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The Effect of Feather Removal During Processing on the Xanthophyll Content of Broiler Skin1
CALCIUM AND Y O L K MOTTLING
General observations. Poultry Sci. 25: 440-445. Sherwood, R. M., 1931a. The effect of various rations on the storage quality of eggs. Texas Agr. Expt. Sta. Bull. 376: 1-12. Sherwood, R. M., 1931b. The effect of cottonseed meal and other feeds on the storage quality of eggs. Texas Agr. Expt. Sta. Bull. 429: 1-19. Silvestrini, D. A., L. E. Dawson, R. J. Evans and J. A. Davidson, 1965. Effects of nicarbazin in diet on mottled yolks. 2. Incidence and degree of mottling, and certain yolk proteins. Poultry Sci. 44: 467-473. Taylor, T. G., 1970. How an eggshell is made. Sci. American, 222: 88-95. Van Tienhoven, A., F. W. Hill, A. Prock and R. C. Baker, 1958. The effect of nicarbazin on yolk quality. Poultry Sci. 37: 129-132. Withers, W. A., and F. E. Carruth, 1915. Gossypol the toxic substance in cottonseed meal. J. Agr. Res. 5: 261-288.
The Effect of Feather Removal During Processing on the Xanthophyll Content of Broiler Skin1 J. L . H E A T H AND O. P . THOMAS
Department of Poultry Science, University of Maryland, College Park, Maryland 20742 (Received for publication May 14, 1973)
ABSTRACT Three experiments were conducted to study the influence of mechanical feather removal on the xanthophyll content of broiler breast skin and feather tract. A reduction in the amount of xanthophyll in the breast skin and feather tract occurred when the birds were scalded and picked. The largest decrease occurred after scalding when the skin was considered and after picking when the feather tract was examined. The skin had a larger amount of xanthophyll per 100 cm.2 following picking than was present after scalding. Exposing the carcasses to the scald water for 60, 120 or 180 seconds resulted in no changes in xanthophyll content of either the breast skin or feather tract. When the carcasses were exposed for 60 or 90 seconds in another experiment, an increase in xanthophyll per 100 cm.2 of breast skin was found to occur as the scald time was increased. A decrease in the amount of xanthophyll per 100 cm.2 was noticed to occur after picking for either 20, 40,-60 or 80 seconds when scalded for 60 or 90 seconds. The xanthophyll per 100 cm.2 of feather tract decreased when picked after being scalded for 90 seconds. POULTRY SCIENCE 53: 291-295, 1974
INTRODUCTION
I
N a previous paper, Heath and Thomas (1973), it was reported that a decrease in xanthophyll content of both the skin and 1. Scientific Article No. A1897, Contribution No. 4813 of the Maryland Agricultural Experiment Station (Department of Poultry Science).
feather tract occurred as the scald temperature was increased from 50 to 56° C. It was also determined that the exposure of the carcass to scald water for 30, 45, 60 and 75 seconds resulted in a reduction in the amount of xanthophyll per cm. 2 of skin as time increased. When the xanthophyll content was expressed as per gram of tissue no
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 9, 2015
tions. Biometrics, 12: 307-310. McCready, S. T., and D. A. Roland, Sr., 1972. Unpublished data. Florida Agr. Exp. Sta. Menazel, J., and A. Harell, 1971. Calcified Tissue, Structural, Functional and Metabolic Aspects. Academic Press, Inc. 111 5th Avenue, N.Y., N.Y. 10003 p. 51. Phelps, R. A., F. S. Shenstone, A. R. Kemmerer and R. J. Evans, 1965. A review of cyclopropenoid compounds; Biological effects of some derivatives. Poultry Sci. 44: 358-394. Polin, D., W. H. Ott and A. Zeissig, 1958. Field studies on the effect of nicarbazin on egg quality. Poultry Sci. 37: 898-913. Roland, D. A., Sr., D. R. Sloan and R. H. Harms, 1972. Yolk mottling associated with dietary calcium deficiency. Poultry Sci. 51: 710-712. Schaible, P. J., S. L. Bandemer and J. A. Davidson, 1946. Composition of fresh and storage eggs from hens fed cottonseed and non-cottonseed rations. 1.
