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Thermally Processed Hard Cooked Eggs1
Thermally Processed Hard Cooked Eggs1 W. J. STADELMAN, A. I. IKEME, R. A. ROOP 5 , and S. E. SIMMONS3
Food Science Institute, Purdue University, West Lafayette, Indiana 47907 (Received for publication April 27, 1981)
1982 Poultry Science 61:388-391 INTRODUCTION Attempts have been made to preserve hard cooked eggs by canning. A US patent was issued to Trelease et al. (1952), but eggs in cans did not become a common grocery store item. Organic acids or other chelating compounds such as phosphates were necessary to minimize or eliminate discoloration on the yolk surface of many hard cooked eggs. The value of chelating compounds in preventing ferrous sulfide discoloration in eggs was confirmed by Gossett and Baker (1981). Ball and Saffones (1972) found that because of slow acid penetration into the yolk, pH equilibrium of hard cooked eggs and an acidic solution took from 4 to 10 days. Acton and Johnson (1973) reported a pH equilibrium between the solution and yolk in 3 to 6 days. In 1977, some mechandisers attempted to retail hard cooked eggs in clear plastic bags. Consumers were interested but poor handling in the retail outlets and by consumers resulted in bulged packages. The expanded bags were observed to be the result of gas production by bacteria as well as expansion of air in the
'journal paper No. 8517 Purdue Agricultural Experiment Station, West Lafayette, IN 47907. 2 Present address: Central Soya Co., Inc., 1300 Ft. Wayne National Building, Research Center, Ft. Wayne, IN 46802. 'Present address: L. S. Heath & Sons, Inc., 206 S. Jackson, Robinson, IL 62454.
nonevacuated packages when they were placed in warm environments (unpublished data). The objective of this study was to determine the technical feasibility of packaging hard cooked eggs in retortable pouches for distribution through retail stores. MATERIALS AND METHODS The first experiment of the study was to determine changes in texture, flavor, and appearance of canned hard cooked eggs when subjected to a retort temperature of 121 C for 15 min. This was accomplished by hard cooking eggs following the recommended method by Maurer (1975). The eggs were cooled and shells were removed. Intact eggs with no breaks in the albumen were placed in 303 X 406 cans with a dilute (2%) malic acid (pH 4.0) and .5% sodium chloride solution and sealed. Cans were heated in a rotary retort for 15 min at 15 psi (121 C). A thermocouple was placed near the center of an egg in some cans to determine maximum temperature attained. The cans were cooled and stored at temperatures of 22 C and 38 C for 30 days and 4 C for more than 1 year. Within 2 hr of canning and sterilization some cans were opened to measure processing effects on the eggs. A second experiment in the study was to package two eggs in each of 120 retortable pouches with a .1 N citric acid and .2% sodium benzoate solution, pH 3.75. The eggs used in diis study were cooked and peeled in a commercial plant by the method of Maurer (1975)
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ABSTRACT Peeled hard cooked eggs were held in .1 N citric acid containing .2% sodium benzoate at 4 C for 4 days. The eggs were then packed in sealed metal cans and in retortable pouches in a dilute organic acid. They were retorted for 15 min at 121 C. Other eggs in retortable pouches were immersed in boiling water for 15 min. The previously hard cooked eggs endured the stresses of retorting or immersion in boiling water with no detectable changes in sensory characteristics. Microbiological examination of thermally processed eggs after 1 week, 4 weeks, 3 months, and 5 months storage at 4 C or 21 C gave no evidence of growth of microorganisms. Hard cooked eggs can be packaged and thermally processed without harm to sensory qualities. Such eggs could be merchandised with or without refrigeration. (Key words- hard cooked eggs, egg preservation, thermal processing, citric acid)
RESEARCH NOTE 4 days prior t o packaging in p o u c h e s . During this time, the eggs were stored at 4 C in a .1 N citric acid, .2% sodium b e n z o a t e solution, p H 3.75. This solution was recycled for r e t o r t p o u c h packaging of some eggs as indicated in Table 1. T h e p o u c h e s were 14 cm by 17.5 cm m a d e from a mylar, a l u m i n u m foil, polyp r o p y l e n e laminate. T h e packages of eggs and 2% citric acid solution were sealed using a Swissvac (Minor) 4 sealer u n d e r a 6 8 0 m m Hg vacuum. T h e evacuated packages were subjected to boiling water ( 9 9 C for 15 min), r e t o r t e d ( 1 2 1 C for 15 m i n ) , or were given n o h e a t t r e a t m e n t . Packages were held at 4 C and 22 C for times of 1 week, 4 weeks, 3 m o n t h s or
