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Research Note: Effects of Wing Restraints on the Objective Texture of Commercially Processed Broiler Breast Meat
RESEARCH NOTES Research Note: Effects of Wing Restraints on the Objective Texture of Commercially Processed Broiler Breast Meat C. E. LYON, 1 M. C. ROBACH, 2 C. M. PAPA, 3 and R L. WILSON, J R 4 Poultry Processing and Meat Quality Research Unit, USDA, Agriculture Research Service, Russell Research Center, Athens, Georgia, 30613
1992 Poultry Science 71:1228-1231
INTRODUCTION The increased demand for deboned broiler breast meat has resulted in a desire by processors to shorten the post-mortem time prior to removal of the Pectoralis major (P. major) muscles from the carcass. The traditional aging period of 6 to 24 h post-mortem necessary to ensure tender-
Received for publication November 22, 1991. Accepted for publication March 16, 1992. Poultry Processing and Meat Quality Research Unit. ^Zontinental Grain Co., Wayne Farms Division, Duluth, GA 30136. 3 OK Foods Inc., Fort Smith, AR 72902. Biometrics Unit, USDA, Agricultural Research Service, South Atlantic Area, Russell Research Center, Athens, GA 30613.
ness (Lyon et al., 1985; Dawson et al., 1987) does not lend itself to an abbreviated postmortem time. Researchers have evaluated various treatments to achieve ultimate textural characteristics without the traditional post-mortem aging period. Some of these treatments have included electrical stimulation of the carcass during the initial stages of processing (Thompson et ah, 1987; Froning and Uijttenboogaart, 1988; Lyon et al, 1989; Sams et al, 1989), and high temperature conditioning of the carcass (Papa and Fletcher, 1988a). In contrast to these electrical and environmental temperature treatments, Papa et al. (1989) reported that a physical treatment, termed wing restraint (WR), tensioned the breast muscles by fixing the wings behind the back of the carcass. This
1228
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ABSTRACT A physical treatment was applied to broiler carcasses during commercial processing to evaluate its effectiveness in shortening the postmortem time necessary to achieve tenderness in cooked Pectoralis major (P. major) meat. Pectoralis major muscles were stretched by using cable ties to position the wings behind the back of the carcass. The restraints were removed from the carcasses at two postchill times: within 15 min (WR) and after 1 h (WR + 1). Treated carcasses were compared with a control group of carcasses. Pectoralis major muscles were removed from control carcasses and WR carcasses between 10 and 15 min postchill. Muscles were held at 2 C until the next day, when they were cooked. Two 1.9-cm-wide strips, noted as anterior and medial, were removed from each sample and objective texture determined. The experiment was replicated five times with a total of 82, 80, and 79 carcasses evaluated for the control, WR, and WR + 1 groups, respectively. There were significant differences in objective texture due to the physical treatment and location in the muscle. The lowest shear value (5.5 kg) was noted for the WR + 1 group at the anterior location. Significantly lower shear values were noted for the anterior strip compared with the medial strip. Physically restraining the P. major muscles during processing and holding for 1 h postchill resulted in a significant reduction in force to shear broiler breast meat. (Key words: broiler breast meat, wing restraints, muscle tension, postchill deboning, texture)
RESEARCH NOTE
treatment lengthened the sarcomeres and resulted in lower shear values for muscles removed from the carcass 2 h postmortem compared with a control group. The Papa et at (1989) study was conducted on a pilot plant basis. The purpose of the present experiment was to evaluate the effects of applying WR to broiler carcasses on the texture of the P. major meat deboned at two postchill times. All processing was done under commercial conditions.