291
292
J. L. HEATH AND O. P. THOMAS
differences were found. This paper also reviewed the work of other researchers who have reported alteration in the appearance and stability of the skin due to the feather removal process (Klose et al., 1961; Mountney, 1966; Parnell et al., 1950; Pearce and Lavers, 1949; Pool et al., 1954). This research was designed to investigate further the influence of time of exposure to the scald water and to determine the effect of picking on the xanthophyll content of broiler skin and feather tract.
The birds used in these experiments were reared at the Poultry Department Experimental Farm in a well lighted and ventilated house. A corn-soybean diet which had sufficient xanthophyll to produce a uniformly pigmented carcass was fed. The feed contained recommended levels of a cocidiostat to prevent variation in pigmentation due to coccidiosis. At 8 weeks of age the birds were transported to the Poultry Departments' processing facility. Scalding and picking were accomplished in a Barker Scalder Model CSC and a Barker Cyclomatic Picker Model CPC. This equipment allowed 5 birds to be killed, scalded, moved directly to the picker at completion of scalding and picked with no delay in the operation. Experiment I. One-hundred-fifty broilers were used to determine the influence of mechanical feather removal on the xanthophyll content of the breast skin and feather tract. A sample of breast skin and feather tract was removed from each bird at one of three stages of feather removal. The area termed breast skin was adjacent and attached to the feather tract (pterylae) sample. The breast skin area has relatively few feather follicles whereas the feather tract is the area where most of the follicles are located (Card and Nesheim, 1966). The samples were removed from a point midway the length of
Experiment 2. One-hundred-fifty broilers were used to determine if the duration of exposure to the scald water had an effect on the xanthophyll content of breast skin and feather tract. The birds were bled, scalded at 55° C. for either 60, 120 or 180 seconds and picked for 60 seconds. A sample of breast skin and feather tract was removed prior to evisceration from each bird in the same manner as in experiment 1, placed in a plastic bag and stored in the dark at - 5 ° C. Experiment 3. Four-hundred-eighty broilers were used to study the effect of picking and scalding for varying lengths of time on the xanthophyll content of the breast skin and feather tract. The birds were bled, scalded at 53° C. for either 60 or 90 seconds and picked for either 20, 40, 60 or 80 seconds. A sample of breast skin and feather tract was removed and stored in the same manner as the previous two experiments. Xanthophyll Extraction and Determination. The samples were removed from the freezer and allowed to thaw for one hour at room temperature. Moisture was removed from the tissue surface by gently pressing between paper towels. A portion of the sample was measured to determine the surface area, weighed, chopped into small pieces and extracted in 20 ml. acetone per gram of sample. The samples were extracted for 72 hours in the dark prior to being washed from the extraction bottles onto a column of anhy-
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 9, 2015
EXPERIMENTAL PROCEDURE
the feather tract at a point where the cuticle remained intact. After a sample was removed, the breast skin and feather tract was separated. The first group was sampled after bleeding, the second after scalding for 60 seconds at 53° C. and the third after the birds were picked for 60 seconds. The breast skin and feather tract samples were placed in plastic bags and stored in the dark at - 5 ° C. until analysis could be accomplished.
293
FEATHER REMOVAL AND SKIN XANTHOPHYLL
drous sodium sulfate. The eluent was collected and the absorbancy determined in a Coleman Model 14 spectrophotometer at 475 mfx. using acetone as the blank. The resulting quantities were expressed as meg. of xanthophyll per 100 cm. 2 of skin or feather tract and per gram of tissue. Statistical Analysis. The data were analyzed using the analysis of variance technique of Steel and Torrie (1960). RESULTS AND DISCUSSION
TABLE 1.—The effect of feather removal on the xanthophyll Content of the breast skin and feather tract Feather tract
Skin Samples taken after Bleeding Scalding Picking
meg./100 cm. 2 Trial 1* 2* 74.9a 50.7b 62.2c
67.2a 50.2b 56.4b
meg./gm. Trial 1 2 8.0 7.8 7.4
9.2 8.8 8.1
meg./100 cm. 2 Trial j** 2** 188.5a 187.2a 131.0b
201.5a 200.3a 147.5b
meg. /gm. Trial 1* 2* 4.5a 4.7a 4.3a 4.5a 3.6b 3.9b
**Means in columns followed by different letters are significantly different (P s 0.01). *Means in columns followed by different letters are significantly different (P £ 0.05).
