Influence of copigmentation on stability of anthocyanins from purple potato peel in both liquid state and solid state.

Copigmentation is an important way to improve the stability of anthocyanins. The effect of the copigmentation on the stability of the anthocyanin from the purple potato peel (PA) was evaluated from the view of the kinetics and thermodynamics in both the liquid state and the solid state for the first time. In the liquid state, the copigmentation of the ascorbic acid decreased the stability of PA by the activation-energy evaluation, while that of the citric-acid monohydrate and glucose increased the stability of PA. Moreover, the stability of the copigmented PA presented the positive correlation with its ratio to the ascorbic acid and citric-acid monohydrate individually. The copigmentation of the glucose at the different ratio did not affect the stability of PA significantly. In the solid state, the stability of PA was improved by the copigmentation with the ascorbic acid, citric-acid monohydrate, and glucose by the transition-temperature evaluation. Moreover, the stability of the copigmented PA showed the negative correlation with its ratio to the ascorbic acid, citric-acid monohydrate, and glucose individually.