Shuo Feng^{1, 2}, Shan W^{1, 2}, Michiyuki Kojima^1,

The effects of protease treatment, glucose addition and adzuki beans saccharification on the radical-scavenging properties of soymilk were evaluated. It was found that protease treatment (8.9 U/ml) and the glucose addition (84 mg/ml) increased the radical-scavenging capacity of soymilk by 1.8 folds. Adzuki bean saccharification (51 U/ml α-amylase and 6.25 U/ml amyloglucosidase) and protease treatment (8.9 U protease/ml) increased radical-scavenging activity by 2.3 folds. This effect was not solely due to the presence of adzuki polyphenols, as melanoidin production, but also due to increased radical-scavenging activity. The correlation between the radical-scavenging capacity of soymilk and melanoidins, or that of mix bean milk and melanoidins was high (soymilk: R² = 0.94; mix bean: R² = 0.96). Collectively, these data indicated that protease treatment, glucose addition and adzuki bean milk saccharification affect the radical-scavenging activity of soymilk through melanoidin production. These findings should contribute to the development of soymilk-based antioxidant-rich functional foods formulation in the future.

soymilk, functional food, radical-scavenging activity, antioxidant activity, proteolytic treatment, saccharification, maillard reaction; melanoidins