Abstract: The acetone powder of ppo in lotus root being extracted from ice?.cold acetone,the effects of pH,temperature,concentration of substrate,and inhibitors on ppo's activity were investigated by using the spectrophotometric method.The results showed that the optimal pH and tempearture were 7.0 and  35 ℃,Km and Vm of ppo with catechol substrate were 22.7 mmol/L and 0.625 OD/min respectively,the extinct condition of ppo was 25 s at 100 ℃,sodium sulfite and ascorbic acid were strong inhiitors,with the effective concentration  being 3.00×10^-4 and 1.75×10^-4 respectively.

Key words: lotus root, polyphenol oxidase, browning, inhibitors