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Moisture Levels in Frozen Poultry as Related to Thawing Losses, Cooking Losses, and Palatability
RESERPINE EFFECTS REFERENCES
Physiological acclimatization of fowls to a hot humid environment. J. Agr. Sci. 4 3 : 294-322. Keplinger, M. L., G. E. Lanier and W. B. Deichmann, 1959. Effects of environmental temperature on the acute toxicity of a number of compounds in rats. Toxicol. Appl. Pharmacol. 1: 156-161. Moon, R. C , and C. W. Turner, 1959. Effect of reserpine on thyroid activity in rats. Proc. Soc. Exp. Biol. Med. 100: 679-681. Robinson, K. W., and D. H. K. Lee, 1947. The effect of the nutritional plane upon the reactions of animals to heat. J. Anim. Sci. 6: 182-194. Sturkie, P., W. K. Durfee and M. Sheahan, 1958. Effects of reserpine on the fowl. Am. J. Physiol. 194: 184-186. Van Matre, N. S., R. E. Burger and F. W. Lorenz, 1957. Resistance to heat stress following administration of tranquilizing drugs. Poultry Sci. 36: 1165. Weiss, H. S., 1959. The interrelationship of reproductive state and seasonal acclimatization on the hen's resistance to lethal high temperature. Poultry Sci. 38:430-435. Weiss, H. S., and E. Borbely, 1957. Seasonal changes in the resistance of the hen to thermal stress. Poultry Sci. 36: 1383-1384. Woodson, R. E., Jr., H. W. Youngken, E. Schlittler and J. A. Schneider, 1957. Rauwolfia: Botany, Pharmacognosy, Chemistry and Pharmacology. Little, Brown & Co., Boston.
Moisture Levels in Frozen Poultry as Related to Thawing Losses, Cooking Losses, and Palatability 1. CHICKEN BROILERS1 GLENN W. FRONING, MILO H. SWANSON AND H. N. BENSON Department of Poultry Husbandry, University of Minnesota, St. Paul, Minnesota (Received for publication July 17, 1959)
ODERN processing procedures for poultry almost universally include slush ice chilling to achieve prompt cooling and overall improvement in appearance of the finished product. In the case of poultry which is to be frozen, the chilling opera-
M
1 Published as Paper No. 4196, Scientific Journal Series of the Minnesota Agricultural Experiment Station.
tion is also used to permit maximum tenderization before packaging and freezing. These practices give rise to questions concerning the optimum moisture level for processed poultry. The processor is not only interested in the general quality of his product but also in salable weight, which can be sharply affected by the moisture content. On the other hand, the consumer is mainly concerned about the palatability
Downloaded from http://ps.oxfordjournals.org/ by guest on May 8, 2015
Bein, H. J., 1956. The pharmacology of rauwolfia. Pharm. Rev. 8: 435-483. Bianca, W., 1958. The relation between respiratory rate and heart rate in the calf subjected to severe heat stress. J. Agr. Sci. S i : 321-324. Burger, R. E., 1959. Research on tranquilizers in poultry. Feedstuffs, 31(17): 62-65. Burger, R. E., N. S. Van Matre and F. W. Lorenz, 1957. Mechanisms of increased resistance to heat stress by tranquilizing drugs. Poultry Sci. 36: 1107. Burger, R. E., N. S. Van Matre and F. W. Lorenz, 1959. Growth and mortality of chicks and poults fed tranquilizing drugs. Poultry Sci. 38: 508-512. Carlson, C. W., 1956. An effect of reserpine on growing turkeys. Proc. South Dakota Acad. Sci. 35: 186-188. Earl, A. E., 1956. Reserpine (Serpasil) in veterinary practice. J. Am. Vet. Med. Assoc. 129: 227-233. Gilbreath, S. C , L. F. Garvin and Q. B. Welch, 1959. Effect of orally administered reserpine on egg production and quality. Poultry Sci. 38: 535-538. Hewitt, O. H., and R. E. Reynolds, 1957. Tranquilizers in rearing game birds. Proc. Cornell Nutr. Conf. 53-60. Hutchinson, J. C. D., and A. H. Sykes, 1953.
