RELATIONSHIP BETWEEN APPLE RIPENING AND BROWNING - CHANGES IN POLYPHENOL CONTENT AND POLYPHENOL OXIDASE

Changes in the browning of apple juice, polyphenol content, and polyphenol oxidase were examined during apple ripening. The degree of browning of apple juice, the phenol content per gram of flesh, and the polyphenol oxidase (PPO) activity per milligram of protein decreased during ripening. From 4.5 to 6 months after flowering, the amount of PPO per milligram of protein, determined by an enzyme-linked immunosorbent assay, was constant, but its specific activity decreased, suggesting that PPO had denatured. PPO was uniformly distributed in the immature and mature apple, but active PPO was mainly localized around the core in the mature apple.