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Hard-Cooking and Pickling Eggs as Teaching Aids
Hard-Cooking and Pickling Eggs as Teaching Aids A . J . MAURER
Department of Poultry Science, University of Wisconsin, Madison, Wisconsin 53706 (Received for publication September 23, 1974)
POULTRY SCIENCE 54: 1019-1024, 1975
INTRODUCTION OLLEGE students find it difficult to retain every bit of information presented to them during their college career. However, laboratory exercises help considerably in actually experiencing and better understanding techniques or results. Since many people find themselves at a loss when asked about hardcooking or preserving eggs, a laboratory involving the preparation of hard-cooked, pickled eggs was included in a poultry products technology class to enable students to become directly involved in learning more about preserving eggs. A variety of teaching aids using poultry has been reported. They include such areas as incubation projects, skeleton mounting, social behavior, and actual production exercises (Geiger et al., 1974). However, little has been published describing the classroom use of chicken eggs in cooking or preserving exercises. The information is available in research reports and can readily be adapted for teaching purposes. Publications pertaining to hard-cooking and preservation by pickling can be quite useful
C
Research supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison.
in designing a laboratory exercise. The effect of piercing or drilling the egg shell before cooking to prevent splitting has been reported by Irmiter et al. (1970) and Carter (1972,1973). Peelability has been researched in studies by Swanson (1959), Meehan et al. (1961), Fry etal. (1966), Fuller and Angus (1969), Reinke et al. (1973), and Spencer and Tryhnew (1973). They found that aging of eggs and a pH of at least 8.6 or 8.7 are important for good peelability. Hale and Britton (1974) reported increased ease of peeling freshly laid eggs by cooling in ice water followed by a 10 second reheat. Different methods of hard-cooking eggs have also been discussed in the literature. Irmiter et al. (1970) preferred the boiling water start for hard-cooking eggs, while Holleman (1973) indicated that the cold water start and setting the eggs off the heat source for 15 minutes after the water started to boil prevented discoloration at the yolk-white interface. The effect of initial egg temperature was also compared in the study by Holleman (1973). Baker et al. (1967) reported extensive research on causes and prevention of the discoloration around hard-cooked egg yolks. The formation of the ferrous sulfide ring was also investigated by Fuller and Angus (1969),
1019
Downloaded from http://ps.oxfordjournals.org/ at University of New Orleans on June 2, 2015
ABSTRACT A single laboratory experiment was used to teach several egg-use and preservation practices. Students in a poultry products technology class were asked to hard-cook eggs, observing the effect of age of eggs, shell piercing, initial egg temperature, starting water temperature, and severity of hard-cooking on cracked shells, peelability, and color of the yolk exterior. After the eggs were peeled, some were placed loosely into glass jars. Several pickling solutions were prepared by the students based on available recipes. The effect and role of the individual ingredients were discussed during preparation of the solutions. The heated pickling solutions were then poured over the eggs for seasoning. A final requirement of the class was that of formulating their own pickling solution based on what had been learned in the class. The students were evaluated on their interest, participation, and knowledge of the cooking and preservation practices in an exam.
1020
A. J. MAURER
MATERIALS AND METHODS Eggs. The eggs used were brown Grade A mediums supplied by the University of Wisconsin Poultry Research Laboratory. All the eggs had been aged one week in a 5° C. cooler except for a dozen day-old eggs which were used for a "fresh" egg treatment. Hard-cooking Treatments. The factors of age of eggs, shell piercing, initial egg temperature, starting water temperature, and severity of hard-cooking were compared for their effect on shell cracking, ease of peeling, and color of the albumen-yolk interface. The treatments were as follows: Treatment 1. Controls; one dozen, 5° C , seven-day-old eggs were placed in an aluminum pan containing two liters of 14° C. tap water and then heated on a gas range. The burner was immediately turned off when boiling began and the pan was covered with a lid for 15 minutes of cooking. Promptly after cooking, the eggs were cooled in 14° C. running tap water for five minutes. Cracked
shells were observed and recorded. The eggs were then peeled and six eggs from each dozen were pulled apart to expose the surface of the yolk. Observations pertaining to yolk color were noted for later summarization. The other six eggs from each dozen were saved for pickling. Treatment 2. Fresh eggs; same as Treatment 1 except the eggs were one-day-old. Treatment 3. Pierced shells; same as Treatment 1 except the shells were pierced at the large end with an egg picker. Treatment 4. Warm eggs; same as Treatment 1 except the eggs were warmed to room temperature (21° C.) before submersion in water for hard-cooking. Treatment 5. Warm water; same as Treatment 1 except 58° C. water was used as the starting water temperature. Treatment 6. Overcooking; similar to Treatment 1 except the eggs were hardcooked at a rolling boil for 20 minutes and then left to cool slowly in the water in which they were cooked.