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 9, 2015
Experiment 1. A reduction of xanthophyll in the breast skin and feather tract occurred as the birds were scalded and picked (Table 1). A significant (P s 0.05) difference was found for both trials 1 and 2 when the xanthophyll content of the breast skin was expressed as meg. /100 cm. 2 The xanthophyll content of the skin after scalding or picking was less than that sampled after being bled, and was larger after picking than after scalding. The decrease after scalding could be a result of the temperature of the scald water. This corresponded to data reported in a previous paper (Heath and Thomas, 1973) in which a decrease was noticed to occur as the scald temperature was increased. The increase in xanthophyll content after picking when compared to skin samples after scalding could result from the disruption of the skin during picking and the subsequent shrinkage as the skin cools. This would be noticed when the xanthophyll content was expressed on the surface area basis. No significant dif-
ferences were found when the xanthophyll content of the breast skin was expressed as per gram of tissue. This could be a result of the skin picking up and retaining varying amounts of scald water resulting in increased variation to the extent of not detecting significant differences. A significant (P ^ 0.01) reduction in xanthophyll content of the breast feather tract occurred when expressed as meg./100 cm. 2 and a significant (P s 0.05) reduction when expressed as per gram of tissue after scalding and picking (Table 1). This differed from the skin where significant differences were found only when expressed as meg./100 cm. 2 The xanthophyll content of the breast feather tract decreased the most after the birds were picked following scalding. This was different from what was found in the skin where the largest decrease occurred after scalding followed by an increase after picking. This could be explained by the following. The feather tract samples included not only the feather tract but also the lipid underlying the feather tract. This lipid contained substantial amounts of xanthophyll. The scalding operation could be expected to remove xanthophyll from the surface but not have as much effect on the xanthophyll underlying the feather tract in the lipid portion. Therefore, the same amount of xanthophyll could be removed from the surface of the feather tract as from the skin but would not be a significant loss because of the large amount in the underlying lipid. This same reasoning could explain the finding of significance when the xanthophyll
294
J. L. HEATH AND O. P. THOMAS
TABLE 2.-
-The influence of length of time of exposure to scald water on the xanthophyll content of breast skin and feather tract. Ski n
Scald time (seconds) 60 120 180
meg./100 cm. 2 Trial 1 Trial 2 13.8 12.1 14.8
10.6 10.1 10.4
Feather tract
meg./gm. Trial 1 Trial 2 4.1 3.3 4.1
3.7 4.7 4.4
meg./100 cm. 2 Trial 1 Trial 2 74.1 77.1 75.8
71.0 72.8 74.9
meg. /gm. Trial 1 Trial 2 3.2 3.7 3.5
3.0 3.3 3.3
Scalded at 55° C. and picked for 60 seconds.
Experiment 2. Increasing the length of time the carcasses were exposed to the scald water from 60 to 120 to 180 seconds had no influence on the xanthophyll content of breast skin or feather tract (Table 2). Significant decreases in xanthophyll content were found in a previous study (Heath and Thomas, 1973) when the xanthophyll was expressed as meg. /100 cm. 2 The time of exposure to the scald water, 30-75 seconds, was substantially less and the birds were scalded at a lower temperature
TABLE 3.
(53° C.) than in this experiment. This could indicate a time x temperature effect that could be important in determining scald conditions to maintain a desirable xanthophyll level in the skin. Experiment 3. A significant (P s 0.01) decrease in the meg. of xanthophyll per 100 cm. 2 of skin was found as the pick time increased after the carcasses were scalded for either 60 or 9Q seconds (Table 3). No significant differences were found when the xanthophyll content of the skin was expressed as meg. /gm. Essentially all the feathers were removed during each treatment. The feather tract had significant (P < 0.05) decreases in meg. of xanthophyll per 100 cm. 2 when the birds were picked after being scalded for 90 seconds (Table 4). No significant differences were found attributable to picking after scalding for 60 seconds or when the xanthophyll was expressed as meg./gm. after scalding for either 60 or 90 seconds. The finding of significant differences for the longer scald times could have resulted from
-The xanthophyll content of the breast skin after the carcasses were picked following scalding for 60 or 90 seconds at 55" C. 60 Second scald1
Pick time (seconds) 20 40 60 80
2
meg. /100 cm. Trial 1** Trial 2** 24.0a 22.4ab 19.5ab 20.9ab
25.2a 20.2b 21.2b 21.1b
90 Second scald 1
meg. /gm. Trial 1 Trial 2 2.8 2.8 2.7 3.0
2.6 2.6 2.4 3.2
meg./100 cm. 2 Trial 1** Trial 2** 26.6a 25.9a 25.5a 21.5b
24.9a 24.0a 23.5a 19.6b
meg,./gm. Trial 2 Trial 1 3.4 3.3 3.5 3.1
'The two scald times resulted in significant differences (P s 0.05) **Means in columns followed by different letters are significantly different (P =£ 0.01).
