Abstract: Polyphenol oxidase (PPO) is related to undesirable brown discoloration of wheat-based end products such as noodle and steamed bread. In total, 22 main cultivars sown in 11 locations in middle and lower Yangtze Valleys in 1999-00 season were used to investigate the effects of genotype, environment and other quality characteristics on flour PPO activity. The variability in flour PPO activities was influenced by growing location, genotype and their interaction significantly. Flour PPO activities were related to flour L*, with correlation coefficient -0.55. Grain hardness, flour b*, Zeleny sedimentation value, Farinograph water absorption and dough stability were significantly correlated with flour PPO activity, with r = 0.57, 0.69, 0.46, 0.42 and 0.46, respectively. Significant negative correlations were found between PPO activity and test weight and starch pasting character.

Key words: T.aestivum, Polyphenol oxidase, Brown discoloration, Processing quality