Abstract:

The enzymatic properties of polyphenol oxidase (PPO) extracted from Stachys floridana Schuttl.ex Benth were characterized. Meanwhile, the inactivation of this enzyme by thermal treatment or adding chemical inhibitors was investigated, and a compound inhibitor composed of three selected chemical inhibitors (citric acid, vitamin C and L-cysteine) was developed and its formulation was optimized. The optimal reaction pH, time and temperature conditions for PPO activity were 5.0, 2.0 min and 30 ℃, respectively. Color preserving agents such as ascorbic acid, L-cystenine, citric acid, NaHSO3, Na2SO3 had a significant inhibitory effect on PPO activity. The optimal combinatorial formula was composed of 0.05 g/100mL citric acid, 0.05 g/100mL vitamin C and 0.05 g/100mL L-cysteine, and the resultant enzyme inhibition rate reached up to 93.5%.

Key words: Stachys floridana Schuttl.ex Benth, polyphenol oxidase, PPO activity, inhibition rate, control