2.9 3.1 3.3 2.4
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 9, 2015
was expressed as meg./gm. of tissue. The amount of scald water absorbed would have less influence on the weight of the sample because of the large amount of lipid associated with this tissue. The picking operation could be expected to influence the feather tract to a greater degree than the skin. The force applied by the picking fingers to the skin and the extraction of feathers could result in disruption of the lipid structure under the surface. This could especially be true after it was softened as a result of the temperature of scald.
FEATHER REMOVAL AND SKIN XANTHOPHYLL
295
TABLE 4.—The xanthophyll content of the breast feather tract after the carcasses were picked following scalding for 60 or 90 seconds at 55" C. 90 Second scald 60 Second scald meg.,/gm. meg./100 cm. 2 meg,,/gm. meg./100 cm. 2 Pick time Trial 2 Trial 2 Trial 1* Trial 2* Trial 1 Trial 1 Trial 1 Trial 2 (seconds) 2.8 3.0 115.8a 117.3a 2.6 2.4 80.3 81.0 20 2.7 2.7 117.2a 99.7ab 2.4 2.4 77.7 94.0 40 2.9 2.5 80.2b 88.8b 2.2 2.6 76.6 88.0 60 2.5 2.0 76.6b 83.3b 2.7 2.6 107.2 94.2 80 *Means in columns followed by different letters are significantly different (P =s 0.05).
ACKNOWLEDGEMENTS The assistance of Cheryl Korman, Celeste Maiorana, and Andrea Reding in the collection, preparation and analysis of the samples is greatly appreciated. REFERENCES Card, L. E., and M. C. Nesheim, 1966. Poultry Production, Lee and Febiger, Philadelphia, Penn. Heath, J. L., and O. P. Thomas, 1973. The xanthophyll content and color of broiler skin after scalding. Poultry Sci. 52: 967-971. Klose, A. A., E. P. Mecchi and M. F. Pool, 1961. Observations on factors influencing feather release. Poultry Sci. 40: 1029-1036. Mountney, G. J., 1966. Poultry Products Technology. The Avi Publishing Co., Inc., Westport, Conn. Parnell.E.D.,O.D.Butler andS.Cover, 1950. Storage tests with unwrapped frozen fryers. Texas Agric. Exp. Sta. Progress Rept. 1270. Pearce, J. A., and C. G. Lavers, 1949. Frozen storage of poultry. V. Effects of some processing factors on quality. Canadian J. Research, 27: 253-265. Pool, M. F., E. P. Mecchi, H. Lineweaver and A. A. Klose, 1954. The effect of scalding temperature on the processing and initial appearance of turkeys. Poultry Sci., 33: 274-279. Steel, R. F. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Book Company, Inc., New York.
AUGUST 19-23, 1974. THE IV INTERNATIONAL SYMPOSIUM ON RUMINANT PHYSIOLOGY, SYDNEY, AUSTRALIA.
SEPTEMBER 22-27, 1974. IV INTERNATIONAL CONGRESS OF FOOD SCIENCE AND TECHNOLOGY, MADRID, SPAIN.
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 9, 2015
the lipid underlying the feather tract becoming more soft and facilitating removal and/or dispersion of the xanthophyll containing lipid. This experiment demonstrated that the pick time did have an effect on the xanthophyll content of the broiler carcass and this effect was influenced by the scalding conditions of the experiment. The two scald times were selected to fall between those of experiment 2 and those mentioned as previous work in experiment 2 in an attempt to determine the effect of scald time on xanthophyll content. A significant (P =£ 0.05) increase in the xanthophylll content of the breast skin was found as the scald time was increased from 60 to 90 seconds. This could be due to the feathers being loosened to a greater degree at 90 seconds of scald than at 60 seconds resulting in less skin damage. No significant differences were found when the xanthophyll content of the feather tract was examined. This research indicated that scald times less than 90 seconds had an influence on xanthophyll content of the skin but when increased above 90 seconds there were no significant differences found attributable to scald time.
