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Heme Pigment Levels in Chicken Broilers Chilled in Ice Slush and Air1
Heme Pigment Levels in Chicken Broilers Chilled in Ice Slush and Air 1 B. K. FLEMING, G. W. FRONING, and T. S. YANG Department of Food Science and Technology, University of Nebraska, Lincoln, Nebraska 68583-0919 (Received for publication April 10, 1991) ABSTRACT Ice-slush-chilled versus air-chilled broilers were studied for differences in the heme pigment levels in the gizzard, breast, and thigh muscles. Significant differences (P<05) were observed in pigment levels among the breast, thigh, and gizzard. However, no significant effects on hemoglobin and myoglobin levels were observed between chilling methods. There was a significant difference (P<05) in cytochrome c levels between chilling methods. The observed difference in cytochrome c levels may be a contributing factor in the development of color problems in either fresh or processed poultry meat. Hunterlab L values were significantly (P<.05) negatively correlated (r >-.97) and t^ values were significantly positively correlated (r>.85) with the total heme pigment levels present in the breast muscle. (Key words: heme pigments, ice slush chilling, air chilling, broilers, cytochrome c levels) 1991 Poultry Science 70:2197-2200 INTRODUCTION
Within the last 15 yr, health conscious Americans have demanded a larger variety of low-fat meat products. This demand has led to an increased consumption of fresh poultry meats and further processed poultry products. Consumer acceptance of these processed products has been linked to many factors, one of the most significant being product color. A pink color in cooked white poultry muscle has been considered to be highly undesirable to the consumer. Poultry meat color is influenced by age, sex, and strain (Froning et al, 1968a), diet of the bird (Froning et al, 1969a), intramuscular fat (Janky and Froning, 1973), moisture content of the meat (Froning et al., 1968b), preslaughter factors (Froning et al., 1969b; Ngoka et al., 1982), processing variables, and the level of heme pigments present in the meat (Lawrie, 1966; Pikul et al, 1986; Cornforth et al, 1986; Ann and Maurer, 1989). Heme pigment concentrations found in the muscle can greatly affect overall muscle color (Drabkin, 1950). It has been shown that, when compared with other species, the concentration of myoglobin was lower in avian tissues, with
'Published as Paper Number 9552, Journal Series, Nebraska Agricultural Division. 2 Midwest Processing Systems, Minneapolis, MN 55410.
correspondingly higher levels of hemoglobin and cytochrome c (Drabkin, 1950). Cytochrome c is present in all organisms having mitochondrial respiratory chains (Tsou, 1951). Additionally, it has been shown that cytochrome c is extremely heat-stable and can withstand denaturation temperatures as high as 105 C (Cornish and Froning, 1974). Narasubhai and Kallapur (1977) reported a greater concentration of cytochrome c in active muscles. Air chilling is commonly used in Europe but ice slush chilling predominates in the United States. Chilling methods may affect heme pigment concentrations in the muscle. Therefore, the objective of the present research was to investigate the effect of postslaughter chilling methods on muscle pigment concentrations. MATERIALS AND METHODS
Forty 6-wk-old chicken broilers (VantressArbor Acres strain) were used and the study was replicated twice (20 birds per repucate). Birds from each replicate were grown out at different times. The slaughter was accomplished using procedures outlined by Mountney (1976). The birds were immobilized using a Cervin FS stunner2 at a setting of 4 (80 mA) and a modified Kosher cut was used for exsanguination. The birds were allowed to bleed for about 90 s. Scalding was accomplished in 58.5 C water for 45 s, with
2197
2198
FLEMING ET AL. TABLE 1. Effect (x ± SEM) of chilling conditions on Hunterlab valuer of chicken broiler musclef
Hunterlab value L value
aL value
1>L value
Muscle Breast Thigh Gizzard Breast Thigh Gizzard Breast Thigh Gizzard
Air chilled
Ice slush
41.18 36.99 30.02 2.24 5.67 8.12 5.20 5.10 4.05
± ± ± ± ± ± ± ± ±
a
.96 l.l b 1.3' .27° .26b .40" .49° .59b .31°
41.65 38.19 29.59 2.56 5.87 7.34 5.81 5.25 3.61
± ± ± ± ± ± ± ± ±
.84" .89b 1.1' .23' .20b .17a .51* .49b .27°
a_c
Means with no common superscripts within a variable and chilling condition are significantly different at the 5% level. 'Chilling conditions did not significantly afreet Hunterlab values. 2 A Hunterlab Tristimulus Colorimeter Model D25M-9 (Hunterlab Associates Laboratory, Inc., Reston, VA 22090) was used to obtain triplicate measurements of L, aj__, and DL values where L = lightness, aj, = redness, and bj_ = yellowness. The colorimeter was standardized using a pink standard Number C2-6071 having an L value of 68.91, an a^ value of 21.50, and a DL value of 10.75. 3 Twenty observations per mean included pooled replicates (10 birds per replicate).
