The relation of polyphenols and polyphenol oxidase to the food quality of banana bud.

Abstract

Polyphenols (total phenol, flavanan tannin, vanillin-positive phenol, ethyl acetate-soluble phenol) and polyphenol oxidase (PPO) were characterized in banana buds of both edible and non-edible cv.; banana fruits at the mature green stage were used for comparison. The 3 parts of the bud (male flower, peduncle, bract) were used for analysis. For fruits, the peel and pulp were assayed individually. In the bud of cv. Saba (edible), the male flower contained the highest amount of polyphenols, and the main component was flavanan tannin (condensed tannin); small amounts of dopamine, dopa and catechin were detected. Male flowers of the buds of cv. Bungulan, Lacatan and Latundan contained more total phenol and vanillin-positive phenol than those of cv. Saba. In cv. Saba buds, the male flower also contained the highest PPO activity. NaCl (0.13M) inhibited PPO activity, but degree of inhibition varied among bud parts. PPO activity in fruit peel was 10x that in fruit pulp, but 9-26x less than that in bud parts. Male flowers from buds of other cv. contained less PPO activity than did cv. Saba buds, but fruits of other cv. showed similar activity to cv. Saba fruits. The Ki value for NaCl of PPO in cv. Saba peel was estimated as 0.28M (equivalent to 1.64% NaCl). Applying this to PPO in the bud, activity may be inhibited by 80-85% by NaCl concn. used for cooking buds in the home. Effects of steaming and NaCl addition on the taste of banana buds were studied. In buds of cv. Saba, but not the other cv., astringency and bitterness disappeared after steaming for 20 min and were decreased by NaCl. Addition of NaCl during cooking gave an attractive colour. The relationships of polyphenols and PPO to the food quality of banana buds are discussed.