Pickling Treatments. Two pickling solutions were prepared for seasoning and preserving the hard-cooked eggs. Sweet and Sour Eggs 1-1/2 cups apple cider 1/2 cup cider vinegar 1 package (about 12 oz.) red cinnamon candy 1 tablespoon mixed pickling spice 2 teaspoons salt 1 teaspoon garlic salt Kansas Spicy Eggs 1-1/2 cups apple cider 1 cup white vinegar 2 teaspoons salt 1 teaspoon mixed pickling spice 1 clove peeled garlic 1/2 sliced onion 1/2 teaspoon mustard seed
Downloaded from http://ps.oxfordjournals.org/ at University of New Orleans on June 2, 2015
Irmiter et al. (1970), and Holleman (1973). There is general agreement that moderate heat during hard-cooking (less than a boil) and rapid cooling lessen the degree of discoloration around the yolk. Additional information on preservation of hard-cooked eggs is also available. Specific egg-pickling bulletins by Cunningham et al. (1971) and Maurer (1974) can be useful in designing a laboratory exercise. The role of acetic acid and its strength on rate of penetration, as well as the effect of sugar and aging on tenderness and flavor, have also been discussed by Acton and Johnson (1973), Ball et al. (1973), and McCready (1973). In an attempt to more effectively teach the science of hard-cooking and preservation of eggs by pickling, a laboratory exercise was designed involving a variety of the procedures previously discussed.
EGGS AS TEACHING AIDS
RESULTS AND DISCUSSION Hard-cooking Treatments. Treatment 1 followed most of the recommendations for
proper hard-cooking of eggs (Holleman, 1973; Anonymous, 1974a, b; Maurer, 1974). The results obtained were quite satisfactory for yolk color, but two eggs cracked during hard-cooking. To dramatize the problem that usually occurs when trying to peel fresh hard-cooked eggs, Treatment 2 was conducted and the results observed by the class can be seen in Fig. 1. Poor separation of the shell from the albumen resulted in difficult peeling and a torn and unattractive peeled egg. The older eggs peeled quite well because the outer and inner shell membranes separated easily. Shell piercing before hard-cooking has been recommended by Carter (1973), but relatively few people follow that practice because of an unawareness of the recommendation or a lack of knowledge as to how the piercing should be done. A thumb tack can be used if a conventional egg picker is not available. The results observed by the class during
7-day- old egqs
/- day O'd ejqS
FIG. 1. A peeled comparison of seven-day-old and one-day-old hard-cooked eggs.
Downloaded from http://ps.oxfordjournals.org/ at University of New Orleans on June 2, 2015
The mixtures were heated to near boiling and simmered for five minutes. The solutions were then poured over the hard-cooked eggs which were packed in quart jars. The effects of the individual ingredients were discussed to indicate the role of each in the pickling solutions. The class then formulated a third pickling solution on their own to provide a different color and flavor to the eggs. At the end of the laboratory session, the jars were capped and placed in the refrigerator for seasoning. One week later the pickled eggs were observed and tasted, noting the flavor and color derived from the pickling solutions. Several weeks later the students were questioned in an examination about their knowledge of hard-cooking and pickling eggs.
1021
1022
A. J. MAURER
There is a belief by some that it is advisable to start with warm eggs to prevent excessive shell splitting during cooking. It is felt that the egg contents would not have to expand as much during the remainder of the heat-up period. However, when warm eggs were used, the class observed that two hard-cooked eggs out of a dozen exhibited small cracks in Treatment 4. On the other hand, starting with warm water and cold eggs is believed to cause excessive pressure buildup inside an egg during hard-cooking because the expanding gases have so little time during heat-up to escape through the shell. Treatment 5 produced small cracks in three eggs, but did not exhibit severe shell splitting as might have been expected. Treatments 1 through 5 provided very acceptable yellow albumen-yolk interface colors. However, it was very obvious to the class that severe hard-cooking conditions in
FIG. 2. Typical ingredients used for egg pickling and the resulting pickled Japanese quail eggs.