MATERIALS AND METHODS
Mixed sex carcasses were randomly selected at the transfer point between the picking and evisceration lines of a commercial broiler processing plant. The carcasses were hung by the hocks on an off-line shackle stand while WR were applied. The WR procedure has been previously reported by Papa et al. (1989). For each of five replications, WR were placed on 40 carcasses. The time from hanging the carcasses on the line prior to evisceration to entering the prechiller was approximately 15 min. Carcasses were in the single-unit, augertype prechiller-chiller for approximately 40 min. When all of the carcasses with WR were in the prechiller, an unrestrained control group of carcasses was collected from the exit end of the chiller. Both P. major muscles were removed from these carcasses within 15 min. When the WR carcasses exited the chiller, they were separated into two equal groups: WR and WR + 1. The WR denotes that both the WR and the P. major muscles were removed within 15 min postchill. Under controlled conditions, the carcasses would have been subjected to the WR for 80 min. This would have included 10 min to apply WR, 15 min on the evisceration line, 40 min in the prechiller-chiller, and 15 min to remove the WR. Actual times ranged from 75 to 85 min. The WR + 1 denotes that the carcasses were held with the WR intact for 1
5
Instron Corp., Canton, MA 02021.
h postchill prior to removal of the P. major muscles. The carcasses were covered with ice during this holding time. The WR + 1 carcasses should have been subjected to the WR for 140 min. Actual times ranged from 135 to 145 min. A pair of scissors was used to cut the WR prior to muscle removal. Each carcass was placed on a stationary cone and the P. major muscles removed with a knife by partially cutting through the joint cavity of the humerus and along the clavicle while pulling down toward the posterior end of the breast. The same person removed all of the muscles. The P. major muscles from each carcass were placed in labeled plastic bags, covered with ice, and transported to the laboratory.
Cooking The muscles from the control, WR, and WR + 1 groups were held at 2 C for approximately 20 h. Each muscle was then removed from its original bag, examined for tissue damage, placed in a heat-and-seal bag, and cooked in 85 C water for 30 min. Although specific end-point temperatures were not noted, heating breasts in heat-andseal bags under these conditions in previous experiments resulted in end-point temperatures of 80 C. After cooling in tap water for 15 min, the bags were opened and the intact meat was removed.
Objective Texture Texture measurements were made on two 1.9-cm-wide strips from each intact meat sample. Orientation of the strips was from the humeral insertion to the keel, and the second strip was directly posterior to the initial strip. The height of each strip at the point of shearing was measured. The strips, designated as anterior (Strip 1) and medial (Strip 2), were sheared with a Warner-Bratzler attachment to the Instron Model 1122.5 Cross head speed was 200 m m per min. Shearing force was perpendicular to the direction of the fibers. The peak load was recorded in kilograms. Height of each strip at the point of shearing was also recorded so that force to shear could be expressed according to the sample dimensions. Texture data were
Downloaded from http://ps.oxfordjournals.org/ by guest on April 21, 2015
Application and Removal of Wing Restraints
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LYON ET AL.
TABLE 1. Effects of applying wing restraints to broiler carcasses during processing on height and objective texture of the cooked Pectoralis major meat
treatment Wings not restrained (control) Wings restrained until after chilling (WR) Wings restrained for 1 h after chilling (WR + 1)
Height of the meat2
Warner-Bratzler shear values Anterior 2
Medial 2
(cm) 2.36 ± .29*
(kg/cm ) (kg) 2.6 ± \2* 11.8 ± 3.9*
(kg/cm ) (kg) 3.2 ± 1.3a 14.1 ± 6.1a
2.27 ± .28a
2.1 ± .9b 9.2 ± 4.4a
2.9 ± 1.3a 12.4 ± 4.2a
2.17 ± .24b
1.3 ± .7° S3 ± 3.4b
1.7 ± .7* 7.2 ± 3.6b
a_c
Means ± SD within columns with no common superscripts are significantly different (P < .05). AU carcasses were processed under commercial conditions. Wing restraints (WR) were applied at the transfer point; after removal of the feet, but prior to evisceration. The carcasses were subjected to the WR for approximately 80 min and the WR + 1 treatment for approximately 140 min. 2 Height of the meat was measured at the point used for shear analysis. Each value represents 328,320, and 316 observations for the control, WR, and WR + 1 group, respectively. ^Varner-Bratzler shear values were noted on two 1.9-cm wide strips from the anterior and medial regions of each Pectoralis major. The height of each strip at the point of shearing was measured so that sample dimensions could be included in the value. The shear value was also noted as kilograms so the values could be compared to sensory-objective values established earlier (Lyon and Lyon, 1991). Each shear value represents 164, 160, and 158 observations for the control, WR, and WR + 1 group, respectively. 1
Statistical Analysis The procedure as outlined was replicated five times. Each trip to the processing plant constituted a replication. The number of carcasses per treatment varied from 13 to 19 per replication because several carcasses were condemned by the USDA inspectors on the line, some were discarded after chilling due to bruises or cuts on the breast, and others were discarded at the lab due to damage in the area used for shear evaluation. If the left or right muscle was discarded due to a cut or tear in the breast, the other muscle from the same carcass was also discarded. Total number of carcasses per treatment for the five replications was 82 for the control group, 80 for the WR group, and 79 for the WR + 1 group. Data were subjected to ANOVA using the General Linear Models procedure of the base SAS® software (SAS Institute, 1987). The model included main effects of treatment, replication, location in the muscle, and their interactions. For the replication
and treatment main effects, the error term was the replication by treatment interaction term. For location effects, the error term was the pooled replication by location and replication by treatment by location interaction terms. Tukey's studentized range test was used to test for difference among means. Significance was accepted at the .05 level.
