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Reaction kinetics of the acetaldehyde-mediated condensation between (−)-epicatechin and anthocyanins and their effects on the color in model wine solutions

Liu, Yue, Zhang, Xin-Ke, Shi, Ying, Duan, Chang-Qing, He, Fei
Food chemistry 2019 v.283 pp. 315-323
acetaldehyde, activation energy, anthocyanins, color, endothermy, hydroxylation, isomers, methylation, models, reaction kinetics, temperature, wines
The reaction kinetics of five primary wine anthocyanins (cyanidin-3-O-glucoside, peonidin-3-O-glucoside, delphinidin-3-O-glucoside, petunidin-3-O-glucoside, and malvidin-3-O-glucoside) and (−)-epicatechin with the presence of acetaldehyde were evaluated in model wine solutions at a range of varying temperatures (25, 35, 45, and 55 °C). The loss of anthocyanins followed first-order reaction model, while the formation of two isomers of anthocyanin ethyl-linked (−)-epicatechin was fitted to zero-order reaction model. The rate constant (k) showed that petunidin-3-O-glucoside was the most reactive anthocyanin, followed by the two 3′,4′-substituted anthocyanins (peonidin-3-O-glucoside and cyanidin-3-O-glucoside), while the least reactive were another two 3′,4′,5′-substituted anthocyanins (malvidin-3-O-glucoside and delphindin-3-O-glucoside). The activation energies (Ea) indicated that the formation of ethyl-linked products from methylated anthocyanins were more sensitive to temperature than that from hydroxylated anthocyanins. Thermodynamic parameters showed a non-spontaneous and endothermic process. Besides, the evolution of the visible color of reaction solution was affected by the stability of anthocyanins and the formation of ethyl-linked products.