山药中多酚氧化酶的活性测定及其护色研究

Measurement of PPO Activity and the Prevention of Discoloration of Yam

研究了山药中多酚氧化酶(PPO)的最适pH值、最适温度,设计了不同护色方案,以确立山药的最佳护色条件。采用分光光度法研究pH值、温度对酶活性的影响;比较不同护色液对酶活力的影响;将山药经不同护色条件护色后,低温烘干,粉碎过筛得山药粉,用分光光度法测定其甲醇-水溶液(1∶1)的吸光度。结果表明,以邻苯二酚为底物,山药PPO的最适pH值为5.6,最适温度为35℃,山药的最佳护色条件为:以0.25%的Na2SO3为抗氧化剂,并配以0.25%的柠檬酸和1.5%的NaCl为护色液。

To obtain the best condition for discoloration prevention of yam, the optimum pH and temperature of yam PPO (polyphenol oxidase) activity were determined. Different methods of prevention of discoloration were also inversigated. The effect of pH and temperature on PPO activity were studied and the effects of different of discoloration preverting solution on PPO activity were compared. Yam powder was obtained after crushing, qriddling and drying at low temperature using different discoloration-preventing processes. The yam powder were dissolved in the solution of methanol-water(1∶1). The absorbency of the solution was determined with spectrophotometer. The results showed that the optimum pH and temperature of yam PPO were 5.6 and 35℃ respectively. It was seen that the best condition prevention of discoloration of yam were, sodium sulfite 0.25%, citric acid 0.25% and the sodium chloride 1.5%.