Protective effects and mechanism of amino acids as chokeberry cyanidin and its glycoside protectant under the condition of vitamin C coexistence.

In the presence of vitamin C, cyanidin and cyanidin glycosides are degraded during the processing and storage of food products. To solve this issue, we investigated the protective effects and mechanism of action of five amino acids on the stability of cyanidin and its glycosides from chokeberry. The results showed that 0.3% tryptophan most effectively inhibited the degradation of cyanidin and its glycosides in the presence of vitamin C, under ultraviolet, dark, and sucrose-rich conditions. Fluorescence spectrum analysis showed that tryptophan could form noncovalent binding complexes with cyanidin-3-O-galactoside and cyanidin through hydrophobic and electrostatic forces and hydrogen bonds. Molecular docking results showed that the indole structure of tryptophan could form hydrophobic interactions with cyanidin-3-O-galactoside and cyanidin via hydrogen bonding, resulting in greater protection. Therefore, tryptophan could effectively protect cyanidin and its glycosides in cyanidin- and cyanidin glycoside-rich food products.