RESULTS AND DISCUSSION One of the concerns about the use of WR in a commercial plant was the possibility of altering the presentation of the internal organs to the eviscerators, subsequent rupture of the intestinal tract, and condemnation of the carcass. Based on visual observations, WR did not cause a problem with the automatic evisceration procedure. Cuts and tears during processing were the major causes of differences in the number of carcasses for the treatments. There was no difference in the height at the point of shearing between the anterior and medial strips within the treatments, so the data for locations were pooled (n = 328, 320, and 316 for the control, WR, and WR + 1 groups, respectively). Strips from the WR + 1 carcasses were significantly thinner than the strips from the control
Downloaded from http://ps.oxfordjournals.org/ by guest on April 21, 2015
averaged for each meat sample [(Strip 1 + Strip 2) + 2]. To determine whether there were treatment effects due to location, differences between the anterior and medial strips were also analyzed (Strip 1 versus Strip 2).
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RESEARCH NOTE
There were significant differences in shear values noted as kilograms of force due to both treatment and location (Table 1). The WR + 1 treatment resulted in significantly lower shear values than the other two groups, which were not significantly different from each other. The decrease from 9.2 kg for the anterior strip and 12.4 kg for the medial strip of the WR treatment to 5.5 and 7.2 kg for the anterior and medial strips of the WR + 1 treatment would not only be statistically significant but also be detectable based on the relationship of Warner-Bratzler shear values and the sensory perception of tenderness of broiler breast meat, as reported by Lyon and Lyon (1991). Shear values of 7.2 and 5.5 kg would be rated "slightly tender" on that sensory tenderness scale. The 9.2-kg shear value for the WR anterior strip would be rated as "slightly tough", and the other shear values would all be in the "moderately" to "very tough" portion of the sensory scale according to Lyon and Lyon (1991). Shear force values from the anterior strip were consistently lower than those from the medial strip for all of the treatments. This difference may be due to
the architecture of the P. major muscle. Papa and Fletcher (1988b) reported that the anterior portion of the broiler P. major reached the onset of rigor sooner and exhibited a greater extent of shortening compared with the posterior portions of the main belly of the muscle. The effect of tensioning due to the WR treatment applied in the present study appeared to be most pronounced in the anterior area of the P. major.
