Fading of Anthocyanin Color by Ascorbic Acid and Anti-Fading Effect of Reducing Agents

Abstract

　We investigated the color fading of various anthocyanins in some fruits like passion fruits, strawberry and grape due to ascorbic acid and dehydroascorbic acid. The red color of anthocyanin fades with an increasing concentration of ascorbic acid or dehydroascorbic acid. Furthermore, short-term heat treatment (80℃, 5min) and medium-temperature long-term storage (20℃, 14d) promote the fading of anthocyanin color. The addition of reducing agents such as cysteine and glutathione or antioxidants like ferulic acid suppresses the discoloration of anthocyanins in the presence of ascorbic acid. In contrast, the coexistence of dehydroascorbic acid and reducing agents with anthocyanin promotes the discoloration of anthocyanin. These results were consistent in some anthocyanins in the fruits. Since reduced ascorbic acid is mainly present in fresh foods such as fruits, adding a reducing agent such as cysteine is effective in suppressing the color fading of anthocyanins due to ascorbic acid in processed fruit products.