373
374
G. W. FRONING, M. H. SWANSON AND H. N. BENSON
MATERIAL AND METHODS
Seventy chicken broilers grown under uniform conditions of feeding and management so as to minimize initial differences in carcass composition were used in this study. Treatments applied just prior to and during processing were designed to vary the moisture content of the carcasses over a wide range. Forty-eight hours before slaughtering the birds were randomly divided into two equal groups. From the first
group both water and feed were withdrawn in an attempt to partially dehyrate the tissues of the birds. The second group was supplied a wet mash and water ad libitum up to the time of processing. Following dressing and evisceration, birds from each of the above groups were again randomly divided into 5 subgroups for chilling prior to packaging and freezing. One of the subgroups was air chilled for 96 hours; three were chilled in ice slush for periods of 4, 24, and 48 hours; and the fifth subgroup was packaged warm without chilling. Weight losses or gains during the cooling process were measured. Birds subjected to liquid chilling were thoroughly and uniformly drained before packaging. All birds were packaged in polyvinylidene bags which were evacuated and shrunk as under commercial processing conditions. Thawing was accomplished by holding the packaged birds overnight at room temperature. Weight losses sustained during this period were carefully determined, and thawing losses were calculated in terms of percentage weight loss based on weight after chilling. Moisture content of samples of thigh and breast meat of the raw carcass was also measured. Samples from the pectoralis major muscle and cross-section samples of the thigh muscle were quickly diced, weighed, and dried under vacuum for 4 hours at 70°C. To determine weight losses on cooking and for taste panel evaluations, the birds were individually roasted in table-top electric rotissaries. Roasting time was equivalent to 6 minutes per 100 grams of carcass weight. Total cooking losses were ascertained by weighing the birds before and after cooking. Drippings from each bird were collected and weighed. Volatile losses were obtained by difference. Moisture content of the cooked breast and thigh muscles was measured from samples removed in a uniform manner from the side of the bird
Downloaded from http://ps.oxfordjournals.org/ by guest on May 8, 2015
and yield of the cooked bird, both of which may be dependent upon the water content of the tissues. A number of studies have demonstrated that carcasses may take up a considerable amount of water in slush ice chilling (Orr, 1953; Spencer et al., 1956; Tarver et al., 1956; Fromm and Monroe, 1958; and others). In general, the percent moisture absorbed was proportional to the chilling time. Less attention has been given to the fate of moisture absorbed in liquid cooling or to the role moisture level of the tissues plays in palatability of the cooked product. Bailey et al. (1948), working with fresh dressed broilers, reported that much of the water absorbed during ice slush chilling was lost during a subsequent holding period of 18 hours and in the process of cooking. The palatability data failed to show any increase in juiciness in birds chilled in slush ice compared with those chilled in air. The objectives of the work reported here were several: (a) to determine the variation in thawing losses among chicken broilers processed and frozen so as to contain a wide range of tissue moisture; (b) to relate chilling method and time to moisture content of both the uncooked (thawed) and cooked tissues; (c) to measure the effect of chilling procedure on cooking losses; and (d) to ascertain the role of tissue moisture in palatability of the cooked bird as measured by juiciness and flavor scores.
375
MOISTURE IN FROZEN CHICKEN BROILERS
opposite to that from which the raw samples were obtained. Seven of the experimental birds were used to train a taste panel of four members and establish scoring standards. The remaining 63 birds were evaluated in a series of 21 panels involving three birds per panel. Coded samples of breast and thigh muscle were scored independently for flavor and juiciness using a range of 1 to S with 1 denoting least juicy or least desirable flavor and 5 denoting most juicy or most desirable flavor. Since the two preslaughter treatments of withdrawing feed and water versus feeding a wet mash had virtually no measurable effect on subsequent moisture levels of the processed birds, the data from the two groups were combined in analyzing the results for this report. The relationship of weight gain or loss at the time of chilling to thawing loss is shown in Table 1. As might be expected, the air chilled broilers lost considerable moisture before being packaged (17.7%) and this, in turn, was undoubtedly responsible for the small loss on thawing (0.15%). Those birds which were packaged warm to prevent either gain or loss of moisture during chilling still exhibited a fair amount of thawing loss (1.9%). As reported by other investigators, weight gains of carcasses chilled in slush ice continued to increased as the chilling time was lengthened. However, TABLE 1.—Relationship of chilling method to weight changes and thawing losses of chicken broilers Chilling method
Weight change
Air chill 96 hrs. No chill, warm pack Ice slush 4 hrs. Ice slush 24 hrs. Ice slush 48 hrs.
