Influence of grape maturity and maceration length on polysaccharide composition of cabernet sauvignon red wines

Cabernet Sauvignon grapes were harvested at three different degrees of maturity (~three, five, and seven weeks postveraison) and used for micro-scale vinifications. For each maturity, four different maceration lengths (one, two, three, and four weeks) were applied in triplicate to assess the influence of both maceration length and grape maturity on the composition of wine polysaccharides. The total concentration of wine polysaccharides was estimated by high resolution size exclusion chromatography-refraction index detection and the polysaccharides then underwent acidic hydrolysis. The neutral monosaccharides released were analyzed by ion exclusion chromatography using an HPLC-RID chromatographic system. The total concentration of wine polysaccharides increases with maceration length and with grape maturity. Both yeast polysaccharides (mannoproteins, MP) and some grape polysaccharides (polysaccharides rich in arabinose and galactose, PRAGs) increase with maceration length. However, grape maturity affects PRAGs and MPs differently: while PRAGs increase with the grape’s maturity, the opposite appears to be true of yeast polysaccharides.