Key Laboratory of Meat Processing and Quality Control, Ministry of Education, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.
Poult Sci. 2012 Jan;91(1):150-60. doi: 10.3382/ps.2011-01484.
The objective of this study was to investigate the contribution of the changes in the actin-myosin interaction and proteolysis on meat tenderization during postmortem storage. Following slaughter, chicken breast muscles were removed and stored at 4°C. Changes in the actin-myosin interaction over 48 h of aging were determined by monitoring the Mg(2+)- and Ca(2+)-ATPase activities. Shear force values, pH, protein degradation, calpain activities, and myofibrillar ultrastructures were also investigated. Results showed that the initial weak actin-myosin interaction strengthened at 12 h postmortem followed by a gradual weakening, which was supported by a decrease in Mg(2+)-ATPase activities and a lengthening of the sarcomeres. According to SDS-PAGE and Western blotting analyses, the 30-kDa troponin-T fragment could not be readily detected until 12 h, whereas, at the same time, desmin had been rapidly degraded. However, there was a gradual decline in μ-calpain activity, commencing after about 6 h. Meanwhile, the largest decline in shear force was observed between 12 and 24 h postmortem. These findings suggest that weakening of the strong actin-myosin interaction formed at rigor may play a large role in meat tenderization during the early period of storage. It is proposed that weakening of the actin-myosin interaction results in lengthening of the sarcomeres, and then activated calpains are more able to reach their targeted sites, enabling proteolysis. These 2 factors may be involved in the conversion of muscle to tender meat during postmortem storage.
本研究旨在探讨死后贮藏过程中肌动球蛋白相互作用和蛋白水解变化对肉嫩度的贡献。宰后，取出鸡胸肉并在 4°C 下贮藏。通过监测 Mg(2+)-和 Ca(2+)-ATP 酶活性来测定 48 小时老化过程中肌动球蛋白相互作用的变化。还研究了剪切力值、pH 值、蛋白质降解、钙蛋白酶活性和肌原纤维超微结构。结果表明，初始弱的肌动球蛋白相互作用在死后 12 小时增强，随后逐渐减弱，这与 Mg(2+)-ATP 酶活性降低和肌节拉长有关。根据 SDS-PAGE 和 Western blot 分析，直到 12 小时才可以检测到 30kDa 肌钙蛋白-T 片段，而此时肌联蛋白已迅速降解。然而，μ-钙蛋白酶活性逐渐下降，约在 6 小时后开始。同时，在死后 12 至 24 小时之间观察到最大的剪切力下降。这些发现表明，在僵硬时形成的强肌动球蛋白相互作用的减弱可能在贮藏早期对肉嫩度起重要作用。有人提出，肌动球蛋白相互作用的减弱导致肌节拉长，然后激活的钙蛋白酶更能够到达其靶向部位，从而实现蛋白水解。这两个因素可能参与了死后贮藏过程中肌肉向嫩肉的转化。
