宰后猪PSE肉特征形成与初期温度的关系

Relationship between Development of Porcine PSE Characteristics and Initial Postmortem Temperature

摘要:

研究了“发白、质地柔软和出水”（PSE）猪肉特征的形成与宰后初期温度关系，取宰后20 min猪背最长肌分别经过0，20，40 ℃孵育处理至宰后2 h，然后放置于4 ℃进行成熟。其中分别取宰后20 min、1 h、2 h、24 h肉样并立即于液氮冷冻然后放置-40 ℃冰箱保存以待测定生化指标，另外测定宰后24 h新鲜肉样的肌肉品质和蛋白质特征聚丙烯酰胺凝胶电泳（SDS-PAGE）分析。结果显示：宰后初期40 ℃处理组肉样R值升高速度，乳酸的积累速度和pH下降速度均较快，表明了高温导致了快速的糖酵解，另外不同温度间肌浆蛋白SDS-PAGE图谱存在差异，高温组100 ku和35 ku的条带表达量较少，表明部分肌浆蛋白可能发生变性，最终导致高温处理组肌肉颜色亮度值显著较高以及较高的蒸煮损失。以上结果表明高温处理可以导致发白、质地柔软和出水等特征肉的产生，而快速的糖酵解可能是主要的原因。

Abstract:

Pork longissimus muscle were taken at 20 min postmortem, kept at 0, 20 and 40 ℃ until 2 h postmortem and then stored at 4 ℃, respectively. 20 min, 1 h, 2 h and 24 h postmortem pork samples were selected and rapidly frozen in liquid nitrogen, and stored at -40 ℃ before analyzed. During incubation, rapid increase of R value, accumulation of lactic acid and decrease of pH value were found in the high temperature group (40 ℃).These data indicated that glycolysis could be activated much more in the high temperature group (40 ℃). When analyzing the extracted proteins with SDS-PAGE, it revealed that both 100 ku and 35 ku polypeptides from sarcoplasmas faction was associated with the myofibrillar fraction. Moreover, the 40 ℃ group had higher L * values and cooking loss compared with the other two groups. These result indicated that high initial postmortem temperature could resulted in pale and exudative characteristics in pork, partly because the glycolysis was activated at high temperature.