Examination of antioxidant activity

The MAAs had antioxidant activity in addition to UV-protection. Heat-treated MAAs lost their UV-protective activity, but we examined whether they had antioxidant activity (Table 1). The results showed that the antioxidant activity increased after heat treatment compared to before treatment. In particular, the antioxidant activity of MAAs was weaker on the acidic side compared to ascorbic acid, but after heat treatment, MAAs showed antioxidant activity comparable to ascorbic acid over a wide range of pH.