| Summary: | 碩士 === 國立嘉義大學 === 動物科學系研究所 === 105 === The objective of this study was to determine calpain isoforms in turkey muscles and the postmortem calpain activity, desmin content and meat qualities of turkey breast muscle (pectoralis major). Ten turkey were slaughtered and the gizzard smooth muscle, cardiac and left breast muscles were removed from the carcasses in 10-15 min postmortem. The tissues were stored in liquid nitrogen immediately. The remainder of each carcass was packed in plastic bag and stored at 5 °C, sampling at 3, 6, 9 12, 24, 48 and 72 h postmortem from the right breast muscle. These samples were used to determine the pH value, calpain activity and desmin content. The pH meter and temperature probe were inserted into the center of the right breast muscle within 10-12 min after slaughter, measuring the changes of pH value and temperature within 3 h and 12 h postmortem. The right breast muscle was removed from the carcasses at 24 h postmortem for shear force, myofibril fragmentation index, colors and TBARS measurements. Results of casein zymography showed that turkey gizzard smooth muscle, cardiac and breast muscles have μ- and μ/m-calpain activity. The initial temperature in turkey breast muscle was high, resulting in a rapid decrease in pH value. Casein zymography showed that μ-calpain activity decreased rapidly in the early postmortem, but no significant change was found in μ/m-calpain activity during postmortem storage (P > 0.05). It was demonstrated that high temperature accelerated the activation and autolysis of calpain. Results of western blot also showed that desmin content significantly decreased during postmortem storage (P < 0.05). The MFI increased and shear force decreased during postmortem storage. Therefore, the μ-calpain in turkey breast muscle might be responsible the postmortem proteolysis and tenderization of turkey breast muscle.
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