Effects of polyphenol content, polyphenol oxidase activity and pH on blackspot bruise of Japanese potato varieties

The polyphenol content, polyphenol oxidase (PPO) activity and pH of Norin No. 1 and Toyoshiro potatoes, representative processing potato varieties in Japan, were measured, and their effects on blackspot bruise were evaluated using multiple regression analysis. The analysis showed that among these biochemical factors, PPO activity most predominantly affects blackspot bruise. This result is useful for developing new blackspot-bruise-resistant varieties.