Cape gooseberry (Physalis peruviana) is an exotic fruit highly valued, however it is a
very rich source of polyphenol oxidase (PPO). In this study, Cape gooseberry PPO was
isolated and biochemically characterized. The enzyme was extracted and purified using
acetone and aqueous two-phase systems. The data indicated that PPO had the highest
substrate affinity for chlorogenic acid, 4-methylcatechol and catechol. Chlorogenic acid
was the most suitable substrate (Km = 0.56 ± 0.07 mM and Vmax = 53.15 ± 2.03
UPPO.mL-1.min-1). The optimal pH values were 5.5 for catechol and 4-methylcatechol
and 5.0 for chlorogenic acid. Optimal temperatures were 40ºC for catechol, 25ºC for 4-
methylcatechol and 20ºC for chlorogenic acid. In inhibition tests, the most potent
inhibitor was found to be ascorbic acid followed by L-cysteine and quercetin. This
study shows possible treatments that can be implemented during the processing of Cape
gooseberry fruits to prevent browning.