Downloaded from http://ps.oxfordjournals.org/ at University of New Orleans on June 2, 2015
Treatment 3 suggested that egg piercing might reduce cracked shells after hard-cooking, but does not eliminate the problem entirely. In fact, the small pierced hole can become plugged with cooked albumen and a pressure buildup inside the egg can still cause shell cracking during heating and expansion of gases. A disadvantage of shell piercing noted during the experiment was that the small hole seemed to provide a weak spot which then allowed small hairline cracks to form. Irmiter et al. (1970) also reported the formation of hairline cracks in drilled eggs. However, pierced eggs did not crack as severely as control eggs where some of the albumen exuded and disfigured one of the hard-cooked eggs. Piercing is reported to be most beneficial in older eggs. Carter (1973) explained that a 28-day-old egg, for instance, needs a pierced hole for release of pressure during cooking because the shell becomes less permeable after seven days of aging.
1023
EGGS AS TEACHING AIDS
Treatment 6 caused blackening of the yolk surface of every egg due to the formation of ferrous sulfide (FeS). As observed in the earlier treatments, moderate heat for hardcooking eggs was preferable because of a more attractive yolk.
The class concluded the laboratory exercise by formulating their own pickled egg recipe. The usual ingredients of vinegar and salt were used. In addition, dill seed and green food coloring were included along with several other spices to provide the flavor balance desired. The pickled eggs were a success, but it is felt that a few adjustments in the class recipe could improve their pickling solution. The class was told that the refrigerated pickled eggs would be bacteriologically and organoleptically acceptable for several months as a result of the proper hard-cooking and pickling procedures used in the experiment. Participation by the students was excellent during the laboratory exercise, and a written examination several weeks later which included the subject matter on hardcooking and pickling indicated that the students retained 86.5% of the information discussed on that day. It was felt that the techniques presented in this paper were an effective way to use hard-cooking and pick-
REFERENCES Acton, J. C , and M. G. Johnson, 1973. Pickled eggs. 1. pH, rate of acid penetration into egg components and bacteriological analysis. Poultry Sci. 52: 107111. Anonymous, 1974a. Consumers ask about hard-cooked eggs. Poultry Tribune, Aug., p. 31. Anonymous, 1974b. Five basic methods of egg cooking. Am. Egg Board, 205 Touhy Ave., Park Ridge, Illinois. Baker, R. C , J. Darflerand A. Lifshitz, 1967. Factors affecting the discoloration of hard-cooked egg yolks. Poultry Sci. 46: 664-672. Ball, H. R., Jr., and M. W. Saffores, 1973. Eggs pickled in various acid strength solutions. Poultry Sci. 52: 916-920. Carter, T. C , 1972. The hen's egg: factors affecting shell splitting during boiling. Brit. Poultry Sci. 13: 341-355. Carter, T. C , 1973. Hen's egg: effect of a hole in shell on incidence of splitting during cooking. Brit. Poultry Sci. 14:485-491. Cunningham, F. E., D. J. Mugler and M. E. Jackson, 1971. Try pickling eggs at home. Cooperative Ext. Ser., Kansas State Univ., Manhattan, Kansas. Bull. L-227. Fry, J. L., G. M. Herrick and E. M. Ahmed, 1966. Effect of irradiation on the peeling of newly laid eggs hard-cooked following irradiation. Food Technol. 20: 1371. Fuller, G. W., and P. Angus, 1969. Peelability of hard-cooked eggs. Poultry Sci. 48: 1145-1151. Geiger, G. S., D. W. MacLaury, G. D. Quigley, F. D. Rollins, E. A. Schano and D. W. Talmadge, 1974. Science studies in poultry biology. Poultry Sci. 53: 455-503. Hale, K. K., Jr., and W. M. Britton, 1974. Peeling hard cooked eggs by rapid cooling and reheating. Poultry Sci. 53: 1069-1077. Holleman, K. A., 1973. Soft and hard cooking of shell eggs. Poultry Sci. 52: 2042. Irmiter, T. F., L. E. Dawson and J. G. Reagan, 1970. Methods of preparing hard cooked eggs. Poultry Sci. 49: 1232-1236. Maurer, A. J., 1974. Preserving and pickling eggs at home. Cooperative Ext. Prog., Univ. of Wisconsin, Madison. Fact Sheet A2455. McCready, S. T., 1973. Temperature, percent sugar and pH effects on the flavor development and tenderness of pickled eggs. Poultry Sci. 52: 13101317. Meehan, J. J., T. F. Sugihara and L. Kline, 1961.
