Abstract

• An enzyme called polyphenol oxidase (1.10.3.1) is responsible for the browning events that occur when handling damage to the cells. Peels from bananas were gathered in the Thiri Mingalar market in the Yangon Region. Using ammonium sulphate precipitation (20-80 %), dialysis, and gel filtration chromatography on Sephadex G-100, the enzyme polyphenol oxidase (PPO) was extracted from banana peels. Using catechol as a substrate at 420 nm, the spectrophotometric technique was used to assess the polyphenol oxidase activity. The modified Lowry's method was used to determine the protein content using a standard of bovine serum albumin (BSA) at 550 nm. The purification of polyphenol oxidase over crude extract was 3.52 folds, and 0.18 % of the protein was obtained. pH 7.0 and 30 °C were found to be the optimum conditions. It was shown that after 5h of incubation at pH 7.0, polyphenol oxidase activity remained at approximately 68.6 %. A particular pH of 7.0 was used to study the heat sensitivity of polyphenol oxidase at various temperatures of 25, 30, and 35 °C for various incubation periods (0, 1, 3, and 5 h). At 30, 25, and 35 °C, polyphenol oxidase activity was shown to be relatively stable; after 5 h of incubation, it retained 67.8, 49.6, and 26.9 % of its original activity, respectively. The activation energy (Ea) of the polyphenol oxidase-catalyzed reaction was determined to be 2.404 kcal mol-1 .