-17.7 — + 4.0 + 8.1 + 10.4
%
Thawing loss
%
0.15 1.90 3.40 5.80 5.70
Chilling Method
Air No Ice Ice Ice
chill 96 hrs. chill, warm pack slush, 4 hrs. slush, 24 hrs. slush, 48 hrs.
Thigh Moisture
Breast Moisture
Raw Cooked
Raw Cooked
%
%
%
%
69.0 71.9 71.0 72.5 72.8
63.1 64.5 63.4 65.1 64.5
67.2 71.2 70.4 72.2 72.1
61.6 64.6 63.5 63.4 64.3
a plateau appeared to be reached with respect to thawing losses, since there was essentially no difference between losses sustained by birds chilled 24 and 48 hours. With this exception, differences in thawing losses resulting from the various chilling treatments were found to be significantly different. The effect of chilling method on percentage moisture in the raw and cooked tissues is reported in Table 2. On the basis of weight changes in chilling, one could predict that the air chilled birds would be significantly lower in moisture content both before and after cooking. The data support this supposition. Although the group means show a slight upward trend in moisture of the raw samples as chilling time in ice slush was increased, the analysis of variance indicated no real difference. On cooking, differences in moisture content narrowed somewhat, and in the case of the thigh samples, there were no significant differences among any of the five chilling methods. Cooked breast samples from air chilled birds, however, were significantly lower in moisture compared to samples from the other four groups. Cooking losses as related to chilling method are presented in Table 3. The results are similar to those obtained for moisture content in that the losses on roasting were significantly lower for the air chilled birds, whereas cooking losses among the remaining four treatments did not prove to
Downloaded from http://ps.oxfordjournals.org/ by guest on May 8, 2015
RESULTS
TABLE 2.—Effect of chilling method on tissue moisture of raw and cooked chicken broiler
376
G. W. FRONING, M. H. SWANSON AND H. N. BENSON
TABLE 3.—Ejfect of chilling method on cooking losses of chicken broilers Volatile loss
Chilling Method
Air chill 96 hrs. No chill, warm pack Ice slush, 4 hrs. Ice slush, 24 hrs. Ice slush, 48 hrs.
Drippings
%
%
4.7 5.2 6.3 5.4 6.8
14.1 18.4 17.8 18.5 18.1
Total loss
%
18.8 23.6 24.1 23.9 24.9
TABLE 4.—Taste scores of chicken broilers as affected by moisture content Group
Percent moisture
Juiciness score*
Flavor score*
Low moisture Thigh Breast
61.4 61.2
3.2 2.9
3.6 3.3
High moisture Thigh Breast
66.0 65.9
3.3 3.4
3.2 3.0
Range of 1 (lowest) to 5 (highest).
Group
Percent moisture
Juiciness score*
Flavor score*
Low moisture Thigh Breast
62.5 61.4
3.0 2.8
3.5 3.4
High moisture Thigh Breast
65.5 65.5
3.1 3.2
3.4 3.3
* Range of 1 (lowest) to 5 (highest).