defeathering and evisceration completed following approved USDA guidelines as reported by Mountney (1976). As the birds left the processing line, the first 10 were placed in an ice slush tank, and the final 10 were placed in an open plastic bag and stored in a 5 C cold room with a forced-air system. Both groups were held for 12 h during which time an internal temperature of 5 C was attained. Following this chilling period, the breast and thigh muscles from each bird were hand deboned and held with the gizzard at -15 C approximately 3 mo for further analysis. A Hunterlab Tristimulus Colorimeter (Model D25M-9)3 was used to obtain triplicate measurements of L (lightness), aj, (redness), and DL (yellowness) values of the Pectoralis minor muscle of the breast, the Biceps femoris muscle of the thigh, and the gizzard. Samples for color measurement were prepared as reported by Froning et al. (1986). Color values were measured on freshly sliced interior surfaces of the P. minor muscle of the breast, the B. femoris of the thigh muscle, and the gizzard. The colorimeter was standardized using a pink standard (Number C2-6071) having an L value of 68.91, an a^ value of 21.50, and a DL value of 10.75.
^Hunterlab Associates Laboratory, Inc., Reston, VA 22090.
Total heme pigments, myoglobin, and hemoglobin concentrations were measured using the procedure of Fleming et al. (1960). Cytochrome c concentration in the various muscles was determined using the method of Pikul et al. (1986). These measurements were analyzed in duplicate on the breast muscle, thigh muscle, and the gizzard. For each variable studied, an ANOVA was used to determine statistical significance (SAS Institute, 1979). Color data and heme pigment analyses were statistically analyzed using a completely randomized design with chilling method or muscle as the only main effect. Treatment effects were tested against the residual error term because there were no significant replicate by treatment interactions. Pearson's Correlation Coefficient (SAS Institute, 1979) was also employed to determine any correlation between Hunterlab color measurements and pigment concentrations. RESULTS AND DISCUSSION
Because there was no significant replicate by treatment interaction, replicates were combined. When analyzing Hunterlab measurements (Table 1), it was determined that there were no significant differences (P>.05) in L, a^ and DL measurements when examining the same muscle between chilling methods. However, there was a significant difference (P<.05) in Hunterlab color measurements when com-
2199
PIGMENTS IN CHILLED BROILERS
TABLE 2. Effect (x ± SEM) of chilling conditions on total heme, hemoglobin, myoglobin, and cytochrome concentrations in chicken muscle^ Muscle
Total heme
Hemoglobin
Myoglobin
(mg/g)
Cytochrome (Ug/g)
Breast Thigh Gizzard
.32 ± .M0-* .59 ± .OS^ 4.04 ± . 1 4 ^
Ice slush chilling .17 ± .04 c * .15 ± .02 c * b .38 ± .04 -* .21 ± .(a** 1.97 ± .ll"-* 2.07 ± .13"-*
Breast Thigh Gizzard
.44 ± .04c,x .79 ± .07b-* 4.03 ± A4*x
.28 ± .05c-* .48 ± .(H** 1.88 ± . 1 4 ^
13.71 ± .64c-y 37.38 ± 1.2b-v 92.84 ± 2.0E-y
Air chilling — .16 ± .02c-* .30 ± .03 b,x 2.15 ± .lO3-*
27.15 ± .92c-* 65.99 ± 1.4b-* 147.55 ± SA**
a-c Means with no common superscripts within the same column of the same chilling group are significantly different at the 5% level. "^Means with no common superscripts within the same column and muscle (comparison of chilling methods) are significantly different at the 5% level. 'Twenty observations per mean included pooled replicates (10 birds per replicate).
