Résumé
Extraction of anthocyanins and tannins have been studied for two grape varieties, Carignan and Grenache, two maturation levels and two vintages, in model solutions and in wines. The cell wall polysaccharides were characterized using the neutral sugar composition after depolymerization and the comprehensive microarray polymer profiling (CoMPP).Carignan was richer than Grenache in anthocyanins for both years. Berry anthocyanins were mainly non acylated and para coumaroylated. In Carignan, p.coumaroylated were found in most cases in higher quantities than non acylated. Maturation led to an increase of non acylated anthocyanins for Carignan and Grenache, and a slight decrease of p.coumaroylated for Carignan. No significant difference of their tannin composition was observed. The recovery yields of non acylated anthocyanins in model solutions and in wines were higher than those of tannins . Recoveries of p.coumaroylated anthocyanins were lower than non acylated anthocyanins and tannins, and lower in model solutions than in wine. Recoveries were higher in 2019 than in 2018.Correlations were observed between non acylated, p.coumaroylated and tannins concentrations in model solutions and wines while such correlation did not exist in berries. Therefore this suggests an underlying mechanism controlling the extraction, whose rules were a bit different in model solutions and in wines. Let us recall that pulps, seeds and yeasts were present in wines, not in model solutions.The cell wall structure would be related to such mechanism. Extraction of anthocyanins and tannins was correlated to high levels of homogalacturonans partially esterified in the skins (e.g. LM19-CDTA-skin) but low levels in the pulps, and by low levels of extensins in the skin (e.g. JIM11-NaOH-pulp) but high levels in the pulps. In model solutions, arabinose % was correlated positively, mannose % and glucose % negatively to the recovery of non acylated, p.coumaroylated anthocyanins and tannins. Such trend was observed for wines, but for the p.coumaroylated anthocyanins only.This study points out some interesting results which triggers questions. The first result is the significant lower recovery of p.coumaroylated anthocyanins. The difference with a non acylated anthocyanin lies in the p.coumaroyl unit. With this unit, the anthocyanin becomes more hydrophobic and so it can be expected that its interactions with other polyphenols and/or with the cell walls be modified when compared to a non acylated anthocyanin .A second interesting feature of p.coumaroylated anthocyanins is the difference of their recovery: low in wines but almost negligeable in model solutions. To explain this, pulp, seeds and/or yeasts present in wines should play a role in their extractibility. A third result is the correlations observed between anthocyanins/tannins extracted in model solutions/wines and several parameters describing the cell walls, among them their compositions measured by the neutral sugars and their functionalities measured by the CoMPPs.To conclude, this study brings clues, but does not unveil the mechanisms explaining the recovery of anthocyanins and tannins in model solutions and in wines. Among the possible scenarii, one will be suggested .