REFERENCES Dawson, P. L., D. M. Janky, M. G. Dukes, L. D. Thompson, and S. A. Woodward, 1987. Effect of post-mortem boning time during simulated commercial processing on the tenderness of broiler breast meat. Poultry Sci. 66:1331-1333. Froning, G. W., and T. G. Uijttenboogaart, 1988. Effect of post-mortem electrical stimulation on color, texture, pH, and cooking losses of hot and cold deboned chicken broiler breast meat. Poultry Sci. 67:1536-1544. Lyon, B. G., and C. E. Lyon, 1991. Research Note: Shear value ranges by Instron Warner-Bratzler and single-blade Allo-Kramer devices that correspond to sensory tenderness. Poultry Sci. 70: 188-191. Lyon, C. E., C. E. Davis, J. A. Dickens, C. M. Papa, and J. O. Reagan, 1989. Effects of electrical stimulation on the post-mortem biochemical changes and texture of broiler Pectoralis muscle. Poultry Sci. 68:249-257. Lyon, C. E., D. Hamm, and J. E. Thomson, 1985. pH and tenderness of broiler breast meat deboned various times after chilling. Poultry Sci. 64: 307-310. Papa, C. M., and D. L. Fletcher, 1988a. Effect of aging temperature on broiler breast meat. Poultry Sci. 67:1147-1153. Papa, C. M., and D. L. Fletcher, 1988b. Effect of wing restraints on postmortem muscle shortening and the textural quality of broiler breast meat. Poultry Sci. 67275-279. Papa, C. M., C. E. Lyon, and D. L. Fletcher, 1989. Effects of post-mortem wing restraint on the development of rigor and tenderness of broiler breast meat. Poultry Sci. 68:238-243. Sams, A. R., D. M. Janky, and S. A. Woodward, 1989. Tenderness and R-Value changes in early harvested broiler breast tissue following postmortem electrical stimulation. Poultry Sci. 68: 1232-1235. SAS Institute, 1987. SAS/STAT® Guide for Personal Computers. Version 6 Edition. SAS Institute Inc., Cary, NC. Thompson, L. D., D. M. Janky, and S. A. Woodward, 1987. Tenderness and physical characteristics of broiler breast fillets harvested at various times from postmortem electrically stimulated carcasses. Poultry Sci. 66:1158-1167.
Downloaded from http://ps.oxfordjournals.org/ by guest on April 21, 2015
and WR carcasses (Table 1). This difference in height indicates that the WR + 1 treatment was inhibiting shortening of the fibers in this region of the P. major muscles. Significant differences in shear values expressed as kilograms per square centimeter were noted (Table 1). For the anterior location, there were significant differences due to treatment, with the WR + 1 treatment resulting in the lowest shear values, 1.3 kg/cm 2 , and the control group the highest shear values, 2.6 kg/cm 2 . For the medial location, shear values for the WR + 1 treatment were significantly lower than shear values for the control and WR treatments. There were also significant differences in force to shear due to location. For the control carcasses, the medial location required significantly more force to shear than the anterior location; 3.2 k g / c m 2 to 2.6 kg/cm 2 , respectively. This difference may reflect differences in the rate of rigor development, as reported by Papa and Fletcher (1988b).
1992 Poultry Science 71:1228-1231
INTRODUCTION The increased demand for deboned broiler breast meat has resulted in a desire by processors to shorten the post-mortem time prior to removal of the Pectoralis major (P. major) muscles from the carcass. The traditional aging period of 6 to 24 h post-mortem necessary to ensure tender-
Received for publication November 22, 1991. Accepted for publication March 16, 1992. Poultry Processing and Meat Quality Research Unit. ^Zontinental Grain Co., Wayne Farms Division, Duluth, GA 30136. 3 OK Foods Inc., Fort Smith, AR 72902. Biometrics Unit, USDA, Agricultural Research Service, South Atlantic Area, Russell Research Center, Athens, GA 30613.
