Study on enzymatic browning and blanching methods of chestnut

The activity and thermal stability of polyphenol oxidase(PPO) in frozed chestnut were studied. The blanching methods and their effects on candying processing of chestnut were also investigated. Results showed that the thermal stability of PPO was higher than POD,the optimum temperature and pH of PPO were 20℃,6.5 respectively. When the relative activity of PPO was decreased to less than 8%,the enzymes causing browning in chestnut were estimated to be inactivated enough. Compared with the way of hot water and steam blanching,enzymatic browning in chestnut was inhibited efficiently by microwave blanching,and the sugar impregnation into chestnut was enhanced too in the processing of low-sugar candied chestnut. The optimal treatment of microwave blanching was that chestnut was heated at 4W/g power indensity for 6min.