Downloaded from http://ps.oxfordjournals.org/ at University of New Orleans on June 2, 2015
Pickling Treatments. The two pickling treatments as listed in the Materials and Methods section provided satisfactory and tasty preserved hard-cooked eggs. Fig. 2 shows the ingredients and resulting product derived from the red cinnamon candy on pickled Japanese quail eggs. Discussion with the class was used to point out the necessity of the acetic acid in cider and vinegar to penetrate the eggs and lower the pH for effective preservation. Salt was used to enhance flavor and make the pickling solution less desirable for bacterial growth. Other ingredients and spices were used to attain appropriate and desired flavors.
ling eggs as teaching aids.
1024
A. J. MAURER
Relation between internal egg quality stabilization and peeling difficulty. Poultry Sci.-40: 1430-1431. Reinke, W. C , J. V. Spencer and L. J. Tryhnew, 1973. The effect of storage upon the chemical, physical and functional properties of chicken eggs. Poultry Sci. 52: 692-702.
Spencer, J. V., and L. J. Tryhnew, 1973. Effect of storage on peeling quality and flavor of hard-cooked shell eggs. Poultry Sci. 52: 654-657. Swanson, M. H., 1959. Some observations on the peeling problem of fresh and shell-treated eggs when hard cooked. Poultry Sci. 38: 1253-1254.
Heat Pasteurization of Mechanically Deboned Poultry Meat* MACNEIL
University Park, PA 16802
(Received for publication September 30, 1974)
ABSTRACT Mechanically deboned poultry meat (MDPM), which had been stuffed into frankfurter casings, was heat pasteurized in a water bath for up to 6 minutes at temperatures of 59° C , 62° C , 65° C , 68° C , or 71° C. Using data from total aerobic plate counts, a thermal destruction curve was prepared showing the time-temperature relationships required to achieve equal degrees of pasteurization. Pasteurized samples of MDPM were stored at 3° C. for up to 12 days and at -18° C. for up to 25 weeks. The shelf-life of MDPM (as measured by total bacterial numbers) was extended by heat pasteurization since the initial level of bacteria was greatly reduced. However, the rate of bacterial growth in pasteurized MDPM was equivalent to or slightly greater than in non-pasteurized MDPM. POULTRY SCIENCE 54: 1024-1030, 1975
INTRODUCTION
ECHANICALLY deboned poultry meat (MDPM) has become a useful and very valuable by-product of the poultry processing industry. However, like other raw, comminuted meat products, it is susceptible to microbial spoilage unless handled under sanitary conditions and proper temperatures. Therefore, most MDPM produced is either frozen or immediately incorporated into a product which is heat-treated. Ostovar et al. (1971) investigated the microbiological quality of mechanically deboned broiler necks and backs, whole fowl, and turkey racks. The initial average microbial count of these products was 4.6 x 105/g. This increased to more than 1.0 x 108/g.
M
*Authorized for publication on April 25, 1974 as journal series paper number 4683 of the Pennsylvania Agricultural Experiment Station.
when stored at 3° C. for 12 days and decreased to approximately 8.0 x 103/g. when stored at —15° C. for 270 days. The predominant psychrotolerant bacteria which they isolated were species of Pseudomonas, Flavobacterium, and Achromobacter. Maxcy et al. (1973) examined the microbial quality of both hand-deboned and MDPM. They also found the initial microbial level to be approximately 1.0 x 105/g. Within four days of storage at 5° C , this level of bacteria increased to 1.0 x 107 - 1.0 x 108/g. When held at -20° C. for seven weeks, the bacterial population remained relatively constant at approximately 1.0 x 104/g. Bacillus species (35%) and gram negative rods (25%) accounted for most of the microflora isolated. Froning et al. (1971) used fresh MDPM to produce frankfurters (15% MDPM) without adversely affecting the microbiological quality. However, when MDPM which had been frozen for 90 days was used, an inferior product was produced which was detected
Downloaded from http://ps.oxfordjournals.org/ at University of New Orleans on June 2, 2015