ness (Lyon et al., 1985; Dawson et al., 1987) does not lend itself to an abbreviated postmortem time. Researchers have evaluated various treatments to achieve ultimate textural characteristics without the traditional post-mortem aging period. Some of these treatments have included electrical stimulation of the carcass during the initial stages of processing (Thompson et ah, 1987; Froning and Uijttenboogaart, 1988; Lyon et al, 1989; Sams et al, 1989), and high temperature conditioning of the carcass (Papa and Fletcher, 1988a). In contrast to these electrical and environmental temperature treatments, Papa et al. (1989) reported that a physical treatment, termed wing restraint (WR), tensioned the breast muscles by fixing the wings behind the back of the carcass. This
1228
Downloaded from http://ps.oxfordjournals.org/ by guest on April 21, 2015
ABSTRACT A physical treatment was applied to broiler carcasses during commercial processing to evaluate its effectiveness in shortening the postmortem time necessary to achieve tenderness in cooked Pectoralis major (P. major) meat. Pectoralis major muscles were stretched by using cable ties to position the wings behind the back of the carcass. The restraints were removed from the carcasses at two postchill times: within 15 min (WR) and after 1 h (WR + 1). Treated carcasses were compared with a control group of carcasses. Pectoralis major muscles were removed from control carcasses and WR carcasses between 10 and 15 min postchill. Muscles were held at 2 C until the next day, when they were cooked. Two 1.9-cm-wide strips, noted as anterior and medial, were removed from each sample and objective texture determined. The experiment was replicated five times with a total of 82, 80, and 79 carcasses evaluated for the control, WR, and WR + 1 groups, respectively. There were significant differences in objective texture due to the physical treatment and location in the muscle. The lowest shear value (5.5 kg) was noted for the WR + 1 group at the anterior location. Significantly lower shear values were noted for the anterior strip compared with the medial strip. Physically restraining the P. major muscles during processing and holding for 1 h postchill resulted in a significant reduction in force to shear broiler breast meat. (Key words: broiler breast meat, wing restraints, muscle tension, postchill deboning, texture)
RESEARCH NOTE
treatment lengthened the sarcomeres and resulted in lower shear values for muscles removed from the carcass 2 h postmortem compared with a control group. The Papa et at (1989) study was conducted on a pilot plant basis. The purpose of the present experiment was to evaluate the effects of applying WR to broiler carcasses on the texture of the P. major meat deboned at two postchill times. All processing was done under commercial conditions.
MATERIALS AND METHODS
Mixed sex carcasses were randomly selected at the transfer point between the picking and evisceration lines of a commercial broiler processing plant. The carcasses were hung by the hocks on an off-line shackle stand while WR were applied. The WR procedure has been previously reported by Papa et al. (1989). For each of five replications, WR were placed on 40 carcasses. The time from hanging the carcasses on the line prior to evisceration to entering the prechiller was approximately 15 min. Carcasses were in the single-unit, augertype prechiller-chiller for approximately 40 min. When all of the carcasses with WR were in the prechiller, an unrestrained control group of carcasses was collected from the exit end of the chiller. Both P. major muscles were removed from these carcasses within 15 min. When the WR carcasses exited the chiller, they were separated into two equal groups: WR and WR + 1. The WR denotes that both the WR and the P. major muscles were removed within 15 min postchill. Under controlled conditions, the carcasses would have been subjected to the WR for 80 min. This would have included 10 min to apply WR, 15 min on the evisceration line, 40 min in the prechiller-chiller, and 15 min to remove the WR. Actual times ranged from 75 to 85 min. The WR + 1 denotes that the carcasses were held with the WR intact for 1
5
Instron Corp., Canton, MA 02021.
h postchill prior to removal of the P. major muscles. The carcasses were covered with ice during this holding time. The WR + 1 carcasses should have been subjected to the WR for 140 min. Actual times ranged from 135 to 145 min. A pair of scissors was used to cut the WR prior to muscle removal. Each carcass was placed on a stationary cone and the P. major muscles removed with a knife by partially cutting through the joint cavity of the humerus and along the clavicle while pulling down toward the posterior end of the breast. The same person removed all of the muscles. The P. major muscles from each carcass were placed in labeled plastic bags, covered with ice, and transported to the laboratory.
Cooking The muscles from the control, WR, and WR + 1 groups were held at 2 C for approximately 20 h. Each muscle was then removed from its original bag, examined for tissue damage, placed in a heat-and-seal bag, and cooked in 85 C water for 30 min. Although specific end-point temperatures were not noted, heating breasts in heat-andseal bags under these conditions in previous experiments resulted in end-point temperatures of 80 C. After cooling in tap water for 15 min, the bags were opened and the intact meat was removed.
Objective Texture Texture measurements were made on two 1.9-cm-wide strips from each intact meat sample. Orientation of the strips was from the humeral insertion to the keel, and the second strip was directly posterior to the initial strip. The height of each strip at the point of shearing was measured. The strips, designated as anterior (Strip 1) and medial (Strip 2), were sheared with a Warner-Bratzler attachment to the Instron Model 1122.5 Cross head speed was 200 m m per min. Shearing force was perpendicular to the direction of the fibers. The peak load was recorded in kilograms. Height of each strip at the point of shearing was also recorded so that force to shear could be expressed according to the sample dimensions. Texture data were
Downloaded from http://ps.oxfordjournals.org/ by guest on April 21, 2015
Application and Removal of Wing Restraints
1229
1230
LYON ET AL.
