatment C, which were overwrapped with Cryovac film, maintained about two days longer acceptable shelf-life than did fryers in Treatments A, B and D (Figure 4). The result of the impermeability of Cryovac film to air and gases had a pronounced effect on the storage life of the fryers. The shrinking of this material after packaging results in only a small amount of air in the package. These characteristics of this film probably caused these birds to have a longer shelf-life than birds from the other treatments. Experiment 3 Sixty (60) fryers were processed, chilled for 48 hours, drained and cut-up as described before. The birds were divided into four groups of 15 birds each. Birds in Treatment A.were ‘ll- 'J'.“ “SEEP; I 19 TABLE 5. Odor scores of tray packed fryers held at 36°F. 1 Treatments Days of Storage A B C D Average odor score 4 1.25 1.25 1.00 1.25 7 2.37 1.62 2.00 1.62 9 4.62 4.50 3.37 4.75 11 6.00 5.50 4.50 5.25 l IEEEEEEEEE. A MSD cellophane--sea1ed R-l Pliofilm--sealed B C Cryovac--sealed and heat shrunk D MSD cellophane-—eight holes per package--sea1ed 3* _ 20 TABLE 6. Fluorescent scores of fryers held at 36°F. Tgeatments1 Days of Storage ,. A B C Di Fluorescent score 4 1 0 0 0 7 2 2 l 1 £1 9 3 3 1 3 ;I 11 3 3 o 3 I lireatments A MSD cellophane-~sealed B .R-I Pliofilm--sealed C Cryovac--sealed and shrunk D MSD ce110phane--eight holes per package--sealed Odor Scores 21 1 ' +\\ ......__.\. -_.--—-~—---* ooooooOohmooboodax‘ .0 2 I ' l 3 D \ 4 «I \\‘\ \ \ \I— 5 h —0— Cellophane O \ a... 0.00 PliOfilm 0‘ * -'+"' Cryovac film __u_.-— Cellophane (perforated) 6 II Days of Storage FIGURE 4. Influence of packaging material on odor scores of tray packed chicken fryers held at 34°F. IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIF""IIIIIIIIIIIIIIIIIIlllllllllllllllllllllll I 22 packaged in Cryovac bags, vacuum packed with 15 inches of vacuum, and then the bags were heat-shrunk. Birds in Treatment B were placed in trays and the tray packed birds were placed in Cryovac bags and vacuum packed with 15 inches of vacuum and then sealed. Birds in Treatment C were placed on trays and then overwrapped with MSD cellophane and heat sealed. Fryers in Treatment D were placed in plastic trays measuring 8" x 5" x 2", and then overwrapped with MSD cellophane and heat sealed. A11 fryers were placed in an - (meant-59w .'_ open type egg cooler similar to that used in retail stores. The temperature within the cooler ranged from 48 to 50°F. After holding periods of four, five, six, seven and 10 days, one bird from each treatment was evaluated for odor and fluorescence and rated as acceptable or rejected. On the fourth day of storage, (Table 7), the fryers from Treatment C were rejected for odor by at least three panel members. Birds in Treatment B scored only 2.75 after four days; birds in Treatments A and B scored 3.0 or less through six days storage; whereas, the odor score of fryers in Treatments C and D declined more rapidly. Fryers in Treatment A maintained a lower score throughout the study than did birds in any of the other three treatments. The birds in Treatments A and B were rejected after seven days storage; whereas, fryers in Treatments C and D were rejected after four and five days respectively (Figure 5). After 10 days of holding, fryers in Treatments A and B Showed no fluorescence while those in Treatments C and D were given a fluorescent score of 3 (Table 8). 23 TABLE 7. Odor scores of tray packed fryers held at 48°F. Treatmentsl Days of Storage A B C D Average odor score 1 2.50 2.75 2.25 4.25 4 3.75 2.75 4.253 3.25 l 5 3.00 3.00 5.003 6.003 6 3.00 3.00 5.003 6.003 r 7 4.753 5.003 6.003 6.003 10 5.003 6.003 6.003 6.003 1Treatments A Cryovac bag--evacuated, sealed, shrunk B -Cryovac bag over tray pack, evacuated, sealed, shrunk C MSD cellophane over tray pack, sealed D MSD cellophane over plastic tray, sealed 3 Rejected for acceptability by at least three panel members. Odor Scores 24 TI 0 Cryovac bag "' -- """- O Cryovac overwrap ..........o. A Cellophane overwrap H -Hr -—---*---9¢ Cellophane overwrap (plastic tray) A I r i I I I fl 5 Days of Storage FIGURE 5. Influence of packaging material and method on odor scores of chicken fryers held at 48°F. 25 TABLE 8. Fluorescent scores of fryers held at 48°F. Treatmentsl Days of Storage A B C D Fluorescent score 1 1 l 2 3 4 l 1 2 3 5 1 2 3 3 6 0 l 3 3 7 0 1 3 3 10 0 O 3 3 lire—atom A Cryovac bag, vacuum packed, sealed, shrunk B Cryovac over tray packs, vacuum packed, sealed shrunk C ‘Cellophane over tray pack D Cellophane