paring different muscles. It was found that the breast had higher L values and lower ai, values than either the thigh or the gizzard, as shown in previous research (Froning etal., 1968a). As expected, the gizzard L values were significantly lower (darker) (P<05) and the a^ values were significantly higher (more red) (P<.05) man either the breast or thigh muscles. These findings are similar to previous work concerning Hunterlab measurements of turkey muscles (Froning et al., 1968a). Overall, the present results indicated that die chilling method had no direct relationship with Hunterlab color values. There were no significant differences (P<.05) in the concentrations of total heme pigments, hemoglobin, or myoglobin between chilling methods (Table 2). However, there was a significant difference (P<.05) in pigment concentrations among muscles, which agrees with the results reported by Cornish and Froning (1974). The breast muscle had the lowest concentration of total heme pigments, hemoglobin, and cytochrome c, with the thigh muscle and gizzard exhibiting progressively higher levels, respectively. The concentration of cytochrome c in all muscles tested (Table 2) was significantly different (P<.05) between chilling methods. There was almost twice as much cytochrome c in the air-chilled birds compared with the iceslush-chilled birds. The cytochrome c concentrations present in the breast and thigh muscle of the ice-slush-chilled birds were very similar to uiose reported by Pikul et al. (1986), who
observed 11.4 and 35.5 ug/g, respectively, in the breast and thigh muscle of chicken broilers. To partially explain the difference in cytochrome c concentrations between chilling methods, it was hypothesized that the mitochondria in which cytochrome c is found, may have been disrupted during the ice-slush chilling, which may have caused a release of cytochrome c from the cell. Differences in the cytochrome c content may also be due to a leaching effect. Because cytochrome pigments are substantially less prone to heat damage (Cornish and Froning, 1974), they perhaps remain more soluble and less subject to damage from scalding temperatures than other heme pigments. Dilution of pigments may be a factor, although Froning et al. (1960) reported that moisture content of chicken broiler meat was not influenced by chilling, because much of the additional moisture was lost through the drip. There was also a significant difference (P<05) in cytochrome c levels among die breast, thigh, and gizzard, which was similar to the results of Pikul et al. (1986). There was a significant negative correlation (r>-.97) between total heme pigments and Hunterlab L values (Table 3). As the pigment concentration of the muscle decreased, the corresponding L or lightness value of the muscle increased. Additionally, there was a significant positive correlation (r>.85) between total heme pigments and Hunterlab aL values. As pigment concentrations increased, a corresponding increase in aL values (more redness) was observed, which agrees with similar data
2200
FLEMING ET AL.