TABLE 1. Effects of applying wing restraints to broiler carcasses during processing on height and objective texture of the cooked Pectoralis major meat
treatment Wings not restrained (control) Wings restrained until after chilling (WR) Wings restrained for 1 h after chilling (WR + 1)
Height of the meat2
Warner-Bratzler shear values Anterior 2
Medial 2
(cm) 2.36 ± .29*
(kg/cm ) (kg) 2.6 ± \2* 11.8 ± 3.9*
(kg/cm ) (kg) 3.2 ± 1.3a 14.1 ± 6.1a
2.27 ± .28a
2.1 ± .9b 9.2 ± 4.4a
2.9 ± 1.3a 12.4 ± 4.2a
2.17 ± .24b
1.3 ± .7° S3 ± 3.4b
1.7 ± .7* 7.2 ± 3.6b
a_c
Means ± SD within columns with no common superscripts are significantly different (P < .05). AU carcasses were processed under commercial conditions. Wing restraints (WR) were applied at the transfer point; after removal of the feet, but prior to evisceration. The carcasses were subjected to the WR for approximately 80 min and the WR + 1 treatment for approximately 140 min. 2 Height of the meat was measured at the point used for shear analysis. Each value represents 328,320, and 316 observations for the control, WR, and WR + 1 group, respectively. ^Varner-Bratzler shear values were noted on two 1.9-cm wide strips from the anterior and medial regions of each Pectoralis major. The height of each strip at the point of shearing was measured so that sample dimensions could be included in the value. The shear value was also noted as kilograms so the values could be compared to sensory-objective values established earlier (Lyon and Lyon, 1991). Each shear value represents 164, 160, and 158 observations for the control, WR, and WR + 1 group, respectively. 1
Statistical Analysis The procedure as outlined was replicated five times. Each trip to the processing plant constituted a replication. The number of carcasses per treatment varied from 13 to 19 per replication because several carcasses were condemned by the USDA inspectors on the line, some were discarded after chilling due to bruises or cuts on the breast, and others were discarded at the lab due to damage in the area used for shear evaluation. If the left or right muscle was discarded due to a cut or tear in the breast, the other muscle from the same carcass was also discarded. Total number of carcasses per treatment for the five replications was 82 for the control group, 80 for the WR group, and 79 for the WR + 1 group. Data were subjected to ANOVA using the General Linear Models procedure of the base SAS® software (SAS Institute, 1987). The model included main effects of treatment, replication, location in the muscle, and their interactions. For the replication
and treatment main effects, the error term was the replication by treatment interaction term. For location effects, the error term was the pooled replication by location and replication by treatment by location interaction terms. Tukey's studentized range test was used to test for difference among means. Significance was accepted at the .05 level.
RESULTS AND DISCUSSION One of the concerns about the use of WR in a commercial plant was the possibility of altering the presentation of the internal organs to the eviscerators, subsequent rupture of the intestinal tract, and condemnation of the carcass. Based on visual observations, WR did not cause a problem with the automatic evisceration procedure. Cuts and tears during processing were the major causes of differences in the number of carcasses for the treatments. There was no difference in the height at the point of shearing between the anterior and medial strips within the treatments, so the data for locations were pooled (n = 328, 320, and 316 for the control, WR, and WR + 1 groups, respectively). Strips from the WR + 1 carcasses were significantly thinner than the strips from the control
Downloaded from http://ps.oxfordjournals.org/ by guest on April 21, 2015
averaged for each meat sample [(Strip 1 + Strip 2) + 2]. To determine whether there were treatment effects due to location, differences between the anterior and medial strips were also analyzed (Strip 1 versus Strip 2).