4 Swissvac Minor vacuum packaging machine (Model 500) Transvac-Maschinen Ag, 6010 Kriens, Lupen, Switzerland.
c o o k e d eggs had been held at 4 C for 4 days, referred to as used solution. The p H of t h e used solution was 5.83 in replicate 1 and 5.74 in replicate 2. RESULTS AND DISCUSSION Experiment 1. In t h e r e t o r t t r e a t m e n t of canned eggs initial pH of the malic acid solution was 4 . 0 . Immediately after processing, t h e p H was 4.5 and after 24 hr it had increased t o 6.0, indicating a relatively rapid equilibration of p H b e t w e e n the acid and eggs. Storage time and t e m p e r a t u r e influenced the color of the c o o k e d eggs. Trelease et al. ( 1 9 5 2 ) reported t h a t after several m o n t h s storage a t 21 or 38 C, t h e t e x t u r e of t h e w h i t e canned eggs was the same as t h a t of a freshly boiled egg, the color of t h e w h i t e was n o t d a r k e n e d t o an objectionable e x t e n t , t h e color of the yolk was a natural yellow, and the flavor of the egg c o m p a r e d favorably with t h a t of a freshly boiled egg. Results of this study confirmed the w o r k of Trelease et al. ( 1 9 5 2 ) with respect to t e x t u r e in this research b u t t h e color of the albumen was a light tan when the eggs were stored for 30 days at 38 C or for 8 m o n t h s at 22 C, n o t w h i t e as r e p o r t e d b y Trelease et al. ( 1 9 5 2 ) . Flavor was comparable t o a h a r d c o o k e d egg h e l d for several days in a refrigerator b u t n o t to t h e flavor of a freshly cooked egg. Yolk color was n o r m a l and all traces of any darkened area o n the surface of t h e y o l k were dissipated. The first packages were p r e p a r e d with organic acid only. When
TABLE 1. Design of Experiment 2 using retortable pouches for packaging hard cooked eggs1 Heat treatment 2 None Fresh solution 3 Used solution"
20 5 20
99 C water 15 min 20 20
121 C steam 15 min 20 20
1 Hard cooked eggs prepared by method of Maurer (1975) and stored in citric acid — .2% sodium benzoate solution (pH 3.75) for 4 days prior to packaging. 2 Hard cooked eggs packed in 14 X 17.5 cm pouches made from a mylar, aluminum foil, polypropylene laminate and sealed with 680 mm Hg vacuum drawn. 3
Citric acid and .2% sodium benzoate at pH 3.75.
4
Citric acid and .2% sodium benzoate solution taken from hard cooked eggs after 4 day holding, pH 5.83 and 5.74 in replicates 1 and 2, respectively. 5 Twenty packages in each treatment group. Five packages were removed from each storage temperature (4 and 22 C) after 1 week, 4 weeks, 3 months, and 5 months.
Downloaded from http://ps.oxfordjournals.org/ at Rice University on May 20, 2015
5 m o n t h s . T o t a l plate c o u n t s were by standard m e t h o d s according t o Speck ( 1 9 7 6 ) ; pH meas u r e m e n t of solutions were obtained. Sensory evaluations of t e x t u r e , flavor, and appearance were c o n d u c t e d informally b y 4 t o 6 l a b o r a t o r y workers when packages were o p e n e d for microbiological and p H evaluations following t h e storage times. T w o replications of t h e second e x p e r i m e n t (Table 1) were c o n d u c t e d comparing n o h e a t t r e a t m e n t , boiling water, and steam r e t o r t using a fresh citric acid-sodium b e n z o a t e solution ( p H 3.75) or a similar solution in which hard
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STADELMAN ET AL. after 3 or 5 months of storage. Bacterial counts were obtained from 3 of the 240 packages sampled in the entire study. These were found as 1.5 X 10 3 cfu/ml of solution after 3 months storage of 1 package at 22 C in used solution subjected to the boiling water treatment. The other 2 packages were those with used solution and no heat treatment. Counts were 1 X 10 3 and 6.4 X 10 4 cfu/ml after 3 months storage at 4 and 22 C, respectively. After 5 months at 22 C storage, the color of albumen was normal and flavor was no different from freshly packaged eggs. All eggs accumulated an odor which dissipated soon after the package was opened. After dissipation, the eggs had no detectable off odors or flavors. The pH of solutions in which eggs were stored are reported in Table 2. The pH increased during the 5 months of storage as egg proteins and the solution equilibrated. In the fresh acidic solution used at the time of packaging the pH remained less than 5.0 in all packages. The continual rise in pH during the storage period resulted in values above 4.6. This would require the packaged eggs to be classified