small and not significant. Breast juiciness, however, was significantly higher for the high moisture samples. These results suggested that flavor differences may be due to leaching out of flavor components in prolonged ice slush chilling rather than to moisture content per se. To eliminate the flavor leaching factor, a comparison was made involving only the birds of the air chill and no chill groups (see Table 5). An analysis of these data revealed no real difference in flavor of thigh or breast attributable to moisture level. Again, breast juiciness scores were significantly higher in the sample groups having the higher moisture content. DISCUSSION It should be emphasized that the chilling methods employed in this study were not intended to simulate those presently used in commercial practice. The principal objective was to vary the moisture content of the muscle tissues as widely as possible in order to study the fate and role of moisture in the birds at the consumer level. Nevertheless, the results do confirm the fact that substantial quantities of water can be added to or subtracted from the carcass by varying the chilling procedure. Under the conditions of this experiment, the only flavor differences which did occur could be largely attributed to leaching effects in those samples held for excessive pe-
Downloaded from http://ps.oxfordjournals.org/ by guest on May 8, 2015
be significantly different despite the group means indicating some tendency for total losses to increase with chilling time in ice slush. Volatile losses were less variable than loss from drippings. An overall evaluation of the taste panel results revealed that, in general, panel members preferred the flavor of the carcasses lowest in moisture content. There was little variation in the mean flavor scores for birds from the air chilled, no chill, and 4 hour ice slush treatments. However, carcasses chilled for 24 and 48 hours in ice slush yielded significantly lower flavor scores. To further study the relationship among moisture content, flavor, and juiciness, the samples of thigh and breast muscles were grouped on the basis of percentage moisture in the cooked meat into high (above 65.0%) and low (below 63.0%) moisture categories. The results are tabulated in Table 4. The higher flavor scores for the low moisture group is again evident. The difference in juiciness scores for the thigh was
TABLE 5.—Effect of moisture content on taste scores of chicken broilers processed by dry ch""
MOISTURE IN FROZEN CHICKEN BROILERS
There is little justification for employing chilling procedures designed to merely increase moisture absorption with the objective of improving juiciness and general palatability. Such practices, aside from being questionable from the ethical standpoint, may lead to definite consumer dissatisfaction. SUMMARY
Frozen chicken broilers which had been processed and chilled so as to produce wide variation in moisture content were thawed and roasted. Thawing losses, moisture content of raw and cooked samples of thigh and breast muscle, cooking losses, and taste scores for flavor and juiciness were ascertained. Results indicated that a large proportion of moisture absorbed in processing and liquid chilling is lost on thawing. Additional losses occur in cooking. Flavor scores were adversely affected by prolonged chilling, and juiciness was not satisfactorily improved by the addition of moisture in processing. REFERENCES Bailey, R. L., G. F. Stewart and B. L. Lowe, 1948. Slush ice cooling of dressed poultry. Refrig. Engr. SS: 369-371. Hurley, W. C , O. J. Kahlenberg, E. M. Funk, L. G. Maharg and N. L. Webb, 19S8. Factors affecting poultry flavor. 1. Inorganic constituents. Poultry Sci. 37 : 1436-1440. Orr, H. L., 1953. Carcass cooling tests. Amer. Egg Poultry Review, IS (9) : 18-20. Pippen, E. L., and A. A. Klose, 1955. Effects of ice water chilling on flavor of chicken. Poultry Sci. 34: 1139. Spencer, J. V., W. E. Watson, W. J. Stadelman and M. C. Ahrens, 1956. Effect of cooling and freezing procedures on consumer acceptability factors of turkey meat. Food Technology, 10: 11-18. Tarver, F. R., Jr., G. C. McGhee and O. E. Goff, 1956. The rate of cooling and water absorption of poultry held in various mediums. Poultry Sci. 35: 905-910.
Downloaded from http://ps.oxfordjournals.org/ by guest on May 8, 2015
riods in ice slush. Thus, normal chilling times used in present day processing plants should not adversely affect the flavor of the product. These results are in agreement with Pippen and Klose (1955) and Hurley et al. (1958). The desirability of adding moisture to chicken broilers in the chilling process with the aim of increasing juiciness in the cooked bird is questionable. Moisture analyses of the roasted samples, on the average, showed little or no increase in moisture content resulting from prolonged liquid chilling. It is true that significant differences were found in juiciness scores of the breast when the samples were grouped on the basis of moisture content only (Table 4), but comments from taste panel members indicated that the increased juiciness detected was of an undesirable "watery" nature. Fat content of the tissues no doubt has an appreciable influence on juiciness, and merely adding moisture may avert a quality of dryness but will not increase what most people recognize as natural juiciness. As reported by Bailey et al. (1948), fresh dressed broilers lose a considerable portion of the moisture picked up in chilling when subsequently held in storage. This can lead to the problem of poultry failing to meet weights which have been certified at the time of processing. On the other hand, birds of high moisture content which are packaged and frozen retain their moisture all the way through market channels, but the problem of excessive drainage of moisture from the bird on thawing confronts the consumer. Any thawing loss is viewed with disfavor, and processors must strive to keep it to a minimum by controlling the moisture added in chilling. The evidence from this study suggests that the use of a liquid chill should be limited to quickly reducing carcass temperature and to improving carcass appearance.