TABLE 3. Pearson correlation coefficients between breast muscle heme pigments and Hunterlab L valuer" Hunterlab L values Variable
Correlation coefficient
Total hemes Hemoglobin Myoglobin Cytochrome c
-.97 -.97 -.96 -.91
Hunterlab a^ values
Probability
Correlation coefficient
Probability
.001 .002 .002 .013
.85 .84 .81 .82
.03 .04 .05 .04
*A Hunterlab Tristimulus Colorimeter Model 025 M-9 (Hunterlab Associates Laboratory, Inc., Reston, VA 22090) was used to obtain triplicate measurements of L, a^, and DL values where L = lightness, a^ = redness, and b^ = yellowness. The colorimeter was standardized using a pink standard Number C2-6071 having an L value of 68.91, an a L value of 21.50, and a DL value of 10.75. 2 Twenty observations per group included pooled replicates (10 birds each replicate).
reported in turkey muscle by Froning et al. (1968a). The present results indicated that chilling methods may influence the cytochrome c content of chicken meat. Although chilling methods did not significantly affect the Hunterlab values of raw meat, the increase in cytochrome c content of air-chilled muscles may become significant in cooked meat. As reported by Cornish and Froning (1974), cytochrome c pigments are quite heat-stable. Thus, the higher level of cytochrome c in airchilled muscle may lead potentially to pink color problems in further processed chicken products. REFERENCES Ahn, D. U„ and A. J. Maurer, 1989. Effects of added pigments, soft, and phosphate on color extractable pigments, total pigment, and oxidation-reduction potential in turkey breast meat. Poultry Sci. 68: 1088-1099. Comforth, D. P., F. Vahabzadeh, C. E. Carpenter, and D. T. Bartholemew, 1986. Role of reduced hemochromes in pink color defect of cooked turkey rolls. J. Food Sci. 51:1132-1134. Cornish, D. P., and G. W. Froning, 1974. Isolation and purification of turkey heme proteins. Poultry Sci. 53: 365-377. Drabkin, D. L., 1950. The distribution of chromoproteins, hemoglobin, myoglobin and cytochrome c in the tissues of different species, and the relationship of the total content of each chromoprotein to body mass. J. Biol. Chem. 182:317-333. Fleming, H. P., T. N. Blumer, and H. B. Craig, 1960. Quantitative estimations of myoglobin and hemoglobin in beef muscle extracts. J. Anim. Sci. 19: 1164-1171. Froning, G. W., J. C. Acton, H. R. Ball C. J. Brekke, R. J. Hasiak, and N. A. Cox, 1986. Recommended methods for the analysis of eggs and poultry meat— an annotated bibliography. North Central Regional Bulletin No. 307, Agricultural Research Division,
University of Nebraska, Lincoln, NE. Froning, G. W., J. Daddario, and T. E. Hartung, 1968a. Color and myoglobin concentration in turkey meat as affected by age, sex, and strain. Poultry Sci. 47: 1827-1835. Froning, G. W., J. Daddario, T. E. Hartung, T. E. Sullivan, and R. M. Hill, 1969a. Color of poultry meat as influenced by dietary nitrate and nitrite. Poultry Sci. 48:668-674. Froning, G. W., G. Hargus, and T. E. Hartung, 1968b. Color and texture of ground turkey meat products as affected by dried egg white solids. Poultry Sci. 47: 1187-1194. Froning, G. W., F. B. Mather, J. Daddario, and T. E. Hartung, 1969b. Effect of automobile exhaust fume inhalation by poultry immediately prior to slaughter on color of meat. Poultry Sci. 48:485-487. Froning, G. W., M H. Swanson, and H. N. Benson, 1960. Moisture levels in frozen poultry as related to thawing losses, cooking losses, and palatability. Poultry Sci. 39:373-377. Janky, D. M., and G. W. Froning, 1973. The effect of pH and certain additives on heat denaturation of turkey meat myoglobin. Poultry Sci. 52:152-159. Lawrie, R. A., 1966. Meat Science. Pergamon Press. New York, NY. Mountney, G. J., 1976. Poultry Products Technology. AVI Publishing Co., Inc., Westport, CT. Narasubhai, A. V., and V. L. Kallapur, 1977. Correlation between cytochrome c and myoglobin contents of the different leg muscles and Musculus pectoralis with reference to sex of the domestic fowl. Current Sci. 46:269-270. Ngoka, D. A., G. W. Froning, S. R. Lowry, and A. S. Babji, 1982. Effects of sex, age, preslaughter factors, and holding conditions on the quality characteristics and chemical composition of turkey breast muscles. Poultry Sci. 61:1996-2003. Pikul, J., A. Niewiarowicz, and H. Kupijaj, 1986. The cytochrome c content of various poultry meats. J. Sci. Food Agric. 37:1236-1240. SAS Institute, 1979. SAS® User's Guide, 1979 ed. SAS Institute, Inc., Cary, NC. Tsou, C. L., 1951. Cytochrome c modified by digestion with proteolytic enzymes. I. Digestion. Biochem. J. 49:362-367.