TABLE 2. Average pH values observed in storage solutions after storage of hard cooked eggs, 2 replications, 2 packages each Storage time Used solution
1
Temperature (C)
1 week
4 week
5 months
No processing2 No processing Boiling water 3 Boiling water Retort 4 Retort
4 22 4 22 4 22
5.65 5.85 5.75 5.80 5.75 5.70
5.90 5.95 6.25 6.05 6.05 5.90
6.35 5.95 6.35 6.45 6.35 6.50
New solution 5 No processing2 No processing Boiling water 3 Boiling water Retort" Retort
4 22 4 22 4 22
4.40 4.45 4.30 4.40 4.40 4.50
4.65 4.75 4.70 4.75 4.70 4.75
4.70 4.75 4.80 4.80 4.80 4.80
1 Solution used for packaging eggs in retort pouches had been used to store eggs for 4 days prior to this use, pH averaged 5.79. 2 Package evacuated and sealed, no heat processing. 'Evacuated, sealed packages immersed in water at about 99 C for 15 min. "Evacuated, sealed packages processed in retort at 121 C for 15 min. 5 Solution of citric acid sodium benzoate mixed to a pH of 3.75.
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sodium chloride was added to the solution, the flavor of the canned eggs was less bland. Canned eggs were held at 4 C for over a year with little change in texture or flavor compared to samples stored for one week. The thermocouple inserted into the center of an egg packed in the retorted can indicated that a temperature of 115 C was attained during retorting. This was sufficient to destroy most spoilage organisms. Experiment 2. The microbiological evaluation after 1 week of storage indicated no bacterial growth in any package irrespective of solutions or storage temperature. There was a slight yeast growth in packages with used solution and no thermal processing. Two weeks after packaging of retort pouches,two packages that had used solution and no heat treatment were bulged slightly due to gas formation. As no bacteria were detected using standard plate count procedures, the gas was likely a product of yeast cells detected in low numbers in some packages opened after 1 week of storage. After 4 weeks some mold was found in the packages receiving no heat treatment. There was no evidence of yeast or mold in packages sampled
RESEARCH NOTE ACKNOWLEDGMENTS
This work was supported in part by a grant from the American Egg Board, Park Ridge, IL and by N-K Associates, Inc., Burket, IN. REFERENCES Acton, J. C, and M. G. Johnson, 1973. 1. pH, rate of acid penetration into egg components and bacteriological analyses. Poultry Sci. 52:107— 111. Ball, H. R., and M. W. Saffones, 1972. Eggs pickled in various acid strength solutions. Poultry Sci. 51:1782.(Abstr.) Gossett, P. W., and R. C. Baker, 1981. Prevention of the green-gray discoloration in cooked liquid whole eggs. J. Food. Sci. 46:328-331. Maurer, A. J. 1975. Hard-cooking and pickling eggs as teaching aids. Poultry Sci. 54:1019-1024. Speck, M. L., ed., 1976. Compendium of methods for the microbiological examination of food. Amer. Publ. Health Ass., Washington, DC. Trelease, R. D., G. O. Sampson, and D.V.A. Strand, 1952. Canning of hard boiled eggs. US Pat. No. 2,593,223.
Downloaded from http://ps.oxfordjournals.org/ at Rice University on May 20, 2015
as "low acid" products. Processing requirements would be regulated by 21 CFR Part 113. The effectiveness of the acidic solution in inhibiting bacterial growth was evident from the low percentage of packages having gas production or viable colony forming units when plated. The acid solution plus care to minimize contamination during pouch packaging resulted in non-heat processed pouches keeping for over 5 months with no evidence of spoilage. Yeast and mold growth were controlled by the .2% sodium benzoate at 4 C storage. At 22 C storage the yeast and mold grew for the first few weeks until apparently available oxygen was depleted. Trapped air in the vacuumized packages was measured and found to vary from 3 to 15 ml per package. Results of this research indicate that hard cooked eggs might be packaged and distributed through retail channels with minimal loss due to microbiological spoilage.
