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Studies on Tenderness Evaluation1
Studies on Tenderness Evaluation1 J. W. DODGE2 AND W. J. STADELMAN Purdue University, Lafayette,
Ind.
(Received for publication June 10, 1959)
1
Journal paper No. 1443 of the Purdue Agricultural Experiment Station. 2 Present address: Nichols, Inc., Exeter, N.H.
.86 between tenderness measurement by the Kramer shear press an a taste panel. Wise (1957) reported a .89 correlation between a chew panel and the Kramer shear press. Cameron and Ryan (1955) reported that sample size had had a great influence on tenderness measurement with the Kramer shear press, but of the known methods of objective measurement this machine proved to be the most satisfactory on poultry meat. Dodge and Stadelman (1959) reported dehydration of cooked samples had considerable influence in tenderness readings on the Kramer shear press. The machine which has been found to work most satisfactorily in this laboratory is the Kramer shear press. This device works on the principle of shearing force, from which action the pounds of force required to shear a gram of meat can be calculated. Several problems have arisen in the use of this machine in this laboratory— such as the variation caused by sample size and thickness, moisture, amount of connective tissue in the sample, and dehydration during sampling. These problems have been solved by adjustments in technique so that within any one given experiment the tenderness evaluation can be kept very uniform. The greatest problem in tenderness evaluation—whether by panel or machine—is that the samples have always had to be cooked. Nothing in the literature reviewed suggests any degree of success obtained by testing raw poultry meat. If meat could be tested raw, it would eliminate the time, cost and possible source of variation in-
184
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 10, 2015
'"TpENDERNESS measurement is a rela-*- tive evaluation of one of the most important quality factors in meat. Two methods are commonly employed. The first is the organoleptic panel where each member is given a sample to evaluate—either by the number of chews required to masticate the meat or by ranking judgment on some sort of decanoic scale. With even a small panel of conscientious members a good relative evaluation can be obtained. This is considered to be the most accurate evaluation of tenderness. Tenderness is also measured by machine. Several mechanical devices are available for just such a purpose. However, none of these machines appear to be able to simulate the true action of a chewing mouth, and consequently each approximates that action with only a certain degree of success. Of the mechanical devices used the Warner Bratzler shear machine has been most widely reported, but the best relationships between a mechanical device and a competent panel have been established with the Kramer shear press. Deatherage and Garnatz (1952) reported that a poor correlation existed between the Warner Bratzler shear machine and a competent panel when working with beef. Bochian, Anglemier and Sather (1958) found a good but negative correlation (r = .65) between a taste panel and a grinder method of tenderness measurement. Shannon, Marion and Stadelman (1957) reported a correlation of
TENDERNESS EVALUATION
curred during the cooking process. Consequently, the purpose of this study was to find out if good tenderness evaluation could be obtained by the shearing of raw meat, on the Kramer shear press. EXPERIMENTAL PROCEDURE
toralis major muscle was packaged in polyethylene and frozen at 0 degrees F. After thawing the meat for eight hours at room temperature (65 degrees F.) four uniform samples weighing two grams each were cut from each muscle for a panel evaluation. The panel consisted of four trained members and each member scored the sample by the number of chews necessary before swallowing—including the swallowing chew. Thus on each bird 12 evaluations were made, or a total of 300 evaluations for the complete experiment, including 100 raw shearing evaluations, 100 cooked shearing evaluations, and 100 panel evaluations. For statistical analysis the four scores from each method of evaluation within each bird were matched at random and correlated. The correlations were calculated for different aging periods to determine any existing relationships that might prove worthwhile to note. Experiment 