摘要：The browning of fruits can be considered as an enzymatic oxidation which is believed to be one of the main causes of quality loss during post-harvest handling. The enzymes responsible for this are the oxidoreductases; the polyphenol oxidase (PPO) (monophenol, o-diphenol, oxygen oxidoreductase; EC 1.14.18.1) belongs to this group. This enzyme, which is found in the sapodilla plum (Achras sapota), was purified using a phenylsepharose and a SephacrylS-200 columns. The molecular weight of the purified enzyme was estimated to be about 66 kDa by gel filtration and 29 kDa by SDS-PAGE. A single protein band was found using the latter system (SDS-PAGE), which shows that the PPO of the pulp of the sapodilla plum may be composed of two protein subunits with similar molecular weight. The optimum pH was 7.0 and the optimum temperature 60℃. The most effective inhibitors tested were ascorbic acid, sodium metabisulfite and acetic acid.
关键词：Enzymatic System; Oxidation; Polyphenol Oxidase; Browning Process; Nutritional Value
