冷藏南美白对虾丝氨酸蛋白酶活力与黑变相关性研究

为探明冷藏对虾黑变规律,研究了南美白对虾在为期10 d的冷藏过程中黑变与丝氨酸蛋白酶(serine protease,SP)的活性变化及其相关性。结果表明,南美白对虾感官黑变呈现出先慢后快的特征,前2 d基本无变化,第3 d时变化开始加快,第5 d变化最为显著,第6至第10 d黑变速率差异不显著,第4 d是黑变防控的关键期。进一步定量分析表明对虾不同部位的黑变速率存在显著差异,冷藏至第4 d时头部、腹部和尾部间的明度L值差异开始明显,第5 d时三者之间达到显著性差异(P0.05);统计分析表明对虾冷藏过程中不同部位SP活力与黑变存在显著相关性,头部组织对对SP活力变化最为敏感,其斜率k为0.0312,明显大于尾部的0.0271和腹部的0.0128,是黑变调控的关键部位。本研究证明在冷藏南美白对虾体内也存在酚氧化酶激活系统,SP活力水平同样对酚氧化酶原的激活水平起重要调控作用,其规律和机制有待深入研究。

The Melanosis, Serine Protease Activity and Their Correlation of Litopenaeus vannamei during Cold Storage

To ascertain the melanosis rule of shrimp during cold storage, the melanosis, serine protease activity and their correlation in Litopenaeus vannamei during 10-day cold storage were investigated. The results showed that the melanosis speed of the shrimp was slow at first and then accelerated, which had no obvious change in appearance until the third day and the most distinct melanosis process was found at the fifth day. This indicated that the fourth day was the key term for melanosis inhibition. Quantitative analysis revealed that there was significant difference in melanosis score among different parts of Litopenaeus vannamei, in which the difference of brightness value L between cephalosome, abdomen and stern became evident at the fourth day and was significant at the fifth day (P<0.05). The correlations of melanosis and serine activity between the three parts were statistically analyzed and appeared that cephalosome was the crucial part for melanosis inhibition due to its most sensitive property to serine protease activity, with slop of k between brightness and serine protease activity of 0.0312, which was larger than that of abdomen (0.0271) and stern (0.0128). This study demonstrated that the prophenoloxidase activating system was discovered in cold storage shrimp, and the level of serine protease activity had similar regulatory effect on the status of prophenoloxidase activating system but its pattern and mechanism remained further study.