Characterization of Polyphenol Oxidase in Peaches Grown in the Southeast1

A crude polyphenol oxidase (PPO) preparation extracted from ‘Redhaven’ peaches ( Prunus persica (L.) Batsch) showed only catecholase but not cresolase enzyme activity. The PPO activity increased sharply near the end of maturation. A shift from a single pH optimum at 6.2 to dual optima at pH 6.0 and 6.5 during maturation possibly indicates synthesis of new isozymes. The temperature optimum for peach PPO was near 37°C and the Michaelis constant was 2.9 × l0 -2 M when catechol was used as substrate. The peach PPO remained very active even at 3°.