Within the last 15 yr, health conscious Americans have demanded a larger variety of low-fat meat products. This demand has led to an increased consumption of fresh poultry meats and further processed poultry products. Consumer acceptance of these processed products has been linked to many factors, one of the most significant being product color. A pink color in cooked white poultry muscle has been considered to be highly undesirable to the consumer. Poultry meat color is influenced by age, sex, and strain (Froning et al, 1968a), diet of the bird (Froning et al, 1969a), intramuscular fat (Janky and Froning, 1973), moisture content of the meat (Froning et al., 1968b), preslaughter factors (Froning et al., 1969b; Ngoka et al., 1982), processing variables, and the level of heme pigments present in the meat (Lawrie, 1966; Pikul et al, 1986; Cornforth et al, 1986; Ann and Maurer, 1989). Heme pigment concentrations found in the muscle can greatly affect overall muscle color (Drabkin, 1950). It has been shown that, when compared with other species, the concentration of myoglobin was lower in avian tissues, with
'Published as Paper Number 9552, Journal Series, Nebraska Agricultural Division. 2 Midwest Processing Systems, Minneapolis, MN 55410.
correspondingly higher levels of hemoglobin and cytochrome c (Drabkin, 1950). Cytochrome c is present in all organisms having mitochondrial respiratory chains (Tsou, 1951). Additionally, it has been shown that cytochrome c is extremely heat-stable and can withstand denaturation temperatures as high as 105 C (Cornish and Froning, 1974). Narasubhai and Kallapur (1977) reported a greater concentration of cytochrome c in active muscles. Air chilling is commonly used in Europe but ice slush chilling predominates in the United States. Chilling methods may affect heme pigment concentrations in the muscle. Therefore, the objective of the present research was to investigate the effect of postslaughter chilling methods on muscle pigment concentrations. MATERIALS AND METHODS
Forty 6-wk-old chicken broilers (VantressArbor Acres strain) were used and the study was replicated twice (20 birds per repucate). Birds from each replicate were grown out at different times. The slaughter was accomplished using procedures outlined by Mountney (1976). The birds were immobilized using a Cervin FS stunner2 at a setting of 4 (80 mA) and a modified Kosher cut was used for exsanguination. The birds were allowed to bleed for about 90 s. Scalding was accomplished in 58.5 C water for 45 s, with
2197
2198
FLEMING ET AL. TABLE 1. Effect (x ± SEM) of chilling conditions on Hunterlab valuer of chicken broiler musclef
Hunterlab value L value
aL value
1>L value
Muscle Breast Thigh Gizzard Breast Thigh Gizzard Breast Thigh Gizzard
Air chilled
Ice slush
41.18 36.99 30.02 2.24 5.67 8.12 5.20 5.10 4.05
± ± ± ± ± ± ± ± ±
a
.96 l.l b 1.3' .27° .26b .40" .49° .59b .31°
41.65 38.19 29.59 2.56 5.87 7.34 5.81 5.25 3.61
± ± ± ± ± ± ± ± ±
.84" .89b 1.1' .23' .20b .17a .51* .49b .27°
a_c
Means with no common superscripts within a variable and chilling condition are significantly different at the 5% level. 'Chilling conditions did not significantly afreet Hunterlab values. 2 A Hunterlab Tristimulus Colorimeter Model D25M-9 (Hunterlab Associates Laboratory, Inc., Reston, VA 22090) was used to obtain triplicate measurements of L, aj__, and DL values where L = lightness, aj, = redness, and bj_ = yellowness. The colorimeter was standardized using a pink standard Number C2-6071 having an L value of 68.91, an a^ value of 21.50, and a DL value of 10.75. 3 Twenty observations per mean included pooled replicates (10 birds per replicate).
