The Effect of Ethanol on Shelf-Life and Flavor of Chicken Meat1

The Effect of Ethanol on Shelf-Life and Flavor of Chicken Meat1

PREDICTION OF EGG WEIGHT Poultry Sci. 33: 155-169. Lerner, I. M., and D. Cruden, 1948. The heritability of accumulative monthly and of annual egg pro...

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PREDICTION OF EGG WEIGHT

Poultry Sci. 33: 155-169. Lerner, I. M., and D. Cruden, 1948. The heritability of accumulative monthly and of annual egg production. Poultry Sci. 27: 67-78. Lerner, I. M., 1951. The heritability of egg weight: The advantage of mass selection and of early measurements. Poultry Sci. 30: 34-41. Lerner, I. M., and L. W. Taylor, 1940. A note on the use of short-time trapnesting in breeding selection. Poultry Sci. 19: 187-190. Maw, A. J. G., and W. A. Maw, 1932. A method of estimating the mean annual egg weight. Sci. Agr. 12: 281-286.

The Effect of Ethanol on Shelf-Life and Flavor of Chicken Meat1 KENNETH N. HALL AND JOHN V. SPENCER Department of Animal Sciences, Washington State University, Pullman (Received for publication October 8, 1963)

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OOD sanitation, rapid chilling and low-temperature holding appear to be the most practical means of maintaining the shelf-life of poultry meat. Chicken fryers which had been preserved by freezing were found, upon thawing, to have the same shelf-life and flavor as unfrozen controls (Spencer et al., 1961). Chlortetracycline and oxytetracycline are used to inhibit spoilage bacteria, but in some instances have been reported to be ineffective under commercial conditions (Dawson and Stadelman, 1960). Recently, Dawson et al. (1963) showed that the inhibitory effect of chlortetracycline was improved by combining it with surface pasteurization. The ideal preservative, one that would control undesirable change in color, odor, and taste, and be harmless to the consumer, has not been discovered. Foods 1 Scientific Paper No. 2406, Washington Agricultural Experiment Stations, Pullman. Project No. 1272.

such as vanilla and lemon flavoring extracts are preserved by their ethanol content. Ethanol is germicidal in concentrations between 50 and 70% and is antiseptic at higher and lower concentrations. Hall and Spencer (1960) demonstrated that ethanol was effective as a preservative for poultry meat. The purpose of this study was to further investigate the effectiveness of ethanol as a preservative and to determine whether or not it would influence the flavor of chicken meat. PROCEDURE

Fourteen-week-old chickens were killed by severing the jugular veins and carotid arteries, bled for one minute, scalded at 60°C. for 40 seconds and machine picked. They were warm eviscerated and chilled 2.5 hours in slush ice. After chilling, the carcasses were drained, placed in polyethylene bags, frozen and stored at 29°C. until used. Following storage, the frozen chickens were sawed into halves, placed in polyethylene bags, and allowed

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1964. Increase in pullet egg size with age. Poultry Sci. 43: 482-486. Dempster, E. R., and I. M. Lerner, 1947. The optimum structure of breeding flocks. 1. The rate of genetic improvement under different breeding plans. Genetics, 32: 555-566. Godfrey, A. B., 1933. Methods of estimating the mean egg weight per bird for the first year production. Poultry Sci. 12: 368-372. Kempthorne, 0., 1952. The Design and Analysis of Experiments. John Wiley and Sons, Inc., New York. First ed., pp. 38-67. King, S. C , and C. R. Henderson, 1954. Heritability studies of egg production in the domestic fowl.

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The effect of ethanol upon flavor of chickens was evaluated, using samples that had been held refrigerated four days after treatment. The ethanol-dipped and control halves were coated with saturated vegetable shortening (Crisco), individually wrapped in aluminum foil and cooked in separate ovens at 226°C. for one hour. To allow skin to brown, the foil

was removed after 40 minutes of cooking. Portions of skin, dark meat, and white meat were sliced into bite size pieces wrapped in aluminum foil and coded. In paired comparisons, each sample from the ethanol-dipped half was compared with the corresponding sample from the control half of the same chicken. Six individuals with sensory panel experience tasted six sets of paired comparisons at each of four sessions. Two ethanol-dipped halves were compared with their control halves at each session. The presentation of the sample was completely randomized without duplications. The panelists were asked to indicate which sample in the paired comparison had a more typical chicken flavor and whether or not each sample was acceptable. They were also requested to describe any observed flavor differences. The level of significance of differences noted in the flavor study was determined by using a table of probabilities for 50% chance (Krum, 1955). RESULTS AND DISCUSSION

The average microbial counts of ethanoldipped and control halves are plotted in Figure 1. Eleven days were required for the controls to reach a microbial count of 1X10 7 sq. cm., while the ethanoldipped halves required 14 days. A bacterial count of approximately 1X10 7 per sq. cm. has been suggested as indicative of spoilage (Dawson and Stadelman, 1960). The log phase of growth was extended a day or more. The mean microbial counts per sq. cm. are shown with the 95% confidence interval in Table 1. Microbial counts of the ethanol-dipped halves were lower than their respective controls in all cases, except three halves counted within one hour after dipping. It was the opinion of the writers that the two halves of each chicken initially had the same microbial count, and within one hour of storage the