General observations. Poultry Sci. 25: 440-445. Sherwood, R. M., 1931a. The effect of various rations on the storage quality of eggs. Texas Agr. Expt. Sta. Bull. 376: 1-12. Sherwood, R. M., 1931b. The effect of cottonseed meal and other feeds on the storage quality of eggs. Texas Agr. Expt. Sta. Bull. 429: 1-19. Silvestrini, D. A., L. E. Dawson, R. J. Evans and J. A. Davidson, 1965. Effects of nicarbazin in diet on mottled yolks. 2. Incidence and degree of mottling, and certain yolk proteins. Poultry Sci. 44: 467-473. Taylor, T. G., 1970. How an eggshell is made. Sci. American, 222: 88-95. Van Tienhoven, A., F. W. Hill, A. Prock and R. C. Baker, 1958. The effect of nicarbazin on yolk quality. Poultry Sci. 37: 129-132. Withers, W. A., and F. E. Carruth, 1915. Gossypol the toxic substance in cottonseed meal. J. Agr. Res. 5: 261-288.
The Effect of Feather Removal During Processing on the Xanthophyll Content of Broiler Skin1 J. L . H E A T H AND O. P . THOMAS
Department of Poultry Science, University of Maryland, College Park, Maryland 20742 (Received for publication May 14, 1973)
ABSTRACT Three experiments were conducted to study the influence of mechanical feather removal on the xanthophyll content of broiler breast skin and feather tract. A reduction in the amount of xanthophyll in the breast skin and feather tract occurred when the birds were scalded and picked. The largest decrease occurred after scalding when the skin was considered and after picking when the feather tract was examined. The skin had a larger amount of xanthophyll per 100 cm.2 following picking than was present after scalding. Exposing the carcasses to the scald water for 60, 120 or 180 seconds resulted in no changes in xanthophyll content of either the breast skin or feather tract. When the carcasses were exposed for 60 or 90 seconds in another experiment, an increase in xanthophyll per 100 cm.2 of breast skin was found to occur as the scald time was increased. A decrease in the amount of xanthophyll per 100 cm.2 was noticed to occur after picking for either 20, 40,-60 or 80 seconds when scalded for 60 or 90 seconds. The xanthophyll per 100 cm.2 of feather tract decreased when picked after being scalded for 90 seconds. POULTRY SCIENCE 53: 291-295, 1974
INTRODUCTION
I
N a previous paper, Heath and Thomas (1973), it was reported that a decrease in xanthophyll content of both the skin and 1. Scientific Article No. A1897, Contribution No. 4813 of the Maryland Agricultural Experiment Station (Department of Poultry Science).
feather tract occurred as the scald temperature was increased from 50 to 56° C. It was also determined that the exposure of the carcass to scald water for 30, 45, 60 and 75 seconds resulted in a reduction in the amount of xanthophyll per cm. 2 of skin as time increased. When the xanthophyll content was expressed as per gram of tissue no
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 9, 2015
tions. Biometrics, 12: 307-310. McCready, S. T., and D. A. Roland, Sr., 1972. Unpublished data. Florida Agr. Exp. Sta. Menazel, J., and A. Harell, 1971. Calcified Tissue, Structural, Functional and Metabolic Aspects. Academic Press, Inc. 111 5th Avenue, N.Y., N.Y. 10003 p. 51. Phelps, R. A., F. S. Shenstone, A. R. Kemmerer and R. J. Evans, 1965. A review of cyclopropenoid compounds; Biological effects of some derivatives. Poultry Sci. 44: 358-394. Polin, D., W. H. Ott and A. Zeissig, 1958. Field studies on the effect of nicarbazin on egg quality. Poultry Sci. 37: 898-913. Roland, D. A., Sr., D. R. Sloan and R. H. Harms, 1972. Yolk mottling associated with dietary calcium deficiency. Poultry Sci. 51: 710-712. Schaible, P. J., S. L. Bandemer and J. A. Davidson, 1946. Composition of fresh and storage eggs from hens fed cottonseed and non-cottonseed rations. 1.
291
292
J. L. HEATH AND O. P. THOMAS
differences were found. This paper also reviewed the work of other researchers who have reported alteration in the appearance and stability of the skin due to the feather removal process (Klose et al., 1961; Mountney, 1966; Parnell et al., 1950; Pearce and Lavers, 1949; Pool et al., 1954). This research was designed to investigate further the influence of time of exposure to the scald water and to determine the effect of picking on the xanthophyll content of broiler skin and feather tract.