defeathering and evisceration completed following approved USDA guidelines as reported by Mountney (1976). As the birds left the processing line, the first 10 were placed in an ice slush tank, and the final 10 were placed in an open plastic bag and stored in a 5 C cold room with a forced-air system. Both groups were held for 12 h during which time an internal temperature of 5 C was attained. Following this chilling period, the breast and thigh muscles from each bird were hand deboned and held with the gizzard at -15 C approximately 3 mo for further analysis. A Hunterlab Tristimulus Colorimeter (Model D25M-9)3 was used to obtain triplicate measurements of L (lightness), aj, (redness), and DL (yellowness) values of the Pectoralis minor muscle of the breast, the Biceps femoris muscle of the thigh, and the gizzard. Samples for color measurement were prepared as reported by Froning et al. (1986). Color values were measured on freshly sliced interior surfaces of the P. minor muscle of the breast, the B. femoris of the thigh muscle, and the gizzard. The colorimeter was standardized using a pink standard (Number C2-6071) having an L value of 68.91, an a^ value of 21.50, and a DL value of 10.75.
^Hunterlab Associates Laboratory, Inc., Reston, VA 22090.
Total heme pigments, myoglobin, and hemoglobin concentrations were measured using the procedure of Fleming et al. (1960). Cytochrome c concentration in the various muscles was determined using the method of Pikul et al. (1986). These measurements were analyzed in duplicate on the breast muscle, thigh muscle, and the gizzard. For each variable studied, an ANOVA was used to determine statistical significance (SAS Institute, 1979). Color data and heme pigment analyses were statistically analyzed using a completely randomized design with chilling method or muscle as the only main effect. Treatment effects were tested against the residual error term because there were no significant replicate by treatment interactions. Pearson's Correlation Coefficient (SAS Institute, 1979) was also employed to determine any correlation between Hunterlab color measurements and pigment concentrations. RESULTS AND DISCUSSION
Because there was no significant replicate by treatment interaction, replicates were combined. When analyzing Hunterlab measurements (Table 1), it was determined that there were no significant differences (P>.05) in L, a^ and DL measurements when examining the same muscle between chilling methods. However, there was a significant difference (P<.05) in Hunterlab color measurements when com-
2199
PIGMENTS IN CHILLED BROILERS
TABLE 2. Effect (x ± SEM) of chilling conditions on total heme, hemoglobin, myoglobin, and cytochrome concentrations in chicken muscle^ Muscle
Total heme
Hemoglobin
Myoglobin
(mg/g)
Cytochrome (Ug/g)
Breast Thigh Gizzard
.32 ± .M0-* .59 ± .OS^ 4.04 ± . 1 4 ^
Ice slush chilling .17 ± .04 c * .15 ± .02 c * b .38 ± .04 -* .21 ± .(a** 1.97 ± .ll"-* 2.07 ± .13"-*
Breast Thigh Gizzard
.44 ± .04c,x .79 ± .07b-* 4.03 ± A4*x
.28 ± .05c-* .48 ± .(H** 1.88 ± . 1 4 ^
13.71 ± .64c-y 37.38 ± 1.2b-v 92.84 ± 2.0E-y
Air chilling — .16 ± .02c-* .30 ± .03 b,x 2.15 ± .lO3-*
27.15 ± .92c-* 65.99 ± 1.4b-* 147.55 ± SA**
a-c Means with no common superscripts within the same column of the same chilling group are significantly different at the 5% level. "^Means with no common superscripts within the same column and muscle (comparison of chilling methods) are significantly different at the 5% level. 'Twenty observations per mean included pooled replicates (10 birds per replicate).
