The impact of cell wall composition of the extraction of anthocyanins and tannins from grape berries

Abstract

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, using UHPLC-MS/MS in the MRM mode  and HPSEC. 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 higher quantities than non acylated. Maturation led to an increase of quantities 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 extraction yields of non acylated anthocyanins in model solutions and in wines were higher than those of tannins. Percents of 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, not in berries. P.coumaroylated anthocyanins recoveries were lower in model solutions than in wines. The cell wall structure was related to the mechanism of extraction. 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. Arabinose % was correlated positively, mannose % and glucose % negatively to the recovery of all anthocyanins and tannins in model solution, to p.coumaroylated anthocyanins only in wines. These results trigger questions.
Firstly, the lower recovery of p.coumaroylated anthocyanins may be due to the hydrophobicity of the coumaroyl unit, modifying their interactions with other polyphenols and/or with the cell walls.
Secondly, p.coumaroylated anthocyanin recoveries were very different in model solutions and in wines. Pulp, seeds and/or yeasts present in wines should play a role in their extractibility.
Thirdly, anthocyanins/tannins extracted in model solutions/wines were correlated to several parameters describing the cell walls, among them their compositions measured by the neutral sugars and their structures measured by the CoMPPs. To conclude, this study confirms with more details the major role that play cell walls in the extraction of anthocyanins and tannins.

The impact of cell wall composition of the extraction of anthocyanins and tannins from grape berries

Abstract

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