The birds used in these experiments were reared at the Poultry Department Experimental Farm in a well lighted and ventilated house. A corn-soybean diet which had sufficient xanthophyll to produce a uniformly pigmented carcass was fed. The feed contained recommended levels of a cocidiostat to prevent variation in pigmentation due to coccidiosis. At 8 weeks of age the birds were transported to the Poultry Departments' processing facility. Scalding and picking were accomplished in a Barker Scalder Model CSC and a Barker Cyclomatic Picker Model CPC. This equipment allowed 5 birds to be killed, scalded, moved directly to the picker at completion of scalding and picked with no delay in the operation. Experiment I. One-hundred-fifty broilers were used to determine the influence of mechanical feather removal on the xanthophyll content of the breast skin and feather tract. A sample of breast skin and feather tract was removed from each bird at one of three stages of feather removal. The area termed breast skin was adjacent and attached to the feather tract (pterylae) sample. The breast skin area has relatively few feather follicles whereas the feather tract is the area where most of the follicles are located (Card and Nesheim, 1966). The samples were removed from a point midway the length of
Experiment 2. One-hundred-fifty broilers were used to determine if the duration of exposure to the scald water had an effect on the xanthophyll content of breast skin and feather tract. The birds were bled, scalded at 55° C. for either 60, 120 or 180 seconds and picked for 60 seconds. A sample of breast skin and feather tract was removed prior to evisceration from each bird in the same manner as in experiment 1, placed in a plastic bag and stored in the dark at - 5 ° C. Experiment 3. Four-hundred-eighty broilers were used to study the effect of picking and scalding for varying lengths of time on the xanthophyll content of the breast skin and feather tract. The birds were bled, scalded at 53° C. for either 60 or 90 seconds and picked for either 20, 40, 60 or 80 seconds. A sample of breast skin and feather tract was removed and stored in the same manner as the previous two experiments. Xanthophyll Extraction and Determination. The samples were removed from the freezer and allowed to thaw for one hour at room temperature. Moisture was removed from the tissue surface by gently pressing between paper towels. A portion of the sample was measured to determine the surface area, weighed, chopped into small pieces and extracted in 20 ml. acetone per gram of sample. The samples were extracted for 72 hours in the dark prior to being washed from the extraction bottles onto a column of anhy-
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 9, 2015
EXPERIMENTAL PROCEDURE
the feather tract at a point where the cuticle remained intact. After a sample was removed, the breast skin and feather tract was separated. The first group was sampled after bleeding, the second after scalding for 60 seconds at 53° C. and the third after the birds were picked for 60 seconds. The breast skin and feather tract samples were placed in plastic bags and stored in the dark at - 5 ° C. until analysis could be accomplished.
293
FEATHER REMOVAL AND SKIN XANTHOPHYLL
drous sodium sulfate. The eluent was collected and the absorbancy determined in a Coleman Model 14 spectrophotometer at 475 mfx. using acetone as the blank. The resulting quantities were expressed as meg. of xanthophyll per 100 cm. 2 of skin or feather tract and per gram of tissue. Statistical Analysis. The data were analyzed using the analysis of variance technique of Steel and Torrie (1960). RESULTS AND DISCUSSION
TABLE 1.—The effect of feather removal on the xanthophyll Content of the breast skin and feather tract Feather tract
Skin Samples taken after Bleeding Scalding Picking
meg./100 cm. 2 Trial 1* 2* 74.9a 50.7b 62.2c
67.2a 50.2b 56.4b
meg./gm. Trial 1 2 8.0 7.8 7.4
9.2 8.8 8.1
meg./100 cm. 2 Trial j** 2** 188.5a 187.2a 131.0b
201.5a 200.3a 147.5b
meg. /gm. Trial 1* 2* 4.5a 4.7a 4.3a 4.5a 3.6b 3.9b
**Means in columns followed by different letters are significantly different (P s 0.01). *Means in columns followed by different letters are significantly different (P £ 0.05).
