Studies On The Copigmentation Between Wine Anthocyanins And Copigmentation And Their Influences In The Color Expresssion

Color is one of the important indicators for rganoleptic qualities of red wines.Monomeric anthocyanins are the main pigments in young red wine. Copigmentation betweenmonomeric anthocyanins and copigments has been reported as a safe and effective way toenhance and stabilize color intensity. But it is clear neither the magnitude of thecopigmentation between different copigments and monomeric anthocyanins nor how thestructures of copigments and monomeric anthocyanins influence copigmentation.This project systematically dicussed the correlations between monomeric anthocyaninsand color of different wine varieties by multivariate statistical analysis. It also studied thecopigmentation between eight copigments and anthocyanins and their influences in the colorexpression. The results not only had important theoretical values in improving the mechanismof pigments change, analyzing the effects of structures by anthocyanins and copigments butalso had positive applications in how to enhance red wine color intensity and stability.The main conclusions were listed as follows:(1) The relationship models between wine color and anthocyanin contents in CabernetSauvignon, Cabernet Gernischt and Merlot wines were firstly analyzed by both multiple linearregression (MLR) and partial least squares regression (PLSR) on the basis of totalquantification. MLR and PLSR both successfully predicted color from the monomericanthocyanin composition of the wine. The results verified each other and enhanced theirreliabilities. Delphinidin-3-glucoside (Dp3g), malvidin-3-O-acetylglucoside (Mv3ac), andDp3g had the greatest impact on wine color of Cabernet Sauvignon, Cabernet Gernischt andMerlot respectively.(2) Copigmentation reactions between three monomeric anthocyanins and eightcopigments (quercetin, quercitrin, epicatechin, epigallocatehin, caffeic acid, syringic acid,tannin VVR and VR-color) was investigated in model wine solutions. And the aim of researchwas to study the effects of copigmentation between different anthocyanins and copigments.The magnitudes of the copigmentation between different copigments and same anthocyaninwere different. Quercitrin and caffeic acid appeared as the effective copigments. The effect ofcopigmentation induced by quercetin was not stable, decreasing largely in the later storageperiod. Although the magnitude of copigmentation between VR-color and anthocyanins washigh, its high value in yellowness resulted in not being conducive to keep young red winecolor. The copigmentation effects induced by eight copigments on malvidin-3-O-glucoside(Mv3g) and Mv3ac were higher than on Dp3g. The differences of copigments andanthocyanins resulted in different capacities of maintaining the color. Quercitrin and caffeicacid helped to maintain the color of anthocyanin solutions during storage. And the degree ofmaintaining for Mv3g and Mv3ac solutions were higher than that for Dp3g.(3) In order to further explore the influences of specific structures on copigmantation,thermodynamic parameters of copigmentation involving three monomeric anthocyanins weredetermined in model wine solutions. The observed negative values of the Gibbs free energyindicated that copigmentation formation was spontaneous. And the negative enthalpy andentropy values clearly indicated that copigmentation was an exothermic reaction. A comparison of interactions for epicatechin and epigallocatechin may confirmed that hydroxyland planar molecule benefited copigmentation. The results of interactions for quercetin andquercitrin indicated that the degree of glycosylation of copigment inhibited anthocyanin fromaligning itself in an optimal spatial arrangement for copigmentation. However, the affinity andsystem stability of caffeic acid were higher than those of syringic acid. The structures ofanthocyanins also effected copigmentations greatly. Methylation favored copigmentation, butacetylation reduced the magnitude of copigmentation. The impact of methylation oncopigmentation was higher than that of acylation.