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Food Science Institute, Purdue University, West Lafayette, Indiana 47907 (Received for publication April 27, 1981)
1982 Poultry Science 61:388-391 INTRODUCTION Attempts have been made to preserve hard cooked eggs by canning. A US patent was issued to Trelease et al. (1952), but eggs in cans did not become a common grocery store item. Organic acids or other chelating compounds such as phosphates were necessary to minimize or eliminate discoloration on the yolk surface of many hard cooked eggs. The value of chelating compounds in preventing ferrous sulfide discoloration in eggs was confirmed by Gossett and Baker (1981). Ball and Saffones (1972) found that because of slow acid penetration into the yolk, pH equilibrium of hard cooked eggs and an acidic solution took from 4 to 10 days. Acton and Johnson (1973) reported a pH equilibrium between the solution and yolk in 3 to 6 days. In 1977, some mechandisers attempted to retail hard cooked eggs in clear plastic bags. Consumers were interested but poor handling in the retail outlets and by consumers resulted in bulged packages. The expanded bags were observed to be the result of gas production by bacteria as well as expansion of air in the
'journal paper No. 8517 Purdue Agricultural Experiment Station, West Lafayette, IN 47907. 2 Present address: Central Soya Co., Inc., 1300 Ft. Wayne National Building, Research Center, Ft. Wayne, IN 46802. 'Present address: L. S. Heath & Sons, Inc., 206 S. Jackson, Robinson, IL 62454.
nonevacuated packages when they were placed in warm environments (unpublished data). The objective of this study was to determine the technical feasibility of packaging hard cooked eggs in retortable pouches for distribution through retail stores. MATERIALS AND METHODS The first experiment of the study was to determine changes in texture, flavor, and appearance of canned hard cooked eggs when subjected to a retort temperature of 121 C for 15 min. This was accomplished by hard cooking eggs following the recommended method by Maurer (1975). The eggs were cooled and shells were removed. Intact eggs with no breaks in the albumen were placed in 303 X 406 cans with a dilute (2%) malic acid (pH 4.0) and .5% sodium chloride solution and sealed. Cans were heated in a rotary retort for 15 min at 15 psi (121 C). A thermocouple was placed near the center of an egg in some cans to determine maximum temperature attained. The cans were cooled and stored at temperatures of 22 C and 38 C for 30 days and 4 C for more than 1 year. Within 2 hr of canning and sterilization some cans were opened to measure processing effects on the eggs. A second experiment in the study was to package two eggs in each of 120 retortable pouches with a .1 N citric acid and .2% sodium benzoate solution, pH 3.75. The eggs used in diis study were cooked and peeled in a commercial plant by the method of Maurer (1975)
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Downloaded from http://ps.oxfordjournals.org/ at Rice University on May 20, 2015
ABSTRACT Peeled hard cooked eggs were held in .1 N citric acid containing .2% sodium benzoate at 4 C for 4 days. The eggs were then packed in sealed metal cans and in retortable pouches in a dilute organic acid. They were retorted for 15 min at 121 C. Other eggs in retortable pouches were immersed in boiling water for 15 min. The previously hard cooked eggs endured the stresses of retorting or immersion in boiling water with no detectable changes in sensory characteristics. Microbiological examination of thermally processed eggs after 1 week, 4 weeks, 3 months, and 5 months storage at 4 C or 21 C gave no evidence of growth of microorganisms. Hard cooked eggs can be packaged and thermally processed without harm to sensory qualities. Such eggs could be merchandised with or without refrigeration. (Key words- hard cooked eggs, egg preservation, thermal processing, citric acid)
RESEARCH NOTE 4 days prior t o packaging in p o u c h e s . During this time, the eggs were stored at 4 C in a .1 N citric acid, .2% sodium b e n z o a t e solution, p H 3.75. This solution was recycled for r e t o r t p o u c h packaging of some eggs as indicated in Table 1. T h e p o u c h e s were 14 cm by 17.5 cm m a d e from a mylar, a l u m i n u m foil, polyp r o p y l e n e laminate. T h e packages of eggs and 2% citric acid solution were sealed using a Swissvac (Minor) 4 sealer u n d e r a 6 8 0 m m Hg vacuum. T h e evacuated packages were subjected to boiling water ( 9 9 C for 15 min), r e t o r t e d ( 1 2 1 C for 15 m i n ) , or were given n o h e a t t r e a t m e n t . Packages were held at 4 C and 22 C for times of 1 week, 4 weeks, 3 m o n t h s or