Downloaded from http://ps.oxfordjournals.org/ at New York University on June 9, 2015
Experiment 1. A reduction of xanthophyll in the breast skin and feather tract occurred as the birds were scalded and picked (Table 1). A significant (P s 0.05) difference was found for both trials 1 and 2 when the xanthophyll content of the breast skin was expressed as meg. /100 cm. 2 The xanthophyll content of the skin after scalding or picking was less than that sampled after being bled, and was larger after picking than after scalding. The decrease after scalding could be a result of the temperature of the scald water. This corresponded to data reported in a previous paper (Heath and Thomas, 1973) in which a decrease was noticed to occur as the scald temperature was increased. The increase in xanthophyll content after picking when compared to skin samples after scalding could result from the disruption of the skin during picking and the subsequent shrinkage as the skin cools. This would be noticed when the xanthophyll content was expressed on the surface area basis. No significant dif-
ferences were found when the xanthophyll content of the breast skin was expressed as per gram of tissue. This could be a result of the skin picking up and retaining varying amounts of scald water resulting in increased variation to the extent of not detecting significant differences. A significant (P ^ 0.01) reduction in xanthophyll content of the breast feather tract occurred when expressed as meg./100 cm. 2 and a significant (P s 0.05) reduction when expressed as per gram of tissue after scalding and picking (Table 1). This differed from the skin where significant differences were found only when expressed as meg./100 cm. 2 The xanthophyll content of the breast feather tract decreased the most after the birds were picked following scalding. This was different from what was found in the skin where the largest decrease occurred after scalding followed by an increase after picking. This could be explained by the following. The feather tract samples included not only the feather tract but also the lipid underlying the feather tract. This lipid contained substantial amounts of xanthophyll. The scalding operation could be expected to remove xanthophyll from the surface but not have as much effect on the xanthophyll underlying the feather tract in the lipid portion. Therefore, the same amount of xanthophyll could be removed from the surface of the feather tract as from the skin but would not be a significant loss because of the large amount in the underlying lipid. This same reasoning could explain the finding of significance when the xanthophyll
294
J. L. HEATH AND O. P. THOMAS
TABLE 2.-
-The influence of length of time of exposure to scald water on the xanthophyll content of breast skin and feather tract. Ski n
Scald time (seconds) 60 120 180
meg./100 cm. 2 Trial 1 Trial 2 13.8 12.1 14.8
10.6 10.1 10.4
Feather tract
meg./gm. Trial 1 Trial 2 4.1 3.3 4.1
3.7 4.7 4.4
meg./100 cm. 2 Trial 1 Trial 2 74.1 77.1 75.8
71.0 72.8 74.9
meg. /gm. Trial 1 Trial 2 3.2 3.7 3.5
3.0 3.3 3.3
Scalded at 55° C. and picked for 60 seconds.
Experiment 2. Increasing the length of time the carcasses were exposed to the scald water from 60 to 120 to 180 seconds had no influence on the xanthophyll content of breast skin or feather tract (Table 2). Significant decreases in xanthophyll content were found in a previous study (Heath and Thomas, 1973) when the xanthophyll was expressed as meg. /100 cm. 2 The time of exposure to the scald water, 30-75 seconds, was substantially less and the birds were scalded at a lower temperature
TABLE 3.
(53° C.) than in this experiment. This could indicate a time x temperature effect that could be important in determining scald conditions to maintain a desirable xanthophyll level in the skin. Experiment 3. A significant (P s 0.01) decrease in the meg. of xanthophyll per 100 cm. 2 of skin was found as the pick time increased after the carcasses were scalded for either 60 or 9Q seconds (Table 3). No significant differences were found when the xanthophyll content of the skin was expressed as meg. /gm. Essentially all the feathers were removed during each treatment. The feather tract had significant (P < 0.05) decreases in meg. of xanthophyll per 100 cm. 2 when the birds were picked after being scalded for 90 seconds (Table 4). No significant differences were found attributable to picking after scalding for 60 seconds or when the xanthophyll was expressed as meg./gm. after scalding for either 60 or 90 seconds. The finding of significant differences for the longer scald times could have resulted from
-The xanthophyll content of the breast skin after the carcasses were picked following scalding for 60 or 90 seconds at 55" C. 60 Second scald1
Pick time (seconds) 20 40 60 80
2
meg. /100 cm. Trial 1** Trial 2** 24.0a 22.4ab 19.5ab 20.9ab
25.2a 20.2b 21.2b 21.1b
90 Second scald 1
meg. /gm. Trial 1 Trial 2 2.8 2.8 2.7 3.0
2.6 2.6 2.4 3.2
meg./100 cm. 2 Trial 1** Trial 2** 26.6a 25.9a 25.5a 21.5b
24.9a 24.0a 23.5a 19.6b
meg,./gm. Trial 2 Trial 1 3.4 3.3 3.5 3.1
'The two scald times resulted in significant differences (P s 0.05) **Means in columns followed by different letters are significantly different (P =£ 0.01).