377
Physiological acclimatization of fowls to a hot humid environment. J. Agr. Sci. 4 3 : 294-322. Keplinger, M. L., G. E. Lanier and W. B. Deichmann, 1959. Effects of environmental temperature on the acute toxicity of a number of compounds in rats. Toxicol. Appl. Pharmacol. 1: 156-161. Moon, R. C , and C. W. Turner, 1959. Effect of reserpine on thyroid activity in rats. Proc. Soc. Exp. Biol. Med. 100: 679-681. Robinson, K. W., and D. H. K. Lee, 1947. The effect of the nutritional plane upon the reactions of animals to heat. J. Anim. Sci. 6: 182-194. Sturkie, P., W. K. Durfee and M. Sheahan, 1958. Effects of reserpine on the fowl. Am. J. Physiol. 194: 184-186. Van Matre, N. S., R. E. Burger and F. W. Lorenz, 1957. Resistance to heat stress following administration of tranquilizing drugs. Poultry Sci. 36: 1165. Weiss, H. S., 1959. The interrelationship of reproductive state and seasonal acclimatization on the hen's resistance to lethal high temperature. Poultry Sci. 38:430-435. Weiss, H. S., and E. Borbely, 1957. Seasonal changes in the resistance of the hen to thermal stress. Poultry Sci. 36: 1383-1384. Woodson, R. E., Jr., H. W. Youngken, E. Schlittler and J. A. Schneider, 1957. Rauwolfia: Botany, Pharmacognosy, Chemistry and Pharmacology. Little, Brown & Co., Boston.
Moisture Levels in Frozen Poultry as Related to Thawing Losses, Cooking Losses, and Palatability 1. CHICKEN BROILERS1 GLENN W. FRONING, MILO H. SWANSON AND H. N. BENSON Department of Poultry Husbandry, University of Minnesota, St. Paul, Minnesota (Received for publication July 17, 1959)
ODERN processing procedures for poultry almost universally include slush ice chilling to achieve prompt cooling and overall improvement in appearance of the finished product. In the case of poultry which is to be frozen, the chilling opera-
M
1 Published as Paper No. 4196, Scientific Journal Series of the Minnesota Agricultural Experiment Station.
tion is also used to permit maximum tenderization before packaging and freezing. These practices give rise to questions concerning the optimum moisture level for processed poultry. The processor is not only interested in the general quality of his product but also in salable weight, which can be sharply affected by the moisture content. On the other hand, the consumer is mainly concerned about the palatability
Downloaded from http://ps.oxfordjournals.org/ by guest on May 8, 2015
Bein, H. J., 1956. The pharmacology of rauwolfia. Pharm. Rev. 8: 435-483. Bianca, W., 1958. The relation between respiratory rate and heart rate in the calf subjected to severe heat stress. J. Agr. Sci. S i : 321-324. Burger, R. E., 1959. Research on tranquilizers in poultry. Feedstuffs, 31(17): 62-65. Burger, R. E., N. S. Van Matre and F. W. Lorenz, 1957. Mechanisms of increased resistance to heat stress by tranquilizing drugs. Poultry Sci. 36: 1107. Burger, R. E., N. S. Van Matre and F. W. Lorenz, 1959. Growth and mortality of chicks and poults fed tranquilizing drugs. Poultry Sci. 38: 508-512. Carlson, C. W., 1956. An effect of reserpine on growing turkeys. Proc. South Dakota Acad. Sci. 35: 186-188. Earl, A. E., 1956. Reserpine (Serpasil) in veterinary practice. J. Am. Vet. Med. Assoc. 129: 227-233. Gilbreath, S. C , L. F. Garvin and Q. B. Welch, 1959. Effect of orally administered reserpine on egg production and quality. Poultry Sci. 38: 535-538. Hewitt, O. H., and R. E. Reynolds, 1957. Tranquilizers in rearing game birds. Proc. Cornell Nutr. Conf. 53-60. Hutchinson, J. C. D., and A. H. Sykes, 1953.
