Changes in polysaccharides, tannin and total phenols throughout sur lies aging of Cabernet Sauvignon wine

Polysaccharides are one of the major classes of macromolecules found in wine. Often referred to as "protective colloids," these compounds have been known to play a critical role in stabilizing other molecules in solution. Interactions between polysaccharides and tannin have been demonstrated in model wine solutions, indicating potential effects on red wine composition. In this study, two common winemaking practices were used to modify polysaccharides and tannin in red wine: sur lies aging and enological tannin addition. By measuring the individual components of tannin, total phenols and polysaccharides in Cabernet Sauvignon wine throughout a twenty-week period of aging and routine mixing, the effects of these practices were related to polysaccharide-tannin interactions. Wines treated with lees resulted in a two-fold reduction of protein precipitable tannin, of which only 25% was recovered in the lees at the end of aging. Lees treated wines were also significantly higher in soluble polysaccharides, although, compositional analysis showed no significant increase of yeast-derived monosaccharides. Insoluble polysaccharides decreased throughout aging in all treatments, but were not compensated by any gain in soluble polysaccharides. Because of these inconsistent inventories, it is proposed that in the presence of excess polysaccharide, a strong interaction between polysaccharides and tannin molecules can exist in such a way that current methods to measure individual components in red wine are inadequate. This study also suggests that the addition of lees could potentially reduce astringency in red wine.