Focus on the relationships between the cell wall composition in the extraction of anthocyanins and tannins from grape berries.

Concentrations of anthocyanins and tannins after extraction from berries in wines and from skin macerations in model solutions have been studied for two grape varieties, two maturation levels and two vintages berries. Characterization of the cell wall polysaccharides has also been performed, the classical method based on the analysis of the neutral sugars after depolymerization being completed by a comprehensive microarray polymer profiling (CoMPP). Extraction was lower in model solutions than in wines, with the same ranking: non acylated anthocyanins> tannins > p-coumaroylated anthocyanins.

Diffusion of phenolic compounds during a model maceration in winemaking: role of flesh and seeds.

Background: During red winemaking, diffusion of phenolic compounds from the grape berry cells into the liquid phase occurs simultaneously with the adsorption of the same compounds onto the pulp. In previous studies, we quantified the proportions of polyphenols diffusing from the skins and then assessed the amounts that can be fixed by the pulp. In this work, we added the impact of seeds, also present during vinification, by carrying out macerations in a model medium with the following berry compartments: skins, seeds, skins + seeds, skins + seeds + pulp.

Impact of the variety on the adsorption of anthocyanins and tannins on grape flesh cell walls.

Background: During winemaking, after extraction from the skins, anthocyanins and tannins adsorb onto the pulp flesh cell walls. The present study aimed to quantify the amounts adsorbed and their impact on wine composition, the impact of variety and ethanol on adsorption, and whether the presence of anthocyanins plays a role and impacts tannin adsorption.

Results: Anthocyanin and tannin fractions obtained by mimicking winemaking conditions were mixed with fresh flesh cell walls of two varieties: Carignan and Grenache.

Impact of grape variety, berry maturity and size on the extractability of skin polyphenols during model wine-like maceration experiments.

Background: Skin cell walls modulate anthocyanin and tannin extraction from grape skins. However, relationships between the composition of alcohol-insoluble cell wall solids (AIS) and extraction are still unclear. Our objectives were to characterize the impact of variety, berry size and ripeness on skin AIS composition (polysaccharides, proteins) and polyphenol extraction during maceration.