M. G. M A S T AND J. H .
Division of Food Science and Industry, The Pennsylvania State University,
Department of Poultry Science, University of Wisconsin, Madison, Wisconsin 53706 (Received for publication September 23, 1974)
POULTRY SCIENCE 54: 1019-1024, 1975
INTRODUCTION OLLEGE students find it difficult to retain every bit of information presented to them during their college career. However, laboratory exercises help considerably in actually experiencing and better understanding techniques or results. Since many people find themselves at a loss when asked about hardcooking or preserving eggs, a laboratory involving the preparation of hard-cooked, pickled eggs was included in a poultry products technology class to enable students to become directly involved in learning more about preserving eggs. A variety of teaching aids using poultry has been reported. They include such areas as incubation projects, skeleton mounting, social behavior, and actual production exercises (Geiger et al., 1974). However, little has been published describing the classroom use of chicken eggs in cooking or preserving exercises. The information is available in research reports and can readily be adapted for teaching purposes. Publications pertaining to hard-cooking and preservation by pickling can be quite useful
C
Research supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison.
in designing a laboratory exercise. The effect of piercing or drilling the egg shell before cooking to prevent splitting has been reported by Irmiter et al. (1970) and Carter (1972,1973). Peelability has been researched in studies by Swanson (1959), Meehan et al. (1961), Fry etal. (1966), Fuller and Angus (1969), Reinke et al. (1973), and Spencer and Tryhnew (1973). They found that aging of eggs and a pH of at least 8.6 or 8.7 are important for good peelability. Hale and Britton (1974) reported increased ease of peeling freshly laid eggs by cooling in ice water followed by a 10 second reheat. Different methods of hard-cooking eggs have also been discussed in the literature. Irmiter et al. (1970) preferred the boiling water start for hard-cooking eggs, while Holleman (1973) indicated that the cold water start and setting the eggs off the heat source for 15 minutes after the water started to boil prevented discoloration at the yolk-white interface. The effect of initial egg temperature was also compared in the study by Holleman (1973). Baker et al. (1967) reported extensive research on causes and prevention of the discoloration around hard-cooked egg yolks. The formation of the ferrous sulfide ring was also investigated by Fuller and Angus (1969),
1019
Downloaded from http://ps.oxfordjournals.org/ at University of New Orleans on June 2, 2015
ABSTRACT A single laboratory experiment was used to teach several egg-use and preservation practices. Students in a poultry products technology class were asked to hard-cook eggs, observing the effect of age of eggs, shell piercing, initial egg temperature, starting water temperature, and severity of hard-cooking on cracked shells, peelability, and color of the yolk exterior. After the eggs were peeled, some were placed loosely into glass jars. Several pickling solutions were prepared by the students based on available recipes. The effect and role of the individual ingredients were discussed during preparation of the solutions. The heated pickling solutions were then poured over the eggs for seasoning. A final requirement of the class was that of formulating their own pickling solution based on what had been learned in the class. The students were evaluated on their interest, participation, and knowledge of the cooking and preservation practices in an exam.
1020
A. J. MAURER
MATERIALS AND METHODS Eggs. The eggs used were brown Grade A mediums supplied by the University of Wisconsin Poultry Research Laboratory. All the eggs had been aged one week in a 5° C. cooler except for a dozen day-old eggs which were used for a "fresh" egg treatment. Hard-cooking Treatments. The factors of age of eggs, shell piercing, initial egg temperature, starting water temperature, and severity of hard-cooking were compared for their effect on shell cracking, ease of peeling, and color of the albumen-yolk interface. The treatments were as follows: Treatment 1. Controls; one dozen, 5° C , seven-day-old eggs were placed in an aluminum pan containing two liters of 14° C. tap water and then heated on a gas range. The burner was immediately turned off when boiling began and the pan was covered with a lid for 15 minutes of cooking. Promptly after cooking, the eggs were cooled in 14° C. running tap water for five minutes. Cracked
shells were observed and recorded. The eggs were then peeled and six eggs from each dozen were pulled apart to expose the surface of the yolk. Observations pertaining to yolk color were noted for later summarization. The other six eggs from each dozen were saved for pickling. Treatment 2. Fresh eggs; same as Treatment 1 except the eggs were one-day-old. Treatment 3. Pierced shells; same as Treatment 1 except the shells were pierced at the large end with an egg picker. Treatment 4. Warm eggs; same as Treatment 1 except the eggs were warmed to room temperature (21° C.) before submersion in water for hard-cooking. Treatment 5. Warm water; same as Treatment 1 except 58° C. water was used as the starting water temperature. Treatment 6. Overcooking; similar to Treatment 1 except the eggs were hardcooked at a rolling boil for 20 minutes and then left to cool slowly in the water in which they were cooked.