2. Twelve, 24-week-old, Broad White turkeys were used in this experiment. The birds were slaughtered by the same method used in Experiment 1. Four birds each were aged in slush ice for periods of 2 hours, 6 hours, and 10 hours. Samples were obtained by the same method as in Experiment 1 with the exception that for every bird tested three samples were obtained for raw shearing, three for cooked shearing, and three for panel evaluation of each size—one gram, two grams, and three grams. Three panel members were employed. For analysis, averages were taken on each bird for each method of evaluation. These averages were analyzed by correlation. RESULTS AND DISCUSSION Experiment 1. The results of the analysis of this experiment may be seen on Table 1. From Table 1 it can be seen that in
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 10, 2015
Experiment 1. A sampling device was constructed from high grade tool steel. This sampler was designed to cut a sample of meat 6.6 cm. long (the width of the testing cell of the Kramer shear press), 2.0 cm. wide and 1 cm. thick. Samples of uniform size could thus be obtained for shearing. Because of the possibility of variation in density of the meat the samples were still weighed to the nearest tenth of a gram and the shear score was calculated on the basis of shearing force required per gram of meat. Twenty-five, 35-week-old, Broad Breasted Bronze turkeys were used in the experiment. All birds were slaughtered by conventional methods, eviscerated, and chilled in slush ice. Five birds each were aged for periods of 2 hours, 6 hours, 10 hours, 16 hours, and 24 hours. At the end of the given aging periods the carcasses were removed from the slush ice and drained. The wings and legs were removed from the carcass as was one side of the breast. Four shearing evaluations were made immediately on each raw pectoralis major muscle obtained. The remaining side of the breast was enveloped with a two-sheet covering of .0015 gauge aluminum foil and roasted for 2 hours at 330 degrees F. in a reel-type oven. The cooked meat was cooled for 20 minutes before four evaluations were made on the cooked muscle in the same relative positions as the raw samples were obtained. On both the raw and cooked shearing evaluations the samples were extracted from as close to the center of the muscle as possible. The remaining cooked meat from the pec-
185
186
J. W. DODGE AND W. J. STADELMAN TABLE 1.—Results of correlation analysis in experiment 1 r values obtained Raw vs. cooked
Raw vs. panel
Cooked Degrees of vs. panel freedom
2 6 10 16 24 2 and 6 6 and 10 2,6 and 10 2,6,10,16 2,6,10,16,24
.2256 .3702 .2966 -.4896 .1 .4875 .6150 .7184 .6431 .6530
.3883 .1881 .1 .1695 .1 .4451 .3854 .5619 .5609 .5247
.5237 .6904 .3766 - .2966 .1 .6521 .6600 .7075 .6620 .6538
For significance , at .01 level* at 18 degrees of freedom r value = at 38 degrees of freedom r value = at 58 degrees of freedom r value = at 78 degrees of freedom r value = at 98 degrees of freedom r value = For significance at .05 level at 18 degrees of freedom r value = at 38 degrees of freedom r value =
18 18 18 18 18 38 38 58 78 98
.561 .405 .331 .307 .257 .444 .316
* Snedecor 1957.
many cases the r values are high—showing a good relationship between methods of evaluation. However the highest r value obtained is on the relationship between the raw shear and cooked shear at the 2, 6, and 10 hour periods. This r value is .7184. The predictability (R or r2) is only .516 or slightly over 50 percent. These r values are much lower than those reported by Shannon et al. (1957) and Wise (1957). Several factors could contribute to this result. First, a fatigue of the panel members was noticed during the panel evaluation. Possibly the sample size was large enough to produce considerable difference between the first and last evaluation in the test. Second, the previous reports are with chicken meat. The structure of turkey meat appears more gross and coarse, so possibly this would affect the results. Third, the method of statistical analysis could be improved. The samples for shearing were cut from the center of the muscle and the sam-
Aging time (hours) 2, 6, and 10
2, 6,10,16, and 24
Relationships
Degree of free- P r value dom .01»
rawXcooked shear raw shear Xpanel cooked shearXpanel
.7928 .7254 .9297
13 13 13
.641
raw Xcooked shear raw shearXpanel cooked shearXpanel
.7232 .7254 .8375
23 23 23
.505
* Snedecor, 1957.
