Comparison of Enzymatic Browning of Japanese Pear and Apple

Abstract

When Japanese pear and apple are cut, the section of Japanese pear does not turn brown as readily as apple, although both fruits belong to the same family. Here, the enzymatic browning of the two fruits is compared. The activity of polyphenol oxidase (PPO) of Japanese pear was higher than that of apple. The PPO of Japanese pear existed uniformly throughout the fruit, while the PPO of apple was localized around the core. The content of chlorogenic acid, (+)-catechin, and (-)-epicatechin in Japanese pear was much lower than in apple. When these polyphenols were added to Japanese pear juice, the juice turned as strong a brown color as apple juice. Therefore, the reason why Japanese pear does not turn brown as easily as apple is that the amount of substrate of PPO in the former is much less.