paring different muscles. It was found that the breast had higher L values and lower ai, values than either the thigh or the gizzard, as shown in previous research (Froning etal., 1968a). As expected, the gizzard L values were significantly lower (darker) (P<05) and the a^ values were significantly higher (more red) (P<.05) man either the breast or thigh muscles. These findings are similar to previous work concerning Hunterlab measurements of turkey muscles (Froning et al., 1968a). Overall, the present results indicated that die chilling method had no direct relationship with Hunterlab color values. There were no significant differences (P<.05) in the concentrations of total heme pigments, hemoglobin, or myoglobin between chilling methods (Table 2). However, there was a significant difference (P<.05) in pigment concentrations among muscles, which agrees with the results reported by Cornish and Froning (1974). The breast muscle had the lowest concentration of total heme pigments, hemoglobin, and cytochrome c, with the thigh muscle and gizzard exhibiting progressively higher levels, respectively. The concentration of cytochrome c in all muscles tested (Table 2) was significantly different (P<.05) between chilling methods. There was almost twice as much cytochrome c in the air-chilled birds compared with the iceslush-chilled birds. The cytochrome c concentrations present in the breast and thigh muscle of the ice-slush-chilled birds were very similar to uiose reported by Pikul et al. (1986), who
observed 11.4 and 35.5 ug/g, respectively, in the breast and thigh muscle of chicken broilers. To partially explain the difference in cytochrome c concentrations between chilling methods, it was hypothesized that the mitochondria in which cytochrome c is found, may have been disrupted during the ice-slush chilling, which may have caused a release of cytochrome c from the cell. Differences in the cytochrome c content may also be due to a leaching effect. Because cytochrome pigments are substantially less prone to heat damage (Cornish and Froning, 1974), they perhaps remain more soluble and less subject to damage from scalding temperatures than other heme pigments. Dilution of pigments may be a factor, although Froning et al. (1960) reported that moisture content of chicken broiler meat was not influenced by chilling, because much of the additional moisture was lost through the drip. There was also a significant difference (P<05) in cytochrome c levels among die breast, thigh, and gizzard, which was similar to the results of Pikul et al. (1986). There was a significant negative correlation (r>-.97) between total heme pigments and Hunterlab L values (Table 3). As the pigment concentration of the muscle decreased, the corresponding L or lightness value of the muscle increased. Additionally, there was a significant positive correlation (r>.85) between total heme pigments and Hunterlab aL values. As pigment concentrations increased, a corresponding increase in aL values (more redness) was observed, which agrees with similar data
2200
FLEMING ET AL.
TABLE 3. Pearson correlation coefficients between breast muscle heme pigments and Hunterlab L valuer" Hunterlab L values Variable
Correlation coefficient
Total hemes Hemoglobin Myoglobin Cytochrome c
-.97 -.97 -.96 -.91
Hunterlab a^ values
Probability
Correlation coefficient
Probability
.001 .002 .002 .013
.85 .84 .81 .82
.03 .04 .05 .04
*A Hunterlab Tristimulus Colorimeter Model 025 M-9 (Hunterlab Associates Laboratory, Inc., Reston, VA 22090) was used to obtain triplicate measurements of L, a^, and DL values where L = lightness, a^ = redness, and b^ = yellowness. The colorimeter was standardized using a pink standard Number C2-6071 having an L value of 68.91, an a L value of 21.50, and a DL value of 10.75. 2 Twenty observations per group included pooled replicates (10 birds each replicate).
