Characterization of 'Biuti' Peach Polyphenoloxidase

Abstract

In Brazil canned 'Biuti' peach is a very popular form of this sub-tropical fruit. This production represents an important economic agro-activity in Minas Gerais, Brazil during the summer period, in preparation for the Christmas celebrations. The aim of this work was to characterize the 'Biuti' peach polyphenoloxidase (PPO), since peach products show enzymatic oxidation of the polyphenols by oxidative enzymes, which affects the products during their shelf life. Two different hypothesis for the browning problem in processed peaches were studied: the inadequacy of the blanching treatment and the presence of a latent phenolase in the peaches. The PPO was characterized: pH optimum (5.5) and stability (5.5-6.5); optimum temperature at 20 degrees C and 80% of the activity retained after 30 min at 15-40 degrees C. The test for the presence of latent PPO in the processed and canned peaches was negative. Ascorbic acid, beta-mercaptoethanol, sodium metabisulfite, and cysteine were efficient in inhibiting the PPO.