Studies On The Characterization Of Peroxidase And Changes Of Peroxidase Activity From Carambola Fruit

Carambola(Averrhoa carambola Linn) is one of many important fruits in southern China, and it has extremely rich nutritional value and pharmacological value. But, enzymatic browing occurs easily in the fruit preservation, processing and storage, which led to the loss of the commodities quality and appearance easily. Polyphenol oxidase(PPO) and peroxidase(POD) are main enzymes which induce enzymatic browning of many fruits. At present, the PPO from Carambola and enzymatic browning which was caused by it have been researched. But, the research on the carambola fruit POD has fewly reported. In view of controlling the enzymatic browning of carambola fruit, the study that is the purification characterization research of POD from carambola fruit, and the changes of peroxidase activity in different varieties of carambola will be carried out and provide a theoretical basis.The main findings were as follows:1. The experiment explored the impact of the homogenate extraction and acetone extraction on the extraction efficiency of carambola fruit POD. The optimum extraction conditions for acetone extraction were90%for the concentration of acetone,30min of the extraction time, solid to liquid ratio of1:4. The results showed that the effect of acetone extraction method was better. The acetone extraction which has been applied could obtain the enzyme with higher specific activity, and the purity of the enzyme was higher, and it were conducive to the further purification of enzyme solution.2. The enzyme activity of POD crude enzyme extracted from carambola fruit after DEAE-Toyopearl650M, Butyl-Toyopearl650M, DEAE-sephadexA-50significantly increased, and the purification factor and recovery rate of the carambola fruit were11.68times and10.9%through chromatographies.3. The purified enzyme can rapidly catalyze guaiacol.The Km value was11.47mmol/L. The optimum pH value of carambola POD was at6.5, and the optimum temperature of enzyme was at35℃. The thermal stability range of POD was30-60℃,the pH range of stability from carambola POD was alao wider,which was relatively stable in range of pH6.0-11.0. best inhabitor of the enzyme activity was the ascorbic acid, followed by hydrochloride-L-cysteinc. In the fruit processing and storage, these two compounds can be betterly used for controlling the enzymatic browning of carambola fruit4. The activity variation of the carambola fruit during storage as follows:it was found that the trend of POD activity from Malaysia3carambola fruit during storage was reduced, and then increased, and lowered finally; the POD activity from Malaysia1carambola fruit and Singapore red carambola showed a trend which was increased, and then decreased during carambola fruit storage. The POD activity was lowered after Bagging, low temperature storage and chitosan coating on peroxidase in the postharvest Carambola Fruits.