373
374
G. W. FRONING, M. H. SWANSON AND H. N. BENSON
MATERIAL AND METHODS
Seventy chicken broilers grown under uniform conditions of feeding and management so as to minimize initial differences in carcass composition were used in this study. Treatments applied just prior to and during processing were designed to vary the moisture content of the carcasses over a wide range. Forty-eight hours before slaughtering the birds were randomly divided into two equal groups. From the first
group both water and feed were withdrawn in an attempt to partially dehyrate the tissues of the birds. The second group was supplied a wet mash and water ad libitum up to the time of processing. Following dressing and evisceration, birds from each of the above groups were again randomly divided into 5 subgroups for chilling prior to packaging and freezing. One of the subgroups was air chilled for 96 hours; three were chilled in ice slush for periods of 4, 24, and 48 hours; and the fifth subgroup was packaged warm without chilling. Weight losses or gains during the cooling process were measured. Birds subjected to liquid chilling were thoroughly and uniformly drained before packaging. All birds were packaged in polyvinylidene bags which were evacuated and shrunk as under commercial processing conditions. Thawing was accomplished by holding the packaged birds overnight at room temperature. Weight losses sustained during this period were carefully determined, and thawing losses were calculated in terms of percentage weight loss based on weight after chilling. Moisture content of samples of thigh and breast meat of the raw carcass was also measured. Samples from the pectoralis major muscle and cross-section samples of the thigh muscle were quickly diced, weighed, and dried under vacuum for 4 hours at 70°C. To determine weight losses on cooking and for taste panel evaluations, the birds were individually roasted in table-top electric rotissaries. Roasting time was equivalent to 6 minutes per 100 grams of carcass weight. Total cooking losses were ascertained by weighing the birds before and after cooking. Drippings from each bird were collected and weighed. Volatile losses were obtained by difference. Moisture content of the cooked breast and thigh muscles was measured from samples removed in a uniform manner from the side of the bird
Downloaded from http://ps.oxfordjournals.org/ by guest on May 8, 2015
and yield of the cooked bird, both of which may be dependent upon the water content of the tissues. A number of studies have demonstrated that carcasses may take up a considerable amount of water in slush ice chilling (Orr, 1953; Spencer et al., 1956; Tarver et al., 1956; Fromm and Monroe, 1958; and others). In general, the percent moisture absorbed was proportional to the chilling time. Less attention has been given to the fate of moisture absorbed in liquid cooling or to the role moisture level of the tissues plays in palatability of the cooked product. Bailey et al. (1948), working with fresh dressed broilers, reported that much of the water absorbed during ice slush chilling was lost during a subsequent holding period of 18 hours and in the process of cooking. The palatability data failed to show any increase in juiciness in birds chilled in slush ice compared with those chilled in air. The objectives of the work reported here were several: (a) to determine the variation in thawing losses among chicken broilers processed and frozen so as to contain a wide range of tissue moisture; (b) to relate chilling method and time to moisture content of both the uncooked (thawed) and cooked tissues; (c) to measure the effect of chilling procedure on cooking losses; and (d) to ascertain the role of tissue moisture in palatability of the cooked bird as measured by juiciness and flavor scores.
375
MOISTURE IN FROZEN CHICKEN BROILERS
opposite to that from which the raw samples were obtained. Seven of the experimental birds were used to train a taste panel of four members and establish scoring standards. The remaining 63 birds were evaluated in a series of 21 panels involving three birds per panel. Coded samples of breast and thigh muscle were scored independently for flavor and juiciness using a range of 1 to S with 1 denoting least juicy or least desirable flavor and 5 denoting most juicy or most desirable flavor. Since the two preslaughter treatments of withdrawing feed and water versus feeding a wet mash had virtually no measurable effect on subsequent moisture levels of the processed birds, the data from the two groups were combined in analyzing the results for this report. The relationship of weight gain or loss at the time of chilling to thawing loss is shown in Table 1. As might be expected, the air chilled broilers lost considerable moisture before being packaged (17.7%) and this, in turn, was undoubtedly responsible for the small loss on thawing (0.15%). Those birds which were packaged warm to prevent either gain or loss of moisture during chilling still exhibited a fair amount of thawing loss (1.9%). As reported by other investigators, weight gains of carcasses chilled in slush ice continued to increased as the chilling time was lengthened. However, TABLE 1.—Relationship of chilling method to weight changes and thawing losses of chicken broilers Chilling method
Weight change
Air chill 96 hrs. No chill, warm pack Ice slush 4 hrs. Ice slush 24 hrs. Ice slush 48 hrs.