reported in turkey muscle by Froning et al. (1968a). The present results indicated that chilling methods may influence the cytochrome c content of chicken meat. Although chilling methods did not significantly affect the Hunterlab values of raw meat, the increase in cytochrome c content of air-chilled muscles may become significant in cooked meat. As reported by Cornish and Froning (1974), cytochrome c pigments are quite heat-stable. Thus, the higher level of cytochrome c in airchilled muscle may lead potentially to pink color problems in further processed chicken products. REFERENCES Ahn, D. U„ and A. J. Maurer, 1989. Effects of added pigments, soft, and phosphate on color extractable pigments, total pigment, and oxidation-reduction potential in turkey breast meat. Poultry Sci. 68: 1088-1099. Comforth, D. P., F. Vahabzadeh, C. E. Carpenter, and D. T. Bartholemew, 1986. Role of reduced hemochromes in pink color defect of cooked turkey rolls. J. Food Sci. 51:1132-1134. Cornish, D. P., and G. W. Froning, 1974. Isolation and purification of turkey heme proteins. Poultry Sci. 53: 365-377. Drabkin, D. L., 1950. The distribution of chromoproteins, hemoglobin, myoglobin and cytochrome c in the tissues of different species, and the relationship of the total content of each chromoprotein to body mass. J. Biol. Chem. 182:317-333. Fleming, H. P., T. N. Blumer, and H. B. Craig, 1960. Quantitative estimations of myoglobin and hemoglobin in beef muscle extracts. J. Anim. Sci. 19: 1164-1171. Froning, G. W., J. C. Acton, H. R. Ball C. J. Brekke, R. J. Hasiak, and N. A. Cox, 1986. Recommended methods for the analysis of eggs and poultry meat— an annotated bibliography. North Central Regional Bulletin No. 307, Agricultural Research Division,
University of Nebraska, Lincoln, NE. Froning, G. W., J. Daddario, and T. E. Hartung, 1968a. Color and myoglobin concentration in turkey meat as affected by age, sex, and strain. Poultry Sci. 47: 1827-1835. Froning, G. W., J. Daddario, T. E. Hartung, T. E. Sullivan, and R. M. Hill, 1969a. Color of poultry meat as influenced by dietary nitrate and nitrite. Poultry Sci. 48:668-674. Froning, G. W., G. Hargus, and T. E. Hartung, 1968b. Color and texture of ground turkey meat products as affected by dried egg white solids. Poultry Sci. 47: 1187-1194. Froning, G. W., F. B. Mather, J. Daddario, and T. E. Hartung, 1969b. Effect of automobile exhaust fume inhalation by poultry immediately prior to slaughter on color of meat. Poultry Sci. 48:485-487. Froning, G. W., M H. Swanson, and H. N. Benson, 1960. Moisture levels in frozen poultry as related to thawing losses, cooking losses, and palatability. Poultry Sci. 39:373-377. Janky, D. M., and G. W. Froning, 1973. The effect of pH and certain additives on heat denaturation of turkey meat myoglobin. Poultry Sci. 52:152-159. Lawrie, R. A., 1966. Meat Science. Pergamon Press. New York, NY. Mountney, G. J., 1976. Poultry Products Technology. AVI Publishing Co., Inc., Westport, CT. Narasubhai, A. V., and V. L. Kallapur, 1977. Correlation between cytochrome c and myoglobin contents of the different leg muscles and Musculus pectoralis with reference to sex of the domestic fowl. Current Sci. 46:269-270. Ngoka, D. A., G. W. Froning, S. R. Lowry, and A. S. Babji, 1982. Effects of sex, age, preslaughter factors, and holding conditions on the quality characteristics and chemical composition of turkey breast muscles. Poultry Sci. 61:1996-2003. Pikul, J., A. Niewiarowicz, and H. Kupijaj, 1986. The cytochrome c content of various poultry meats. J. Sci. Food Agric. 37:1236-1240. SAS Institute, 1979. SAS® User's Guide, 1979 ed. SAS Institute, Inc., Cary, NC. Tsou, C. L., 1951. Cytochrome c modified by digestion with proteolytic enzymes. I. Digestion. Biochem. J. 49:362-367.