摘要:
为了研究羊肉宰后成熟过程中极限pH对肌原纤维蛋白特型即肌联蛋白、伴肌动蛋白、肌间线蛋白和肌钙蛋白-T降解及肌原纤维小片化指数的影响。本文选取50只羊的右侧背最长肌,贮存于4 ℃条件下,在宰后时间点分别为1 h、1、2、3、5 d和7 d时,测定其pH。按照宰后2 d的pH将肉样分成三组:高极限pH组(5.72±0.03),中极限pH组(5.54±0.01)和低极限pH组(5.40±0.02)。在每个宰后时间点,测定肌联蛋白、伴肌动蛋白、肌间线蛋白、肌钙蛋白-T降解程度和肌原纤维小片化指数(MFI)。结果表明:肌联蛋白在高极限pH组中宰后1 d开始降解;在宰后1 d时,高极限pH组肌间线蛋白相对灰度值显著低于中极限pH组和低极限pH组(p<0.05);肌钙蛋白-T在高极限pH组中,宰后1 d已出现降解条带。而伴肌动蛋白在中极限pH组中降解较快,在宰后1 d开始降解。另外在宰后1、2、3、5、7 d时,高极限pH组和中极限pH组的肌原纤维小片化指数显著高于低极限pH组的肌原纤维小片化指数(p<0.05)。极限pH通过影响这些肌原纤维蛋白降解来促进宰后肌肉成熟过程并且肌联蛋白、肌间线蛋白和肌钙蛋白-T的降解,加快了宰后前期嫩化过程。这为揭示宰后肉嫩度形成机理提供理论基础。
Abstract:
This study was aimed to investigate effects of muscle ultimate pH (pHu) on titin, nebulin, desmin, troponin-T degradation and myofibril fragmentation index (MFI) in ovine muscle. After 50 animals were slaughtered, the right longissimus lumborum (LL) muscles were stored at 4℃ for 7 d. Based on muscle the pH at post-mortem 2 d, muscles were classified into three groups:the high pHu (5.72±0.03), intermediate pHu (5.54±0.01) and low pHu (5.40±0.02) muscles. Muscle pH, MFI and degradation of titin, nebulin, desmin and troponin-T were measured at 1 h, 1, 2, 3, 5 and 7 days postmortem. The data obtained showed that titin started to the degradation in the high pHu muscles on day 1 postmortem. On day 1 postmortem, the intensity of desmin was lowest in the high pHu muscles than that that in intermediate and low pHu (p<0.05). Degradation of troponin-T occurred on day 1 postmortem in the high pHu muscles. But degradation of nebulin was observed on day 1 postmortem in the intermediate pHu muscles. At the same time, meat in high and intermediate pHu groups had higher MFI than that in low pHu group at 1, 2, 3, 5 and 7 days postmortem (p<0.05). The study showed that muscle ultimate pH influenced the degradation of these myofibrillar proteins postmortem and thus meat tenderization. Degradation of titin, desmin and troponin-T improved directly meat tenderness in early stage of ageing. This provided a theoretical basis for mechanisms involved in tenderization of meat.
百度学术
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