Pickling Treatments. Two pickling solutions were prepared for seasoning and preserving the hard-cooked eggs. Sweet and Sour Eggs 1-1/2 cups apple cider 1/2 cup cider vinegar 1 package (about 12 oz.) red cinnamon candy 1 tablespoon mixed pickling spice 2 teaspoons salt 1 teaspoon garlic salt Kansas Spicy Eggs 1-1/2 cups apple cider 1 cup white vinegar 2 teaspoons salt 1 teaspoon mixed pickling spice 1 clove peeled garlic 1/2 sliced onion 1/2 teaspoon mustard seed
Downloaded from http://ps.oxfordjournals.org/ at University of New Orleans on June 2, 2015
Irmiter et al. (1970), and Holleman (1973). There is general agreement that moderate heat during hard-cooking (less than a boil) and rapid cooling lessen the degree of discoloration around the yolk. Additional information on preservation of hard-cooked eggs is also available. Specific egg-pickling bulletins by Cunningham et al. (1971) and Maurer (1974) can be useful in designing a laboratory exercise. The role of acetic acid and its strength on rate of penetration, as well as the effect of sugar and aging on tenderness and flavor, have also been discussed by Acton and Johnson (1973), Ball et al. (1973), and McCready (1973). In an attempt to more effectively teach the science of hard-cooking and preservation of eggs by pickling, a laboratory exercise was designed involving a variety of the procedures previously discussed.
EGGS AS TEACHING AIDS
RESULTS AND DISCUSSION Hard-cooking Treatments. Treatment 1 followed most of the recommendations for
proper hard-cooking of eggs (Holleman, 1973; Anonymous, 1974a, b; Maurer, 1974). The results obtained were quite satisfactory for yolk color, but two eggs cracked during hard-cooking. To dramatize the problem that usually occurs when trying to peel fresh hard-cooked eggs, Treatment 2 was conducted and the results observed by the class can be seen in Fig. 1. Poor separation of the shell from the albumen resulted in difficult peeling and a torn and unattractive peeled egg. The older eggs peeled quite well because the outer and inner shell membranes separated easily. Shell piercing before hard-cooking has been recommended by Carter (1973), but relatively few people follow that practice because of an unawareness of the recommendation or a lack of knowledge as to how the piercing should be done. A thumb tack can be used if a conventional egg picker is not available. The results observed by the class during
7-day- old egqs
/- day O'd ejqS
FIG. 1. A peeled comparison of seven-day-old and one-day-old hard-cooked eggs.
Downloaded from http://ps.oxfordjournals.org/ at University of New Orleans on June 2, 2015
The mixtures were heated to near boiling and simmered for five minutes. The solutions were then poured over the hard-cooked eggs which were packed in quart jars. The effects of the individual ingredients were discussed to indicate the role of each in the pickling solutions. The class then formulated a third pickling solution on their own to provide a different color and flavor to the eggs. At the end of the laboratory session, the jars were capped and placed in the refrigerator for seasoning. One week later the pickled eggs were observed and tasted, noting the flavor and color derived from the pickling solutions. Several weeks later the students were questioned in an examination about their knowledge of hard-cooking and pickling eggs.
1021
1022
A. J. MAURER
There is a belief by some that it is advisable to start with warm eggs to prevent excessive shell splitting during cooking. It is felt that the egg contents would not have to expand as much during the remainder of the heat-up period. However, when warm eggs were used, the class observed that two hard-cooked eggs out of a dozen exhibited small cracks in Treatment 4. On the other hand, starting with warm water and cold eggs is believed to cause excessive pressure buildup inside an egg during hard-cooking because the expanding gases have so little time during heat-up to escape through the shell. Treatment 5 produced small cracks in three eggs, but did not exhibit severe shell splitting as might have been expected. Treatments 1 through 5 provided very acceptable yellow albumen-yolk interface colors. However, it was very obvious to the class that severe hard-cooking conditions in
FIG. 2. Typical ingredients used for egg pickling and the resulting pickled Japanese quail eggs.