1231
RESEARCH NOTE
There were significant differences in shear values noted as kilograms of force due to both treatment and location (Table 1). The WR + 1 treatment resulted in significantly lower shear values than the other two groups, which were not significantly different from each other. The decrease from 9.2 kg for the anterior strip and 12.4 kg for the medial strip of the WR treatment to 5.5 and 7.2 kg for the anterior and medial strips of the WR + 1 treatment would not only be statistically significant but also be detectable based on the relationship of Warner-Bratzler shear values and the sensory perception of tenderness of broiler breast meat, as reported by Lyon and Lyon (1991). Shear values of 7.2 and 5.5 kg would be rated "slightly tender" on that sensory tenderness scale. The 9.2-kg shear value for the WR anterior strip would be rated as "slightly tough", and the other shear values would all be in the "moderately" to "very tough" portion of the sensory scale according to Lyon and Lyon (1991). Shear force values from the anterior strip were consistently lower than those from the medial strip for all of the treatments. This difference may be due to
the architecture of the P. major muscle. Papa and Fletcher (1988b) reported that the anterior portion of the broiler P. major reached the onset of rigor sooner and exhibited a greater extent of shortening compared with the posterior portions of the main belly of the muscle. The effect of tensioning due to the WR treatment applied in the present study appeared to be most pronounced in the anterior area of the P. major.
REFERENCES Dawson, P. L., D. M. Janky, M. G. Dukes, L. D. Thompson, and S. A. Woodward, 1987. Effect of post-mortem boning time during simulated commercial processing on the tenderness of broiler breast meat. Poultry Sci. 66:1331-1333. Froning, G. W., and T. G. Uijttenboogaart, 1988. Effect of post-mortem electrical stimulation on color, texture, pH, and cooking losses of hot and cold deboned chicken broiler breast meat. Poultry Sci. 67:1536-1544. Lyon, B. G., and C. E. Lyon, 1991. Research Note: Shear value ranges by Instron Warner-Bratzler and single-blade Allo-Kramer devices that correspond to sensory tenderness. Poultry Sci. 70: 188-191. Lyon, C. E., C. E. Davis, J. A. Dickens, C. M. Papa, and J. O. Reagan, 1989. Effects of electrical stimulation on the post-mortem biochemical changes and texture of broiler Pectoralis muscle. Poultry Sci. 68:249-257. Lyon, C. E., D. Hamm, and J. E. Thomson, 1985. pH and tenderness of broiler breast meat deboned various times after chilling. Poultry Sci. 64: 307-310. Papa, C. M., and D. L. Fletcher, 1988a. Effect of aging temperature on broiler breast meat. Poultry Sci. 67:1147-1153. Papa, C. M., and D. L. Fletcher, 1988b. Effect of wing restraints on postmortem muscle shortening and the textural quality of broiler breast meat. Poultry Sci. 67275-279. Papa, C. M., C. E. Lyon, and D. L. Fletcher, 1989. Effects of post-mortem wing restraint on the development of rigor and tenderness of broiler breast meat. Poultry Sci. 68:238-243. Sams, A. R., D. M. Janky, and S. A. Woodward, 1989. Tenderness and R-Value changes in early harvested broiler breast tissue following postmortem electrical stimulation. Poultry Sci. 68: 1232-1235. SAS Institute, 1987. SAS/STAT® Guide for Personal Computers. Version 6 Edition. SAS Institute Inc., Cary, NC. Thompson, L. D., D. M. Janky, and S. A. Woodward, 1987. Tenderness and physical characteristics of broiler breast fillets harvested at various times from postmortem electrically stimulated carcasses. Poultry Sci. 66:1158-1167.
Downloaded from http://ps.oxfordjournals.org/ by guest on April 21, 2015
and WR carcasses (Table 1). This difference in height indicates that the WR + 1 treatment was inhibiting shortening of the fibers in this region of the P. major muscles. Significant differences in shear values expressed as kilograms per square centimeter were noted (Table 1). For the anterior location, there were significant differences due to treatment, with the WR + 1 treatment resulting in the lowest shear values, 1.3 kg/cm 2 , and the control group the highest shear values, 2.6 kg/cm 2 . For the medial location, shear values for the WR + 1 treatment were significantly lower than shear values for the control and WR treatments. There were also significant differences in force to shear due to location. For the control carcasses, the medial location required significantly more force to shear than the anterior location; 3.2 k g / c m 2 to 2.6 kg/cm 2 , respectively. This difference may reflect differences in the rate of rigor development, as reported by Papa and Fletcher (1988b).