Abstract
Changes of polyphenol oxidase (PPO, o-diphenol : oxygen oxidoreductase, EC. 1. 10.3. 1) activity of banana (Musa sapientum L.) fruits during ripening treatment with and without ethylene were determined. The total and soluble PPOs of pulp, which were extracted with and without detergent (Tween 80), were about 100 and 2 unit/g fresh weight, respectively. Both total and soluble pulp PPOs were remarkably increased and showed a maximun peak like a climacteric peak of respiration during the ethylene-ripening treatment. However, in the non-treated fruits, both total and soluble pulp PPOs changed a little during the treatment. In banana peel, total and soluble PPO were about 110 and 0.7 unit /g fresh weight, respectively. Both total and soluble PPO activities of peel were little affected by the ethylene-ripening treatment. These results suggested that the banana PPOs were mainly presented in pulp and peel as a “latent form”, and only “soluble pulp PPO” was affected by ethylene-ripening treatment.