over plastic tray she of in as Fr: ad. twl pa Tr va 51 pa Ea 26 The fryers packaged in Cryovac bags exhibited the longest shelf-life of any birds in this test. Vacuum packing with 15 inches of vacuum appeared to increase the shelf-life. A limited atmosphere in the package appeared to lengthen the storage time of the fryers. Experiment 4 Thirty (30) White Rock fryers were processed and halved as in Experiment 3 and divided into four groups of 15 halves each. Fryers in Treatments B and D were chilled for two hours in slush ice containing 20 ppm Acronize3 which lowers to about 10 ppm with addition of fryers and ice, and Treatments A and C were chilled for two hours in slush ice. Fryers in Treatments A and B were tray packaged and overwrapped with MSD cellophane, and those in Treatments C and D were tray packed and placed in Cryovac bags and vacuum packed with 15 inches of vacuum. All fryers were placed on slatted shelves in a walk-in cooler maintained at 34°F. Starting on the second day after processing, on every Monday, Wednesday and Friday until the 22nd day of holding, one package from each treatment was removed and evaluated for odor. Each bird was rated as either acceptable or not acceptable. Odor scores are reported in Table 9 and Figure 6. After two days of holding, fryers in all treatments had odor scores of 1. After 22 days of storage, fryers in Treatments A, B, C, and D were scored 4.5, 2.5, 3.5, and 2.75 respectively. At the 16th 3A trade name for the antibiotic chlortetracycline, produced by American Cyanamid Company. TABLE 9. "Odor Scores of fryers held at 34°F.' 27 Treatments1 nggiof Storage A B C D Average odor scores 2 1.00 1.00 1.00 1.00 5 1.75 1.00 1.00 1.00 7 1.25 1.00 1.00 1.25 9 2.75 2.25 1.25 2.00 12 1.50 1.00 2.50 2.00 14 2.00 2.75 2.00 0.50 16 2.00 2.00 2.00 2.00 19 4.00 1.75 2.50 3.00 21 4.75 2.25 2.50 2.50 22 4.50 2.50 3.50 2.75 1Treatments A Cellophane tray B Cellophane tray, Acronize C Cryovac bag, vacuum packed D Cryovac bag, vacuum packed, Acronize 28 .moem an new: madame mo mmnoom Hose .6 mmoon ommuoum mo mm Hm ma 0H dd NH PI._ _ _ L . 4 /, / /, a no... DOC/I O/lnq OOGgOJ. .0], NJ urn-3,0010, I: 0! JUI.IIII no I % whom omxumm Esoom> .mNHCOHod town om>omnu go. :o D omxnomm Eosom>tmmn UM>0>HU IIIIQ wNHcouod exomm mono mcmflmOHHoU IIIIO xomm moan mswnmoHHoO .Illll.o II, I. I, p. I, o IIIMflnu... Odor Scores wl 29 day of holding, birds in all treatments were given the same odor score by the panel. Average odor scores for birds in Treatment A decreased rapidly after the 16th day. Fryers.fl1Treatments B and D, treated with Acronize, had the longest shelf-life in this experiment. Birds in both treatments were acceptable by the panel after 22 days of storage. Birds in the control Treatments A and C were rejected after 19 and 21 days, respectively. A short chill time and low temperature seemed to increase the shelf—life of the fryers. Experiments 5 and 6 Results of these experiments will be discussed together because of certain combinations used. In Experiment 5, 30: White Rock fryers weighing between 2 1/2 and 3 1/2 pounds each were processed, and chilled in slush ice for two hours. The 30 birds were divided into four lots of 15 halves each and tray packaged. Each broiler was halved before packaging. Fryers in Treatment A were overwrapped with Cryovac film; in Treatment B overwrapped with "Mylar";4 in Treatment C were overwrapped with Cryovac bags and vacuum packed with 15 inches of vacuum; and birds in Treatment D were placed in Mylar tubes and vacuum packed. All birds were placed on slatted shelves in a 34°F walk-in type cooler equipped with a blower. . Starting on the second day after processing and on every 4A polyester film produced by the DuPont Corporation. 30 second day thereafter including the 30th day, one package from each treatment was removed to another room and scored for odor by four panel members as previously described. Fluorescent scores were assigned each carcass as described before. In Experiment 6, the procedure was the same as that described for Experiment 5, except that only 14 halves were used for each group instead of 15 halves and the tray packed fryers in Treatment D of this experiment were placed in Mylar tubes instead of Mylar bags. However, fryers in the Mylar tubes were vacuum packed as was done in Treatment D of Experiment 5. Because of the identical handling of Experiments 5 and 6, the results have been combined. Odor scores of birds in these experiments are reported in Figure 7 and Table 10. After 30 days of storage