-17.7 — + 4.0 + 8.1 + 10.4
%
Thawing loss
%
0.15 1.90 3.40 5.80 5.70
Chilling Method
Air No Ice Ice Ice
chill 96 hrs. chill, warm pack slush, 4 hrs. slush, 24 hrs. slush, 48 hrs.
Thigh Moisture
Breast Moisture
Raw Cooked
Raw Cooked
%
%
%
%
69.0 71.9 71.0 72.5 72.8
63.1 64.5 63.4 65.1 64.5
67.2 71.2 70.4 72.2 72.1
61.6 64.6 63.5 63.4 64.3
a plateau appeared to be reached with respect to thawing losses, since there was essentially no difference between losses sustained by birds chilled 24 and 48 hours. With this exception, differences in thawing losses resulting from the various chilling treatments were found to be significantly different. The effect of chilling method on percentage moisture in the raw and cooked tissues is reported in Table 2. On the basis of weight changes in chilling, one could predict that the air chilled birds would be significantly lower in moisture content both before and after cooking. The data support this supposition. Although the group means show a slight upward trend in moisture of the raw samples as chilling time in ice slush was increased, the analysis of variance indicated no real difference. On cooking, differences in moisture content narrowed somewhat, and in the case of the thigh samples, there were no significant differences among any of the five chilling methods. Cooked breast samples from air chilled birds, however, were significantly lower in moisture compared to samples from the other four groups. Cooking losses as related to chilling method are presented in Table 3. The results are similar to those obtained for moisture content in that the losses on roasting were significantly lower for the air chilled birds, whereas cooking losses among the remaining four treatments did not prove to
Downloaded from http://ps.oxfordjournals.org/ by guest on May 8, 2015
RESULTS
TABLE 2.—Effect of chilling method on tissue moisture of raw and cooked chicken broiler
376
G. W. FRONING, M. H. SWANSON AND H. N. BENSON
TABLE 3.—Ejfect of chilling method on cooking losses of chicken broilers Volatile loss
Chilling Method
Air chill 96 hrs. No chill, warm pack Ice slush, 4 hrs. Ice slush, 24 hrs. Ice slush, 48 hrs.
Drippings
%
%
4.7 5.2 6.3 5.4 6.8
14.1 18.4 17.8 18.5 18.1
Total loss
%
18.8 23.6 24.1 23.9 24.9
TABLE 4.—Taste scores of chicken broilers as affected by moisture content Group
Percent moisture
Juiciness score*
Flavor score*
Low moisture Thigh Breast
61.4 61.2
3.2 2.9
3.6 3.3
High moisture Thigh Breast
66.0 65.9
3.3 3.4
3.2 3.0
Range of 1 (lowest) to 5 (highest).
Group
Percent moisture
Juiciness score*
Flavor score*
Low moisture Thigh Breast
62.5 61.4
3.0 2.8
3.5 3.4
High moisture Thigh Breast
65.5 65.5
3.1 3.2
3.4 3.3
* Range of 1 (lowest) to 5 (highest).