Downloaded from http://ps.oxfordjournals.org/ at University of New Orleans on June 2, 2015
Treatment 3 suggested that egg piercing might reduce cracked shells after hard-cooking, but does not eliminate the problem entirely. In fact, the small pierced hole can become plugged with cooked albumen and a pressure buildup inside the egg can still cause shell cracking during heating and expansion of gases. A disadvantage of shell piercing noted during the experiment was that the small hole seemed to provide a weak spot which then allowed small hairline cracks to form. Irmiter et al. (1970) also reported the formation of hairline cracks in drilled eggs. However, pierced eggs did not crack as severely as control eggs where some of the albumen exuded and disfigured one of the hard-cooked eggs. Piercing is reported to be most beneficial in older eggs. Carter (1973) explained that a 28-day-old egg, for instance, needs a pierced hole for release of pressure during cooking because the shell becomes less permeable after seven days of aging.
1023
EGGS AS TEACHING AIDS
Treatment 6 caused blackening of the yolk surface of every egg due to the formation of ferrous sulfide (FeS). As observed in the earlier treatments, moderate heat for hardcooking eggs was preferable because of a more attractive yolk.
The class concluded the laboratory exercise by formulating their own pickled egg recipe. The usual ingredients of vinegar and salt were used. In addition, dill seed and green food coloring were included along with several other spices to provide the flavor balance desired. The pickled eggs were a success, but it is felt that a few adjustments in the class recipe could improve their pickling solution. The class was told that the refrigerated pickled eggs would be bacteriologically and organoleptically acceptable for several months as a result of the proper hard-cooking and pickling procedures used in the experiment. Participation by the students was excellent during the laboratory exercise, and a written examination several weeks later which included the subject matter on hardcooking and pickling indicated that the students retained 86.5% of the information discussed on that day. It was felt that the techniques presented in this paper were an effective way to use hard-cooking and pick-
REFERENCES Acton, J. C , and M. G. Johnson, 1973. Pickled eggs. 1. pH, rate of acid penetration into egg components and bacteriological analysis. Poultry Sci. 52: 107111. Anonymous, 1974a. Consumers ask about hard-cooked eggs. Poultry Tribune, Aug., p. 31. Anonymous, 1974b. Five basic methods of egg cooking. Am. Egg Board, 205 Touhy Ave., Park Ridge, Illinois. Baker, R. C , J. Darflerand A. Lifshitz, 1967. Factors affecting the discoloration of hard-cooked egg yolks. Poultry Sci. 46: 664-672. Ball, H. R., Jr., and M. W. Saffores, 1973. Eggs pickled in various acid strength solutions. Poultry Sci. 52: 916-920. Carter, T. C , 1972. The hen's egg: factors affecting shell splitting during boiling. Brit. Poultry Sci. 13: 341-355. Carter, T. C , 1973. Hen's egg: effect of a hole in shell on incidence of splitting during cooking. Brit. Poultry Sci. 14:485-491. Cunningham, F. E., D. J. Mugler and M. E. Jackson, 1971. Try pickling eggs at home. Cooperative Ext. Ser., Kansas State Univ., Manhattan, Kansas. Bull. L-227. Fry, J. L., G. M. Herrick and E. M. Ahmed, 1966. Effect of irradiation on the peeling of newly laid eggs hard-cooked following irradiation. Food Technol. 20: 1371. Fuller, G. W., and P. Angus, 1969. Peelability of hard-cooked eggs. Poultry Sci. 48: 1145-1151. Geiger, G. S., D. W. MacLaury, G. D. Quigley, F. D. Rollins, E. A. Schano and D. W. Talmadge, 1974. Science studies in poultry biology. Poultry Sci. 53: 455-503. Hale, K. K., Jr., and W. M. Britton, 1974. Peeling hard cooked eggs by rapid cooling and reheating. Poultry Sci. 53: 1069-1077. Holleman, K. A., 1973. Soft and hard cooking of shell eggs. Poultry Sci. 52: 2042. Irmiter, T. F., L. E. Dawson and J. G. Reagan, 1970. Methods of preparing hard cooked eggs. Poultry Sci. 49: 1232-1236. Maurer, A. J., 1974. Preserving and pickling eggs at home. Cooperative Ext. Prog., Univ. of Wisconsin, Madison. Fact Sheet A2455. McCready, S. T., 1973. Temperature, percent sugar and pH effects on the flavor development and tenderness of pickled eggs. Poultry Sci. 52: 13101317. Meehan, J. J., T. F. Sugihara and L. Kline, 1961.
