The degradation of anthocyanin at mature stage can be
explained in many different ways.
report that hydrogen peroxide (H2O2) formed by oxidation of
ascorbic acid in the presence of oxygen and copper ions cause discoloration
of anthocyanins.
The anthocyanins can also be degraded
by the endogenous enzymes present in tissues of plants, such as
glycosidases, polyphenol oxidases and peroxidases.
The degradation can be further explained by the occurrence of the condensation
reaction between ascorbic acid and anthocyanin, forming
unstable products that degrade into colorless compounds