pies for panel evaluation were cut from the area immediately surrounding this. Although the difference should be very small some variation could exist. The number of chews on the same muscle varied with the individual panel members. Therefore, it seemed wise to average the scores for the treatments and re-analyze the results. The results of this analysis may be seen on Table 2. The resulting r values as shown on Table 2 are much higher by this method of calculation. Several conclusions can be drawn from these results. First, although the relationship between raw shearing and chew panel appear high, the relationship between the cooked shear and the chew panel are even higher. This means that until some other method is devised for raw meat evaluation it is still not as good for research purposes as the cooked shear evaluation. Second, it may be noticed that at the longer aging periods the relationship is rather poor. One could conclude from this that as very small differences in tenderness arise the shear machine is not a good indication of the panel evaluation. It would consequently appear that for the time being if consumer acceptability of cooked meat is to be estimated, then the evaluation should be made on cooked meat. Again the question arises as to what effect cooking has on tenderization. The matter of sample
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 10, 2015
Aging period testedhours
TABLE 2.—Results of correlation between raw shear, cooked shear, and panel evaluation averages for each bird at selected aging times in experiment 1
187
TENDERNESS EVALUATION TABLE 3.—Relationships between raw and cooked shear measurements and panel evaluations on three sample sizes of cooked turkey meat —All relationships being shown for aging periods of 2 hours, 6 hours, and 10 hours DcETCCS
Treatments
r values
Raw shear vs. cooked shear Raw shear vs. 1-gram chew Raw shear vs. 2-gram chew Raw shear vs. 3-gram chew Cooked shear vs. 1-gram chew Cooked shear vs. 2-gram chew Cooked shear vs. 3-gram chew
.8724 .6933 .7582 . 6992 . 8041 .7461 .8050
of P .01 P .05* freedom 10 10 10 10 10 10 10
.708 .708 .708 .708 .708 .708 .708
.576 .576 .576 .576 .576 .576 .576
size had still not been investigated, so another experiment was designed to look into this. Experiment 2. The results of Experiment 2 are shown in Table 3. An interesting point arises from the results as shown in Table 3. On the raw shearing the highest correlation was with the two-gram chew, while on the cooked shearing this particular relationship provided the lowest correlation. The reasoning behind this is hard to explain, unless it is because of the limited number of samples employed. Nevertheless in each case there is close proximity between the shearing and one-gram chew and three-gram chew evaluation relationships. On these particular sized samples the correlation between shearing and chewing is much higher for the cooked samples. Thus a small difference is noticeable between sample size with no particular trend involved. SUMMARY
In this study 37 turkeys were used to study tenderness evaluation by shearing both raw and cooked samples on the Kramer shear press. The shear scores were
REFERENCES Bockian, A. H., A. F. Englemier and L. A. Sather, 19S8. A comparison of and objective subjective measurement of beef tenderness. Food Technol. 12: 483-485. Cameron, J. K., and E. A. Ryan, 19SS. Tenderness in poultry meat I. An improved method of measuring. Food Technol. 9: 29. Deatherage, F. E., and G. Garnatz, 19S2. A comparative study of tenderness by sensory panel and by shear strength measurements. Food Technol. 6: 260-262. Dodge, J. W., and W. J. Stadelman, 1959. Postmortem aging of poultry meat and its effect on the tenderness of the breast muscles. Food Technol. 13: 81-84. Shannon, W. G., W. W. Marion and W. J. Stadelman, 1957. Effect of temperature and time of scalding on the tenderness of the breast meat of chicken. Food Technol. 11: 284-286. Snedecor, G. W., 1957. Statistical Methods, Fifth Edition, Iowa State College Press, Ames, Iowa. Wise, R. G., 1957. Effect of beating by mechanical pickers on the tenderness of poultry meat. A thesis, M.S., Purdue University. Lafayette, Indiana.
March 31, April 1-2. Pacific Dairy and Poultry Association Annual Convention, Las Vegas, Nevada. April 11-13. Poultry and Egg National Board, Annual Meeting, La Salle Hotel, Chicago, Illinois.
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 10, 2015
* Snedecor, 1957.
compared to evaluations made by a competent chew panel. In the first experiment four samples were sheared raw, four were sheared cooked, and four cooked samples were evaluated by the panel on each bird. The results indicated that although significant correlations were produced between raw shearing and the panel evaluation of the cooked samples on the same carcass, the relationship was not as high as that found between cooked sample shearing and the panel evaluations. In the second experiment it was found that the size of sample offered to the panel may influence the relationships found in such a study but no particular trend in respect to the effect of size on the relationship was evident.