there was only a slight decrease in odor scores of birds in all treatments. After 30 days storage, the average scores were 2.15, 1.25, l.75,and 3.0, respectively. No fluorescent bacterial colonies were visible until after the 14th day of storage (Table 11). The degree of fluorescence increased rapidly on birds in Treatment A between the 14th and 30th day of holding, as shown in Figure 8. Fluorescence on birds in Treatment D increased rapidly after 22 days of holding. Fryers in Treatments B and D were scored two for fluorescence after 30 days of storage, while birds in Treatment C were given a fluorescent score of only one after 30 days of storage. Treatment A received an average score of 2.5 after 30 days holding. 31 .movm um cams madman no monoum Hooo .s mmoon omMHoum mo mmmn om wN 0N vN NN 0N ma 0A” ed NH OH m 0 v N V _ _ _ 1 .. _ _ _ _ _ _ _ _ _ omxomm Essom> 383V 3&5 “was: . ..... u omxomm Essum> ANMHUV man um>omuo IIIII d 333 5r... “was: IIIII o Amonuv Edam unbomno JVII. ,ngL .d IIIIIIHIIIII infidai Ilidmflld111JdJWII. .DIII I, U... Odor Scores IIII"IIIIIIIIIIIIIIIIIIIIIIIIII'-IlIIIIIIIIIIIIIIIIIIIlll!I-lllllllllllllllll I TABLE 10. 32 A comparison of raw odor scores of fryers held at 34°F. Treatmentsl Days of Stogage A B C D Average Odor score 2 1.15 1.25 1.50 1.00 4 1.00 1.25 1.15 1.15 6 1.00 1.25 1.15 1.50 8 1.15 2.00 1.75 1.40 10 1.25 1.60 1.15 1.15 12 1.40 1.50 1.15 1.25 14 1.00 1.60 1.50 1.60 16 1.25 2.15 1.75 1.50 18 1.40 1.60 1.50 1.25 20 1.25 1.00 1.50 1.75 22 1.25 2.00 1.75 1.75 24 2.15 1.75 2.40 2.00 26 3.15 1.85 2.25 1.60 28 2.50 2.50 2.00 2.75 30 2.15 1.25 1.75 3.00 1Treatments A Cryovac film (tray) B Mylar film (tray) C Cryovac bag (tray) vacuum packed D Mylar tubes (tray) vacuum packed 33 TABLE 11. A comparison of average fluorescent scores of fryers held at 34°F. Treatmentsl Days of Storage A B C D Fluorescent score l6 0 0 0 0 18 .50 0 O O 20 1.00 0 O 0 22 1.00 0 0 1.00 24 1.50 1.50 0 1.00 26 2.00 1.50 1.50 1.50 28 2.00 2.00 1.50 2.00 30 2.50 2.00 1.50 2.25 1Treatments A Cryovac film (tray) B Mylar film (tray) C Cryovac bag (tray) vacuum packed D Mylar tubes (tray) vacuum packed. 34 .movm um oHos mumhhm mo monoou ucoomohoon mo :OmHHmmEoo d .m mmDOHm omenoum mo mama mH 9H VH NH OH m o _ — H _ b _ _ coxomm.fissom> 3mm”: own om>o>uo IIIII4 €3an EHHmsmHmz IIIII O Ahmuuv EHHM 0m>omho ooxomm Essom> 3mm“: mono» HMHmz . ...o.n_ 40- «Cu <0. <0. .0. «O. «In Fluorescent Scores 35 The average odor score for birds in each treatment remained similar until after the 18th day of holding. Birds in Treatments A and C maintained the highest score for the 30 day holding period. These results would indicate that the gas and moisture-proof characteristics of Cryovac overwrap influenced shelf-life at 34°F. _— | 36 DISCUSSION Influence of Temperature on the Shelf-Life of ngerS' The temperature at which fresh fryers are held is one of the most important single factors in the determination of shelf- 1ife. Initial numbers of bacteria influenced by dressing procedure and length of chill time also affect keeping qualities. Figure 9 illustrates the changes in odor of fryers as influenced by the holding temperature. Odor scores indicated a rapid deterioration of fryer halves held at 48°F and 36°F after the fryers had been held in the chill tank for 24 hours. Fryers held in crushed ice (temperature approximately 33°F) maintained odor scores slightly better than did those held at 34°F. At the end of 21 days the average scores of fryers from these two treatments were about equal. At the holding temperature of 36°F (following a prolonged chill period) the fryer halves deteriorated rapidly after the fifth day and the fryers held at 48°F deteriorated very rapidly. The optimum holding temperature for fresh fryers is at or near the freezing temperature of 32°F. Any variation above this temperature will cause a rapid increase in odor scores and a decrease- in acceptability. The spoilage bacteria will be inhibited to the extent that they will not cause the development of off odor and Slime quickly at the lower temperature. In Experiment 2, a relatively short shelf—life was exhibited by the packaged fryer halves. Each treatment was held in an open display type meat fefrigerator with circulated air. Contributing 37 .mmuoumummEmu ucmHoMMHo um onS mummum mo mouoom Hooo .m mmeHm ommuoum mo mama om mm mm «m mm om ma 3 3 3 S m o v m _ _ _ _ _ _ _ _ _ _ _ _ e _ _ F / J. , ../ .. // /vM/ n I o I O/// :35 V A use; am so om/ Haasofl // lim/ 0 HDOSNIVM/ / //I / I / :35 I // “so; we moon 0 0 ll /.nv ’ /