凡纳滨对虾PPO的组织分布和活性与其贮藏过程中黑变的关系

Relation of Tissue Distribution and Activity of Polyphenol Oxidase from Litopenaeus vannamei and its Melanosis during Storage

研究了凡纳滨对虾多酚氧化酶（PolyphenolOxidase，PPO）在其组织中的分布和活性、PPO的最适pH值和稳定性，分析了不同包装方式（真空包装与非真空包装）和不同贮藏温度（．18℃、4℃、25℃）对虾黑变和PPO活性的变化规律，探讨了对虾黑变与PPO催化反应速度和贮藏温度的关系以及PPO酶活与贮藏温度的关系。结果表明：凡纳滨对虾的虾壳和虾头部位的PPO含量和活性较高，虾肉与虾足中PPO含量和活性较低；对虾PPO的最适pH值为6，在pH值扣8之间具有较好的稳定性和较高的活性；对虾黑变与贮藏温度和PPO催化反应速度呈正相关，PPO相对酶活与贮藏温度呈负相关；真空包装隔绝氧气和低温抑制PPO活性，降低了PPO的催化反应速度，从而减缓了对虾的黑变。研究结果为凡纳滨对虾在贮藏和加工过程中防止和控制黑变提供理论参考。

The optimal pH, stability, tissue distribution and activity of polyphenol oxidase （PPO） from Litopenaeus vanname were studied. The effects of different packages （vacuum and non-vacuum package） and different storage temperatures （-18 ℃, 4 ℃, 25 ℃） on the melanosis and PPO activity ofLitopenaeus vanname were analyzed. Meanwhile, the relationship of melanosis with PPO catalytic reaction rate and storage temperature and the relationship between PPO activity and storage temperature were discussed. The results showed that the activity of PPO from the shell and head of Litopenaeus vanname was higher, while it was lower in the abdomen muscle and pleopods. The optimal pH of PPO was 6.0 and it was more stable with higher activity at pH 6.0-8.0. The melanosis was positively correlated with storage temperature and catalytic reaction rate of PPO; the relative activity of PPO was negatively related to storage temperature; vacuum package effectively isolated Litopenaeus vanname from oxygen and lower temperature inhibited PPO activity, thus PPO catalytic reaction rate was decreased and the melanosis was prevented. It will provide a theoretical reference for controlling the melanosis of Litopenaeus vannamei during storage and processing.