Ind.
(Received for publication June 10, 1959)
1
Journal paper No. 1443 of the Purdue Agricultural Experiment Station. 2 Present address: Nichols, Inc., Exeter, N.H.
.86 between tenderness measurement by the Kramer shear press an a taste panel. Wise (1957) reported a .89 correlation between a chew panel and the Kramer shear press. Cameron and Ryan (1955) reported that sample size had had a great influence on tenderness measurement with the Kramer shear press, but of the known methods of objective measurement this machine proved to be the most satisfactory on poultry meat. Dodge and Stadelman (1959) reported dehydration of cooked samples had considerable influence in tenderness readings on the Kramer shear press. The machine which has been found to work most satisfactorily in this laboratory is the Kramer shear press. This device works on the principle of shearing force, from which action the pounds of force required to shear a gram of meat can be calculated. Several problems have arisen in the use of this machine in this laboratory— such as the variation caused by sample size and thickness, moisture, amount of connective tissue in the sample, and dehydration during sampling. These problems have been solved by adjustments in technique so that within any one given experiment the tenderness evaluation can be kept very uniform. The greatest problem in tenderness evaluation—whether by panel or machine—is that the samples have always had to be cooked. Nothing in the literature reviewed suggests any degree of success obtained by testing raw poultry meat. If meat could be tested raw, it would eliminate the time, cost and possible source of variation in-
184
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 10, 2015
'"TpENDERNESS measurement is a rela-*- tive evaluation of one of the most important quality factors in meat. Two methods are commonly employed. The first is the organoleptic panel where each member is given a sample to evaluate—either by the number of chews required to masticate the meat or by ranking judgment on some sort of decanoic scale. With even a small panel of conscientious members a good relative evaluation can be obtained. This is considered to be the most accurate evaluation of tenderness. Tenderness is also measured by machine. Several mechanical devices are available for just such a purpose. However, none of these machines appear to be able to simulate the true action of a chewing mouth, and consequently each approximates that action with only a certain degree of success. Of the mechanical devices used the Warner Bratzler shear machine has been most widely reported, but the best relationships between a mechanical device and a competent panel have been established with the Kramer shear press. Deatherage and Garnatz (1952) reported that a poor correlation existed between the Warner Bratzler shear machine and a competent panel when working with beef. Bochian, Anglemier and Sather (1958) found a good but negative correlation (r = .65) between a taste panel and a grinder method of tenderness measurement. Shannon, Marion and Stadelman (1957) reported a correlation of
TENDERNESS EVALUATION
curred during the cooking process. Consequently, the purpose of this study was to find out if good tenderness evaluation could be obtained by the shearing of raw meat, on the Kramer shear press. EXPERIMENTAL PROCEDURE
toralis major muscle was packaged in polyethylene and frozen at 0 degrees F. After thawing the meat for eight hours at room temperature (65 degrees F.) four uniform samples weighing two grams each were cut from each muscle for a panel evaluation. The panel consisted of four trained members and each member scored the sample by the number of chews necessary before swallowing—including the swallowing chew. Thus on each bird 12 evaluations were made, or a total of 300 evaluations for the complete experiment, including 100 raw shearing evaluations, 100 cooked shearing evaluations, and 100 panel evaluations. For statistical analysis the four scores from each method of evaluation within each bird were matched at random and correlated. The correlations were calculated for different aging periods to determine any existing relationships that might prove worthwhile to note. Experiment 2. Twelve, 24-week-old, Broad White turkeys were used in this experiment. The birds were