Sarcomere Length: The average sarcomere length values for ES and nonES (NES), LD and SM muscles of mutton tissue were 1.85, 1.84 1.79, and 1.80 mm, respectively. The main effects of ES and muscle type did not have a significant effect on sarcomere length. When the average pH value of both muscles was dropped to below 6, the temperature was approximately 12oC. So, the results revealed that the carcasses used in this research were not exposed to cold shortening. Bendall (1972) defined conditions which cause cold shortening (muscle temperature below 11°C before the pH has fallen below 6.2) and based on these criteria, cold shortening should not have been present in these animals.
Sensory Evaluation and Fragmentation Index: The least square means (with standard deviations) of scores for panel tenderness, juiciness, residue remaining after chewing, number of chews, and fragmentation index scores are presented in Table 1. Analysis of variance revealed that interactions among main factors (ES and muscles) were not significant (P > 0.05). As indicated in Table 1, electrical stimulation improved panel tenderness scores of mutton at the P < 0.06 level. The lack of the more traditional significance level might have been due to the limited number of animals that were evaluated by the sensory evaluation test. Also, the conditions of this research did not allow cold shortening to occur. These results were in the same direction as the findings of cited references (Solomon and Lynch, 1988; Vijayakumar et al., 1990; Mahajan and Panda, 1991; Reddy et al., 1991), but the present differences were not large enough to be statistically significant. Solomon and Lynch (1988) reported that tenderness panel score for young ram lambs was improved by ES, but the juiciness score was not influenced. In the same research, the number of chews before swallowing was reduced from fifty-three to thirty-three chews by ES. Also, tenderness scores for sheep carcasses were significantly increased (P < 0.05) by using ES in the studies of Mahajan and Panda (1991) and Reddy et al. (1991).
| Table 1. Least square means and standard deviation for the effects of electrical stimulation and muscles on some quality parameters of mutton tissue. | ||||||
| Panel Tenderness5 |
Panel Juiciness6 |
Residue After Chewines7 |
Number of Chewines8 |
Fragmentation Index9 |
Cooking Loss(%) |
|
| Electrical Stimulation | *10 | NS 11 | NS | NS | NS | NS |
| ES1 | 5.54 ± 0.38 | 4.95 ± 0.17 | 5.42 ± 0.28 | 44.63 ± 2.51 | 375.8 ± 28.4 | 29.6 ± 0.85 |
| NES2 | 4.52 ± 0.38 | 4.71 ± 0.17 | 5.70 ± 0.28 | 49.38 ± 2.57 | 412.1 ± 28.4 | 28.1 ± 0.83 |
| Muscles | * | NS | NS | NS | NS | * |
| LD3 | 5.65 ± 0.38 | 4.91 ± 0.17 | 5.33 ± 0.29 | 43.67 ± 2.37 | 357.7 ± 28.4 | 26.8 ± 0.83 |
| SM4 | 4.40 ± 0.38 | 4.75 ± 0.17 | 5.78 ± 0.28 | 50.34 ± 2.51 | 430.2 ± 28.4 | 30.9 ± 0.85 |
| 1ES = Electrically stimulated, 2NES = Not electrically stimulated, 3LD = Longissimus dorsi, 4SM = Semimembranosus, 5Scored on a scale of 1-9 [(extremely tough (1) to extremely tender (9)], 6Scored on a scale of 1-9 [extremely dry (1) to extremely juicy (9)], 7Scored on a scale of 1-9 [(a few (1) to a lot (9)], 8Number of chews was determined by panel members before meat sample was broken up and swallowed, 9As fragmentation index increases, meat becomes less tender and vice versa. 10ES is significant at the (P < 0.06) level, 11NS = Treatments are not significantly different (P > 0.05), * Treatments are significantly different (P < 0.05). | ||||||
However, the influence of muscle type (LD versus SM) on the panel tenderness score was statistically significant (Table 1), and the SM was less tender than the LD. The result was supported by the result of Taylor and Marshall (1980) and Mederios et al. (1989). Also the cooking losses were significantly different for the LD and SM muscles and were higher for the SM muscle as can be seen in Table 1. The loss of moisture during cooking might account for the tenderness differences. Juiciness was not significantly different due to ES or muscle type.