Copigmentation of Mahonia Bealei Anthocyanins by Tannin

Abstract

This study investigates the copigmentation effect and its underlying mechanism of tannin on Mahonia bealei anthocyanins (MBA). Results show that the addition of tannin increases the absorption and maximum absorption wavelength of MBA. At pH 3.73, the activation energy of MBA-tannin adduct is 2.43 times that of MBA. Under the same temperature, MBA-tannin complex shows better heat stability as exemplified by lower degradation rate and longer half-time. The light-induced degradation rate constant of MBA-tannin is 93.33% of that of MBA. It is shown in this paper that tannin can improve the heat and light stability of MBA and therefore is efficient as a copigment. Finally, the IR spectra suggest that the copigmentation effect is due to the formation of hydrogen bonds between tannin and MBA via associated hydroxyl groups.