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to thaw in a refrigerator at 1°C. for 48 hours. In an attempt to obtain a more uniform microbial count, the chicken halves were immersed for 10 minutes in agitated tap water at 24°C. After draining for five minutes, one-half of each chicken was immersed for 30 seconds in 70% ethanol at room temperature. The ethanol dip was prepared by an appropriate dilution of 95% ethanol (U.S.P.). Control halves were immersed for 30 seconds in distilled water. After treatment, each half was drained for five minutes, individually placed on a paperboard tray, enclosed in a polyethylene bag, and stored at 1°C. A total of 20 ethanol dipped and 20 control halves were used in four replications of this study. Ultraviolet fluorescence, off-odor, and slime smear (Ziegler et al., 1954) were used to determine spoilage. Total microbial counts were obtained from a swabbing of the breast skin outlined by a one square inch template. These values were later converted to microbial counts per square centimeter. Swabbing was done within one hour after dipping and again after 6, 12, and 15 days storage. Since successive swabbings of the same area of breast skin had reduced the microbial count in preliminary studies, adjacent areas were used. Swabs were immediately suspended in isotonic saline dilution blanks. One milliliter aliquots of each dilution were placed in duplicate petri dishes, poured with Tryptone Glucose Extract Agar and incubated at 25°C. for 48 hours.

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ETHANOL AND CHICKEN MEAT

ethanol dip had already reduced the number of viable microorganisms. This difference in count increased up to about six days of storage. Although the microbial count on the sixth day for the untreated carcasses was considerably higher, the rate of increase thereafter was relatively constant for both groups. When the test criteria of spoilage were ultraviolet fluorescence, off-odor and slime smear, the control halves were all spoiled by 10 to 11 days. Only 3, 2 and 7 ethanol-dipped halves were spoiled by the fifteenth day

when measured by ultraviolet fluorescence, off-odor and slime smear, respectively. TABLE 1.—The effect of ethanol on mean microbial counts per sq. cm. Mean microbial counts 1

Time af ter dipping

Number of halves

Ethanol-dipped

Control

1 hour 6 days 12 days 15 days

20 10 15 10

95 + 61 (29 + 11)10! (62 + 63)10* (50+ 63) 10s

(19 + 8)10 l (58 + 22)102 (65±10)10 6

95% confidence interval given with means.

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FIG. 1. The effect of ethanol on the microbial counts of tray-packed chicken halves.

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TABLE 2.—More typical chicken flavor in 48 paired comparisons of skin, white meat and dark meat More chicken flavor Ethanoldipped Skin White meat Dark meat

15 6 11

^

. ,

Contro1

33 42 37

Level of significance P<0.01 P<0.01 P<0.01

SUMMARY

A 70% ethanol dip increased the shelflife of tray packaged chicken halves by three to five days. Control halves were characterized as having more typical

ACKNOWLEDGMENTS Appreciation is expressed to the Department of Home Economics for the use of the taste panel facilities and to Margaret M. Weller for assistance in perparing the samples and conducting the panels. REFERENCES Dawson, L. E., W. L. Mallmann, D. G. Bigbee, R. Walker and M. E. Zabik, 1963. Influence of surface pasteurization and chlortetracycline on bacterial incidence on fryers. Food Tech. 17:218-221. Dawson, L. E., and W. J. Stadelman, 1960. Microorganisms and their control on fresh poultry meat. North Central Reg. Pub. 112, Michigan State Univ. Agr. Expt. Sta. Tech. Bull. 278. Hall, K. N., and J. V. Spencer, 1960. Effects of ethanol upon the shelf-life of chicken fryers. Poultry Sci. 39: 1256-1257. Krum, J. K., 1955. Truest evaluations in sensory panel testing. Food Engr. 27 (7): 74-83. Spencer, J. V., E. A. Sauter and W. J. Stadelman, 1961. Effect of freezing, thawing and storing broilers on spoilage, flavor and bone darkening. Poultry Sci. 40: 918-920. Ziegler, F., J. V. Spencer and W. J. Stadelman, 1954. A rapid method for determining spoilage in fresh poultry meat. Poultry Sci. 33: 1253-1255.

NEWS AND NOTES ERRATUM There were two manuscript errors in the article entitled "Labile Methyl Group Biosynthesis in the Turkey Poult. 2. Effects of dietary methionine, choline and vitamin B12 on liver phospholipid dimethylethanolamine," published in the January issue of Poultry Science, pages 135-138. In Table 1, page 137, the heading "Dimethylethanolamine (mg./kg.) phospholipid," should read "Dimethylethanolamine Qig./ng.) phospholipid."

On page 136, 2nd column, line 31, reading "as pg DMEA per pg. phospholipid" should read as ng. DMEA per ng. phospholipid." ERRATUM There was a manuscript error in the article entitled "In vitro uptake of Fe59 in adult and immature avian and human red cells" by R. P. Reckel and S. L. Scheinberg, pages 595-598 of the May, 1963, issue of Poultry Science. The word "tritium" should not have appeared in the legend of Figures 1 and 2.

{Continued on page 599)

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Table 2 shows that the control halves had a more typical chicken flavor when skin, white meat, or dark meat were tasted (P<0.01). In 48 paired comparisons, the skin, white meat and dark meat of control chickens were acceptable by the taste panel in 75, 94 and 96% of the observations, respectively. For the ethanoldipped halves the corresponding values were 65, 77 and 79 percent. The descriptions most commonly used to characterize the flavor difference between samples were strong, rancid and medicinal. Included in the 144 paired comparisons, there were 23 objections to the flavor of the controls while there were 84 objections to the flavor of ethanol-dipped halves.

chicken flavor than ethanol-dipped halves when paired comparisons of either skin, white meat or dark meat were made. Ethanol-dipped halves were considered unacceptable more frequently than control halves.