4 Swissvac Minor vacuum packaging machine (Model 500) Transvac-Maschinen Ag, 6010 Kriens, Lupen, Switzerland.
c o o k e d eggs had been held at 4 C for 4 days, referred to as used solution. The p H of t h e used solution was 5.83 in replicate 1 and 5.74 in replicate 2. RESULTS AND DISCUSSION Experiment 1. In t h e r e t o r t t r e a t m e n t of canned eggs initial pH of the malic acid solution was 4 . 0 . Immediately after processing, t h e p H was 4.5 and after 24 hr it had increased t o 6.0, indicating a relatively rapid equilibration of p H b e t w e e n the acid and eggs. Storage time and t e m p e r a t u r e influenced the color of the c o o k e d eggs. Trelease et al. ( 1 9 5 2 ) reported t h a t after several m o n t h s storage a t 21 or 38 C, t h e t e x t u r e of t h e w h i t e canned eggs was the same as t h a t of a freshly boiled egg, the color of t h e w h i t e was n o t d a r k e n e d t o an objectionable e x t e n t , t h e color of the yolk was a natural yellow, and the flavor of the egg c o m p a r e d favorably with t h a t of a freshly boiled egg. Results of this study confirmed the w o r k of Trelease et al. ( 1 9 5 2 ) with respect to t e x t u r e in this research b u t t h e color of the albumen was a light tan when the eggs were stored for 30 days at 38 C or for 8 m o n t h s at 22 C, n o t w h i t e as r e p o r t e d b y Trelease et al. ( 1 9 5 2 ) . Flavor was comparable t o a h a r d c o o k e d egg h e l d for several days in a refrigerator b u t n o t to t h e flavor of a freshly cooked egg. Yolk color was n o r m a l and all traces of any darkened area o n the surface of t h e y o l k were dissipated. The first packages were p r e p a r e d with organic acid only. When
TABLE 1. Design of Experiment 2 using retortable pouches for packaging hard cooked eggs1 Heat treatment 2 None Fresh solution 3 Used solution"
20 5 20
99 C water 15 min 20 20
121 C steam 15 min 20 20
1 Hard cooked eggs prepared by method of Maurer (1975) and stored in citric acid — .2% sodium benzoate solution (pH 3.75) for 4 days prior to packaging. 2 Hard cooked eggs packed in 14 X 17.5 cm pouches made from a mylar, aluminum foil, polypropylene laminate and sealed with 680 mm Hg vacuum drawn. 3
Citric acid and .2% sodium benzoate at pH 3.75.
4
Citric acid and .2% sodium benzoate solution taken from hard cooked eggs after 4 day holding, pH 5.83 and 5.74 in replicates 1 and 2, respectively. 5 Twenty packages in each treatment group. Five packages were removed from each storage temperature (4 and 22 C) after 1 week, 4 weeks, 3 months, and 5 months.
Downloaded from http://ps.oxfordjournals.org/ at Rice University on May 20, 2015
5 m o n t h s . T o t a l plate c o u n t s were by standard m e t h o d s according t o Speck ( 1 9 7 6 ) ; pH meas u r e m e n t of solutions were obtained. Sensory evaluations of t e x t u r e , flavor, and appearance were c o n d u c t e d informally b y 4 t o 6 l a b o r a t o r y workers when packages were o p e n e d for microbiological and p H evaluations following t h e storage times. T w o replications of t h e second e x p e r i m e n t (Table 1) were c o n d u c t e d comparing n o h e a t t r e a t m e n t , boiling water, and steam r e t o r t using a fresh citric acid-sodium b e n z o a t e solution ( p H 3.75) or a similar solution in which hard
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STADELMAN ET AL. after 3 or 5 months of storage. Bacterial counts were obtained from 3 of the 240 packages sampled in the entire study. These were found as 1.5 X 10 3 cfu/ml of solution after 3 months storage of 1 package at 22 C in used solution subjected to the boiling water treatment. The other 2 packages were those with used solution and no heat treatment. Counts were 1 X 10 3 and 6.4 X 10 4 cfu/ml after 3 months storage at 4 and 22 C, respectively. After 5 months at 22 C storage, the color of albumen was normal and flavor was no different from freshly packaged eggs. All eggs accumulated an odor which dissipated soon after the package was opened. After dissipation, the eggs had no detectable off odors or flavors. The pH of solutions in which eggs were stored are reported in Table 2. The pH increased during the 5 months of storage as egg proteins and the solution equilibrated. In the fresh acidic solution used at the time of packaging the pH remained less than 5.0 in all packages. The continual rise in pH during the storage period resulted in values above 4.6. This would require the packaged eggs to be classified