slaughtered by the same method used in Experiment 1. Four birds each were aged in slush ice for periods of 2 hours, 6 hours, and 10 hours. Samples were obtained by the same method as in Experiment 1 with the exception that for every bird tested three samples were obtained for raw shearing, three for cooked shearing, and three for panel evaluation of each size—one gram, two grams, and three grams. Three panel members were employed. For analysis, averages were taken on each bird for each method of evaluation. These averages were analyzed by correlation. RESULTS AND DISCUSSION Experiment 1. The results of the analysis of this experiment may be seen on Table 1. From Table 1 it can be seen that in
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 10, 2015
Experiment 1. A sampling device was constructed from high grade tool steel. This sampler was designed to cut a sample of meat 6.6 cm. long (the width of the testing cell of the Kramer shear press), 2.0 cm. wide and 1 cm. thick. Samples of uniform size could thus be obtained for shearing. Because of the possibility of variation in density of the meat the samples were still weighed to the nearest tenth of a gram and the shear score was calculated on the basis of shearing force required per gram of meat. Twenty-five, 35-week-old, Broad Breasted Bronze turkeys were used in the experiment. All birds were slaughtered by conventional methods, eviscerated, and chilled in slush ice. Five birds each were aged for periods of 2 hours, 6 hours, 10 hours, 16 hours, and 24 hours. At the end of the given aging periods the carcasses were removed from the slush ice and drained. The wings and legs were removed from the carcass as was one side of the breast. Four shearing evaluations were made immediately on each raw pectoralis major muscle obtained. The remaining side of the breast was enveloped with a two-sheet covering of .0015 gauge aluminum foil and roasted for 2 hours at 330 degrees F. in a reel-type oven. The cooked meat was cooled for 20 minutes before four evaluations were made on the cooked muscle in the same relative positions as the raw samples were obtained. On both the raw and cooked shearing evaluations the samples were extracted from as close to the center of the muscle as possible. The remaining cooked meat from the pec-
185
186
J. W. DODGE AND W. J. STADELMAN TABLE 1.—Results of correlation analysis in experiment 1 r values obtained Raw vs. cooked
Raw vs. panel
Cooked Degrees of vs. panel freedom
2 6 10 16 24 2 and 6 6 and 10 2,6 and 10 2,6,10,16 2,6,10,16,24
.2256 .3702 .2966 -.4896 .1 .4875 .6150 .7184 .6431 .6530
.3883 .1881 .1 .1695 .1 .4451 .3854 .5619 .5609 .5247
.5237 .6904 .3766 - .2966 .1 .6521 .6600 .7075 .6620 .6538
For significance , at .01 level* at 18 degrees of freedom r value = at 38 degrees of freedom r value = at 58 degrees of freedom r value = at 78 degrees of freedom r value = at 98 degrees of freedom r value = For significance at .05 level at 18 degrees of freedom r value = at 38 degrees of freedom r value =
18 18 18 18 18 38 38 58 78 98
.561 .405 .331 .307 .257 .444 .316
* Snedecor 1957.
many cases the r values are high—showing a good relationship between methods of evaluation. However the highest r value obtained is on the relationship between the raw shear and cooked shear at the 2, 6, and 10 hour periods. This r value is .7184. The predictability (R or r2) is only .516 or slightly over 50 percent. These r values are much lower than those reported by Shannon et al. (1957) and Wise (1957). Several factors could contribute to this result. First, a fatigue of the panel members was noticed during the panel evaluation. Possibly the sample size was large enough to produce considerable difference between the first and last evaluation in the test. Second, the previous reports are with chicken meat. The structure of turkey meat appears more gross and coarse, so possibly this would affect the results. Third, the method of statistical analysis could be improved. The samples for shearing were cut from the center of the muscle and the sam-
Aging time (hours) 2, 6, and 10
2, 6,10,16, and 24
Relationships
Degree of free- P r value dom .01»
rawXcooked shear raw shear Xpanel cooked shearXpanel
.7928 .7254 .9297
13 13 13
.641
raw Xcooked shear raw shearXpanel cooked shearXpanel
.7232 .7254 .8375
23 23 23
.505
* Snedecor, 1957.
