Yin Y, Zhang W G, Zhou G H, Guo B
Key Laboratory of Meat Processing and Quality Control, Ministry of Education, Synergetic Innovation Center of Food Safety and Nutrition, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.
Key Laboratory of Meat Processing and Quality Control, Ministry of Education, Synergetic Innovation Center of Food Safety and Nutrition, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
J Anim Sci. 2014 Aug;92(8):3745-52. doi: 10.2527/jas.2014-7850. Epub 2014 Jul 1.
The objective of this study was to investigate the differences in protein modifications between pale, soft, and exudative (PSE) and red, firm, and nonexudative (RFN) pork during postmortem (PM) aging. Longissimus dorsi (LD) including 8 PSE and 8 RFN muscles were individually removed from 16 carcasses. These 16 LD muscles were vacuum packaged at 24 h after slaughter and stored at 4°C for 1, 3, and 5 d. The centrifugation loss, drip loss, color, protein solubility, protein oxidation, protein degradation including desmin, troponin T, and integrin, and μ-calpain activation were determined. The pH of PSE samples was significantly lower than that of RFN samples at both 1 and 24 h PM (P < 0.05). The L* values of PSE pork were significantly greater than that of RFN pork at different time point during PM storage (P < 0.01). The centrifugation loss of PSE samples at d 1 was extremely greater than samples from RFN pork (P < 0.01). The cumulative drip loss for d 0 to 1, d 0 to 3, and d 0 to 5 in PSE pork were significantly greater than that from RFN pork (P < 0.05). The carbonyl content of myofibrillar proteins was not significantly different between PSE and RFN pork samples (P > 0.05). In addition, PSE pork presented a lower solubility of sarcoplasmic protein, myofibrillar protein, and total protein than RFN pork except the solubility of myofibrillar protein at d 1 (P < 0.05). The intensity of intact desmin and troponin T 2 in PSE pork at d 3 and 5 were significantly greater than that in RFN pork (P < 0.05), whereas no significant difference was detected at d 1. The intensity of intact troponin T 1 in PSE pork at d 5 was greater than that in RFN pork (P < 0.05). However, more degradation products of integrin were detected in PSE pork compared to that of RFN pork at d 1 (P < 0.05). Red, firm, and nonexudative pork presented lower intensity of intact 80 kDa calpain and greater intensity of autolyzed 76 kDa product compared to PSE pork (P < 0.01). The results indicate that the degree of μ-calpain activation, the extent of protein degradation including desmin and integrin, and the level of protein solubility in PSE pork could contribute to its low water holding capacity during PM storage.
本研究的目的是调查宰后（PM）成熟过程中苍白、柔软、渗水（PSE）猪肉和红色、坚实、不渗水（RFN）猪肉之间蛋白质修饰的差异。从16头猪胴体上分别取下包含8块PSE肌肉和8块RFN肌肉的背最长肌（LD）。这16块LD肌肉在屠宰后24小时进行真空包装，并在4°C下储存1、3和5天。测定离心损失、滴水损失、颜色、蛋白质溶解度、蛋白质氧化、包括结蛋白、肌钙蛋白T和整联蛋白在内的蛋白质降解以及μ-钙蛋白酶激活情况。在宰后1小时和24小时，PSE样品的pH值均显著低于RFN样品（P<0.05）。在PM储存的不同时间点，PSE猪肉的L*值显著高于RFN猪肉（P<0.01）。第1天时PSE样品的离心损失极显著高于RFN猪肉样品（P<0.01）。PSE猪肉在第0至1天、第0至3天和第0至5天的累计滴水损失显著高于RFN猪肉（P<0.05）。PSE和RFN猪肉样品之间肌原纤维蛋白的羰基含量没有显著差异（P>0.05）。此外，除第1天肌原纤维蛋白的溶解度外，PSE猪肉的肌浆蛋白、肌原纤维蛋白和总蛋白的溶解度均低于RFN猪肉（P<0.05）。第3天和第5天时，PSE猪肉中完整结蛋白和肌钙蛋白T2的强度显著高于RFN猪肉（P<0.05），而在第1天时未检测到显著差异。第5天时，PSE猪肉中完整肌钙蛋白T1的强度高于RFN猪肉（P<0.05）。然而，与RFN猪肉相比，在第1天时PSE猪肉中检测到更多的整联蛋白降解产物（P<0.05）。与PSE猪肉相比，红色、坚实、不渗水猪肉呈现出较低强度的完整80 kDa钙蛋白酶和较高强度的自溶76 kDa产物（P<0.01）。结果表明，PSE猪肉中μ-钙蛋白酶的激活程度、包括结蛋白和整联蛋白在内的蛋白质降解程度以及蛋白质溶解度水平可能导致其在PM储存期间的低持水能力。