TABLE 2. Average pH values observed in storage solutions after storage of hard cooked eggs, 2 replications, 2 packages each Storage time Used solution
1
Temperature (C)
1 week
4 week
5 months
No processing2 No processing Boiling water 3 Boiling water Retort 4 Retort
4 22 4 22 4 22
5.65 5.85 5.75 5.80 5.75 5.70
5.90 5.95 6.25 6.05 6.05 5.90
6.35 5.95 6.35 6.45 6.35 6.50
New solution 5 No processing2 No processing Boiling water 3 Boiling water Retort" Retort
4 22 4 22 4 22
4.40 4.45 4.30 4.40 4.40 4.50
4.65 4.75 4.70 4.75 4.70 4.75
4.70 4.75 4.80 4.80 4.80 4.80
1 Solution used for packaging eggs in retort pouches had been used to store eggs for 4 days prior to this use, pH averaged 5.79. 2 Package evacuated and sealed, no heat processing. 'Evacuated, sealed packages immersed in water at about 99 C for 15 min. "Evacuated, sealed packages processed in retort at 121 C for 15 min. 5 Solution of citric acid sodium benzoate mixed to a pH of 3.75.
Downloaded from http://ps.oxfordjournals.org/ at Rice University on May 20, 2015
sodium chloride was added to the solution, the flavor of the canned eggs was less bland. Canned eggs were held at 4 C for over a year with little change in texture or flavor compared to samples stored for one week. The thermocouple inserted into the center of an egg packed in the retorted can indicated that a temperature of 115 C was attained during retorting. This was sufficient to destroy most spoilage organisms. Experiment 2. The microbiological evaluation after 1 week of storage indicated no bacterial growth in any package irrespective of solutions or storage temperature. There was a slight yeast growth in packages with used solution and no thermal processing. Two weeks after packaging of retort pouches,two packages that had used solution and no heat treatment were bulged slightly due to gas formation. As no bacteria were detected using standard plate count procedures, the gas was likely a product of yeast cells detected in low numbers in some packages opened after 1 week of storage. After 4 weeks some mold was found in the packages receiving no heat treatment. There was no evidence of yeast or mold in packages sampled
RESEARCH NOTE ACKNOWLEDGMENTS
This work was supported in part by a grant from the American Egg Board, Park Ridge, IL and by N-K Associates, Inc., Burket, IN. REFERENCES Acton, J. C, and M. G. Johnson, 1973. 1. pH, rate of acid penetration into egg components and bacteriological analyses. Poultry Sci. 52:107— 111. Ball, H. R., and M. W. Saffones, 1972. Eggs pickled in various acid strength solutions. Poultry Sci. 51:1782.(Abstr.) Gossett, P. W., and R. C. Baker, 1981. Prevention of the green-gray discoloration in cooked liquid whole eggs. J. Food. Sci. 46:328-331. Maurer, A. J. 1975. Hard-cooking and pickling eggs as teaching aids. Poultry Sci. 54:1019-1024. Speck, M. L., ed., 1976. Compendium of methods for the microbiological examination of food. Amer. Publ. Health Ass., Washington, DC. Trelease, R. D., G. O. Sampson, and D.V.A. Strand, 1952. Canning of hard boiled eggs. US Pat. No. 2,593,223.
Downloaded from http://ps.oxfordjournals.org/ at Rice University on May 20, 2015
as "low acid" products. Processing requirements would be regulated by 21 CFR Part 113. The effectiveness of the acidic solution in inhibiting bacterial growth was evident from the low percentage of packages having gas production or viable colony forming units when plated. The acid solution plus care to minimize contamination during pouch packaging resulted in non-heat processed pouches keeping for over 5 months with no evidence of spoilage. Yeast and mold growth were controlled by the .2% sodium benzoate at 4 C storage. At 22 C storage the yeast and mold grew for the first few weeks until apparently available oxygen was depleted. Trapped air in the vacuumized packages was measured and found to vary from 3 to 15 ml per package. Results of this research indicate that hard cooked eggs might be packaged and distributed through retail channels with minimal loss due to microbiological spoilage.
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