Downloaded from http://ps.oxfordjournals.org/ at University of New Orleans on June 2, 2015
Pickling Treatments. The two pickling treatments as listed in the Materials and Methods section provided satisfactory and tasty preserved hard-cooked eggs. Fig. 2 shows the ingredients and resulting product derived from the red cinnamon candy on pickled Japanese quail eggs. Discussion with the class was used to point out the necessity of the acetic acid in cider and vinegar to penetrate the eggs and lower the pH for effective preservation. Salt was used to enhance flavor and make the pickling solution less desirable for bacterial growth. Other ingredients and spices were used to attain appropriate and desired flavors.
ling eggs as teaching aids.
1024
A. J. MAURER
Relation between internal egg quality stabilization and peeling difficulty. Poultry Sci.-40: 1430-1431. Reinke, W. C , J. V. Spencer and L. J. Tryhnew, 1973. The effect of storage upon the chemical, physical and functional properties of chicken eggs. Poultry Sci. 52: 692-702.
Spencer, J. V., and L. J. Tryhnew, 1973. Effect of storage on peeling quality and flavor of hard-cooked shell eggs. Poultry Sci. 52: 654-657. Swanson, M. H., 1959. Some observations on the peeling problem of fresh and shell-treated eggs when hard cooked. Poultry Sci. 38: 1253-1254.
Heat Pasteurization of Mechanically Deboned Poultry Meat* MACNEIL
University Park, PA 16802
(Received for publication September 30, 1974)
ABSTRACT Mechanically deboned poultry meat (MDPM), which had been stuffed into frankfurter casings, was heat pasteurized in a water bath for up to 6 minutes at temperatures of 59° C , 62° C , 65° C , 68° C , or 71° C. Using data from total aerobic plate counts, a thermal destruction curve was prepared showing the time-temperature relationships required to achieve equal degrees of pasteurization. Pasteurized samples of MDPM were stored at 3° C. for up to 12 days and at -18° C. for up to 25 weeks. The shelf-life of MDPM (as measured by total bacterial numbers) was extended by heat pasteurization since the initial level of bacteria was greatly reduced. However, the rate of bacterial growth in pasteurized MDPM was equivalent to or slightly greater than in non-pasteurized MDPM. POULTRY SCIENCE 54: 1024-1030, 1975
INTRODUCTION
ECHANICALLY deboned poultry meat (MDPM) has become a useful and very valuable by-product of the poultry processing industry. However, like other raw, comminuted meat products, it is susceptible to microbial spoilage unless handled under sanitary conditions and proper temperatures. Therefore, most MDPM produced is either frozen or immediately incorporated into a product which is heat-treated. Ostovar et al. (1971) investigated the microbiological quality of mechanically deboned broiler necks and backs, whole fowl, and turkey racks. The initial average microbial count of these products was 4.6 x 105/g. This increased to more than 1.0 x 108/g.
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*Authorized for publication on April 25, 1974 as journal series paper number 4683 of the Pennsylvania Agricultural Experiment Station.
when stored at 3° C. for 12 days and decreased to approximately 8.0 x 103/g. when stored at —15° C. for 270 days. The predominant psychrotolerant bacteria which they isolated were species of Pseudomonas, Flavobacterium, and Achromobacter. Maxcy et al. (1973) examined the microbial quality of both hand-deboned and MDPM. They also found the initial microbial level to be approximately 1.0 x 105/g. Within four days of storage at 5° C , this level of bacteria increased to 1.0 x 107 - 1.0 x 108/g. When held at -20° C. for seven weeks, the bacterial population remained relatively constant at approximately 1.0 x 104/g. Bacillus species (35%) and gram negative rods (25%) accounted for most of the microflora isolated. Froning et al. (1971) used fresh MDPM to produce frankfurters (15% MDPM) without adversely affecting the microbiological quality. However, when MDPM which had been frozen for 90 days was used, an inferior product was produced which was detected
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M. G. M A S T AND J. H .
Division of Food Science and Industry, The Pennsylvania State University,