2.9 3.1 3.3 2.4
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was expressed as meg./gm. of tissue. The amount of scald water absorbed would have less influence on the weight of the sample because of the large amount of lipid associated with this tissue. The picking operation could be expected to influence the feather tract to a greater degree than the skin. The force applied by the picking fingers to the skin and the extraction of feathers could result in disruption of the lipid structure under the surface. This could especially be true after it was softened as a result of the temperature of scald.
FEATHER REMOVAL AND SKIN XANTHOPHYLL
295
TABLE 4.—The xanthophyll content of the breast feather tract after the carcasses were picked following scalding for 60 or 90 seconds at 55" C. 90 Second scald 60 Second scald meg.,/gm. meg./100 cm. 2 meg,,/gm. meg./100 cm. 2 Pick time Trial 2 Trial 2 Trial 1* Trial 2* Trial 1 Trial 1 Trial 1 Trial 2 (seconds) 2.8 3.0 115.8a 117.3a 2.6 2.4 80.3 81.0 20 2.7 2.7 117.2a 99.7ab 2.4 2.4 77.7 94.0 40 2.9 2.5 80.2b 88.8b 2.2 2.6 76.6 88.0 60 2.5 2.0 76.6b 83.3b 2.7 2.6 107.2 94.2 80 *Means in columns followed by different letters are significantly different (P =s 0.05).
ACKNOWLEDGEMENTS The assistance of Cheryl Korman, Celeste Maiorana, and Andrea Reding in the collection, preparation and analysis of the samples is greatly appreciated. REFERENCES Card, L. E., and M. C. Nesheim, 1966. Poultry Production, Lee and Febiger, Philadelphia, Penn. Heath, J. L., and O. P. Thomas, 1973. The xanthophyll content and color of broiler skin after scalding. Poultry Sci. 52: 967-971. Klose, A. A., E. P. Mecchi and M. F. Pool, 1961. Observations on factors influencing feather release. Poultry Sci. 40: 1029-1036. Mountney, G. J., 1966. Poultry Products Technology. The Avi Publishing Co., Inc., Westport, Conn. Parnell.E.D.,O.D.Butler andS.Cover, 1950. Storage tests with unwrapped frozen fryers. Texas Agric. Exp. Sta. Progress Rept. 1270. Pearce, J. A., and C. G. Lavers, 1949. Frozen storage of poultry. V. Effects of some processing factors on quality. Canadian J. Research, 27: 253-265. Pool, M. F., E. P. Mecchi, H. Lineweaver and A. A. Klose, 1954. The effect of scalding temperature on the processing and initial appearance of turkeys. Poultry Sci., 33: 274-279. Steel, R. F. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Book Company, Inc., New York.
AUGUST 19-23, 1974. THE IV INTERNATIONAL SYMPOSIUM ON RUMINANT PHYSIOLOGY, SYDNEY, AUSTRALIA.
SEPTEMBER 22-27, 1974. IV INTERNATIONAL CONGRESS OF FOOD SCIENCE AND TECHNOLOGY, MADRID, SPAIN.
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the lipid underlying the feather tract becoming more soft and facilitating removal and/or dispersion of the xanthophyll containing lipid. This experiment demonstrated that the pick time did have an effect on the xanthophyll content of the broiler carcass and this effect was influenced by the scalding conditions of the experiment. The two scald times were selected to fall between those of experiment 2 and those mentioned as previous work in experiment 2 in an attempt to determine the effect of scald time on xanthophyll content. A significant (P =£ 0.05) increase in the xanthophylll content of the breast skin was found as the scald time was increased from 60 to 90 seconds. This could be due to the feathers being loosened to a greater degree at 90 seconds of scald than at 60 seconds resulting in less skin damage. No significant differences were found when the xanthophyll content of the feather tract was examined. This research indicated that scald times less than 90 seconds had an influence on xanthophyll content of the skin but when increased above 90 seconds there were no significant differences found attributable to scald time.