Influence of Apple Polyphenols on the Properties of Polyphenol Oxidase
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Abstract:
Influence of different apple polyphenols on the properties of polyphenol oxidase (PPO) was investigated and the suitable conditions of PPO enzymatic oxidation were obtained by employing chlorogenic acid, catechin, epicatechin and phlorizin as substrates and by determining the change of absorbance in the phosphate buffer model system. The results showed that the substrates had an important impact on the reactive characteristics of PPO. The optimum pH of enzymatic oxidation of chlorogenic acid, catechin, epicatechin and phlorizin by PPO were 5.0, 4.0, 4.5 and 4.5, respectively. The best temperature of enzymatic oxidation of the above-mentioned substrates were 55, 70, 60 and 50 ℃, respectively. And the polyphenol substrate concentration for the four substrates were 5, 0.5, 2 and 10 mM, respectively. Furthermore, appropriate increase of enzyme activity could promote the enzymatic browning reaction. The affinity of the four substrates for PPO was in the order of catechin ? epicatechin﹥chlorogenic acid ? phlorizin. This study will supply a basis for browning control of apple juice.
