Reactions of Anthocyanins and Tannins in Model Solutions

Abstract

The reaction between procyanidin dimer Ec-EcG (B2 3'-O-gallate) and malvidin 3-O-glucoside (Mv3glc) was studied in a model solution system at two different pH values, 2.0 and 3.8. Disappearance of both species was much faster at pH 3.8 than at pH 2.0. That of Mv3glc was increased in the presence of Ec-EcG, whereas that of Ec-EcG was the same in the presence or absence of the anthocyanin. Values of absorbance at 520 nm measured at pH 2.0 were correlated with the amount of residual Mv3glc. Those measured at pH 3.8 hardly changed during the incubation, but absorbance values at 420 and 620 nm as well as resistance to sulfite bleaching were much increased, confirming that Mv3glc was converted to other pigments. Anthocyanin-flavanol adducts were observed at both pH values, but their structures were different. At pH 2.0, cleavage of the procyanidin linkage followed by nucleophilic addition of flavanol or anthocyanin moieties led to (Ec)(n)-EcG and (Ec)(n)-Mv3glc, respectively. At pH 3.8, nucleophilic addition of Ec-EcG onto the anthocyanin yielded Mv3glc-(Ec-EcG).

Polyphenols in foods are more complex than often thought

“…Such adducts were also obtained in wine-like model solutions containing anthocyanins and procyanidins. Their formation involves cleavage of the tannin interflavanic linkage, followed by nucleophilic addition of the anthocyanin hemiketal to the carbocation thus released and dehydration of the resulting adduct to the corresponding flavylium (32). The second group (Figure 3, right) consists of colorless adducts in which the anthocyanin and flavanol units are linked by both carbon-carbon (C4-C8) and ether (C2-O-C7) bonds (A-type), formed by nucleophilic addition of the flavanol to the anthocyanin flavylium cation (33).…”

Simultaneous separation and identification of oligomeric procyanidins and anthocyanin‐derived pigments in raw red wine by HPLC‐UV‐ESI‐MSn

“…5,6 Indeed, the MS/MS spectra for the corresponding [M] C ions (Fig. 4(C)) showed only a main fragment arising from the loss of the dehydrated-glucose moiety ( 162 Da).…”

“…Because of the large number of polyphenols in wine and the low levels of some of them, their analysis generally requires preliminary fractionation/purification steps 4,5,7,9 -11,13,14,16 -19 and/or studies in model artificial systems 6,12,15 prior to off-line high-performance liquid chromatography (HPLC). Standard procedures include enrichment techniques such as solid-phase extraction, 20,21 liquid-liquid extraction 22 and column chromatography fractionation.…”

Phenolic Compound Profiles in Grape Skins of Cabernet Sauvignon, Merlot, Syrah and Marselan Cultivated in the Shacheng Area (China)

“…They contribute to the mouthfeel, colour and stability of red wines; some of them also exhibit potent biological activities (Gómez-Alonso et al, 2007). Phenolic compounds, mostly originating from grape berries, are transferred into wine during the winemaking process (Salas et al, 2003). The main phenolic compounds in red grapes and red wine are anthocyanins and non-anthocyanins, which include flavonols, flavan-3-ols, phenolic acids (including hydroxycinnamic acids and hydroxybenzoic acids) and stilbenes (Monagas et al, 2005;Li et al, 2011;Zhang et al, 2015).…”