small and not significant. Breast juiciness, however, was significantly higher for the high moisture samples. These results suggested that flavor differences may be due to leaching out of flavor components in prolonged ice slush chilling rather than to moisture content per se. To eliminate the flavor leaching factor, a comparison was made involving only the birds of the air chill and no chill groups (see Table 5). An analysis of these data revealed no real difference in flavor of thigh or breast attributable to moisture level. Again, breast juiciness scores were significantly higher in the sample groups having the higher moisture content. DISCUSSION It should be emphasized that the chilling methods employed in this study were not intended to simulate those presently used in commercial practice. The principal objective was to vary the moisture content of the muscle tissues as widely as possible in order to study the fate and role of moisture in the birds at the consumer level. Nevertheless, the results do confirm the fact that substantial quantities of water can be added to or subtracted from the carcass by varying the chilling procedure. Under the conditions of this experiment, the only flavor differences which did occur could be largely attributed to leaching effects in those samples held for excessive pe-
Downloaded from http://ps.oxfordjournals.org/ by guest on May 8, 2015
be significantly different despite the group means indicating some tendency for total losses to increase with chilling time in ice slush. Volatile losses were less variable than loss from drippings. An overall evaluation of the taste panel results revealed that, in general, panel members preferred the flavor of the carcasses lowest in moisture content. There was little variation in the mean flavor scores for birds from the air chilled, no chill, and 4 hour ice slush treatments. However, carcasses chilled for 24 and 48 hours in ice slush yielded significantly lower flavor scores. To further study the relationship among moisture content, flavor, and juiciness, the samples of thigh and breast muscles were grouped on the basis of percentage moisture in the cooked meat into high (above 65.0%) and low (below 63.0%) moisture categories. The results are tabulated in Table 4. The higher flavor scores for the low moisture group is again evident. The difference in juiciness scores for the thigh was
TABLE 5.—Effect of moisture content on taste scores of chicken broilers processed by dry ch""
MOISTURE IN FROZEN CHICKEN BROILERS
There is little justification for employing chilling procedures designed to merely increase moisture absorption with the objective of improving juiciness and general palatability. Such practices, aside from being questionable from the ethical standpoint, may lead to definite consumer dissatisfaction. SUMMARY
Frozen chicken broilers which had been processed and chilled so as to produce wide variation in moisture content were thawed and roasted. Thawing losses, moisture content of raw and cooked samples of thigh and breast muscle, cooking losses, and taste scores for flavor and juiciness were ascertained. Results indicated that a large proportion of moisture absorbed in processing and liquid chilling is lost on thawing. Additional losses occur in cooking. Flavor scores were adversely affected by prolonged chilling, and juiciness was not satisfactorily improved by the addition of moisture in processing. REFERENCES Bailey, R. L., G. F. Stewart and B. L. Lowe, 1948. Slush ice cooling of dressed poultry. Refrig. Engr. SS: 369-371. Hurley, W. C , O. J. Kahlenberg, E. M. Funk, L. G. Maharg and N. L. Webb, 19S8. Factors affecting poultry flavor. 1. Inorganic constituents. Poultry Sci. 37 : 1436-1440. Orr, H. L., 1953. Carcass cooling tests. Amer. Egg Poultry Review, IS (9) : 18-20. Pippen, E. L., and A. A. Klose, 1955. Effects of ice water chilling on flavor of chicken. Poultry Sci. 34: 1139. Spencer, J. V., W. E. Watson, W. J. Stadelman and M. C. Ahrens, 1956. Effect of cooling and freezing procedures on consumer acceptability factors of turkey meat. Food Technology, 10: 11-18. Tarver, F. R., Jr., G. C. McGhee and O. E. Goff, 1956. The rate of cooling and water absorption of poultry held in various mediums. Poultry Sci. 35: 905-910.
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riods in ice slush. Thus, normal chilling times used in present day processing plants should not adversely affect the flavor of the product. These results are in agreement with Pippen and Klose (1955) and Hurley et al. (1958). The desirability of adding moisture to chicken broilers in the chilling process with the aim of increasing juiciness in the cooked bird is questionable. Moisture analyses of the roasted samples, on the average, showed little or no increase in moisture content resulting from prolonged liquid chilling. It is true that significant differences were found in juiciness scores of the breast when the samples were grouped on the basis of moisture content only (Table 4), but comments from taste panel members indicated that the increased juiciness detected was of an undesirable "watery" nature. Fat content of the tissues no doubt has an appreciable influence on juiciness, and merely adding moisture may avert a quality of dryness but will not increase what most people recognize as natural juiciness. As reported by Bailey et al. (1948), fresh dressed broilers lose a considerable portion of the moisture picked up in chilling when subsequently held in storage. This can lead to the problem of poultry failing to meet weights which have been certified at the time of processing. On the other hand, birds of high moisture content which are packaged and frozen retain their moisture all the way through market channels, but the problem of excessive drainage of moisture from the bird on thawing confronts the consumer. Any thawing loss is viewed with disfavor, and processors must strive to keep it to a minimum by controlling the moisture added in chilling. The evidence from this study suggests that the use of a liquid chill should be limited to quickly reducing carcass temperature and to improving carcass appearance.
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