pies for panel evaluation were cut from the area immediately surrounding this. Although the difference should be very small some variation could exist. The number of chews on the same muscle varied with the individual panel members. Therefore, it seemed wise to average the scores for the treatments and re-analyze the results. The results of this analysis may be seen on Table 2. The resulting r values as shown on Table 2 are much higher by this method of calculation. Several conclusions can be drawn from these results. First, although the relationship between raw shearing and chew panel appear high, the relationship between the cooked shear and the chew panel are even higher. This means that until some other method is devised for raw meat evaluation it is still not as good for research purposes as the cooked shear evaluation. Second, it may be noticed that at the longer aging periods the relationship is rather poor. One could conclude from this that as very small differences in tenderness arise the shear machine is not a good indication of the panel evaluation. It would consequently appear that for the time being if consumer acceptability of cooked meat is to be estimated, then the evaluation should be made on cooked meat. Again the question arises as to what effect cooking has on tenderization. The matter of sample
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 10, 2015
Aging period testedhours
TABLE 2.—Results of correlation between raw shear, cooked shear, and panel evaluation averages for each bird at selected aging times in experiment 1
187
TENDERNESS EVALUATION TABLE 3.—Relationships between raw and cooked shear measurements and panel evaluations on three sample sizes of cooked turkey meat —All relationships being shown for aging periods of 2 hours, 6 hours, and 10 hours DcETCCS
Treatments
r values
Raw shear vs. cooked shear Raw shear vs. 1-gram chew Raw shear vs. 2-gram chew Raw shear vs. 3-gram chew Cooked shear vs. 1-gram chew Cooked shear vs. 2-gram chew Cooked shear vs. 3-gram chew
.8724 .6933 .7582 . 6992 . 8041 .7461 .8050
of P .01 P .05* freedom 10 10 10 10 10 10 10
.708 .708 .708 .708 .708 .708 .708
.576 .576 .576 .576 .576 .576 .576
size had still not been investigated, so another experiment was designed to look into this. Experiment 2. The results of Experiment 2 are shown in Table 3. An interesting point arises from the results as shown in Table 3. On the raw shearing the highest correlation was with the two-gram chew, while on the cooked shearing this particular relationship provided the lowest correlation. The reasoning behind this is hard to explain, unless it is because of the limited number of samples employed. Nevertheless in each case there is close proximity between the shearing and one-gram chew and three-gram chew evaluation relationships. On these particular sized samples the correlation between shearing and chewing is much higher for the cooked samples. Thus a small difference is noticeable between sample size with no particular trend involved. SUMMARY
In this study 37 turkeys were used to study tenderness evaluation by shearing both raw and cooked samples on the Kramer shear press. The shear scores were
REFERENCES Bockian, A. H., A. F. Englemier and L. A. Sather, 19S8. A comparison of and objective subjective measurement of beef tenderness. Food Technol. 12: 483-485. Cameron, J. K., and E. A. Ryan, 19SS. Tenderness in poultry meat I. An improved method of measuring. Food Technol. 9: 29. Deatherage, F. E., and G. Garnatz, 19S2. A comparative study of tenderness by sensory panel and by shear strength measurements. Food Technol. 6: 260-262. Dodge, J. W., and W. J. Stadelman, 1959. Postmortem aging of poultry meat and its effect on the tenderness of the breast muscles. Food Technol. 13: 81-84. Shannon, W. G., W. W. Marion and W. J. Stadelman, 1957. Effect of temperature and time of scalding on the tenderness of the breast meat of chicken. Food Technol. 11: 284-286. Snedecor, G. W., 1957. Statistical Methods, Fifth Edition, Iowa State College Press, Ames, Iowa. Wise, R. G., 1957. Effect of beating by mechanical pickers on the tenderness of poultry meat. A thesis, M.S., Purdue University. Lafayette, Indiana.
March 31, April 1-2. Pacific Dairy and Poultry Association Annual Convention, Las Vegas, Nevada. April 11-13. Poultry and Egg National Board, Annual Meeting, La Salle Hotel, Chicago, Illinois.
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 10, 2015
* Snedecor, 1957.
compared to evaluations made by a competent chew panel. In the first experiment four samples were sheared raw, four were sheared cooked, and four cooked samples were evaluated by the panel on each bird. The results indicated that although significant correlations were produced between raw shearing and the panel evaluation of the cooked samples on the same carcass, the relationship was not as high as that found between cooked sample shearing and the panel evaluations. In the second experiment it was found that the size of sample offered to the panel may influence the relationships found in such a study but no particular trend in respect to the effect of size on the relationship was evident.