The polysaccharides of winemaking: From grape to wine

Background: Polysaccharides are a major class of complex macromolecules present in the wine matrix. These polysaccharides can be classified as being either grape or yeast derived. The key polysaccharides identified within the wine matrix are the pectic polysaccharides: polysaccharides rich in arabinose and galactose (PRAG), rhamnogalactouronans (RG-I and RG-II) and yeast mannoproteins (MP). The transformation of grapes into wine induces significant changes in the chemical composition and profile of these polysaccharides. Scope and approach: This review aims to summarise and discuss the prevalence of polysaccharides in wine, with a focus on their profile during the transformation from grape to wine. This study emphasises the chemical complexity of the wine matrix, highlighting the many factors influencing the profile and abundance of poly-saccharides which could in turn assist winemakers in making informed decisions. Key findings and conclusions: Many factors during grape maturation and throughout the winemaking process have been shown to influence the profile and chemical composition of polysaccharides. Environmental factors can significantly influence the polysaccharide profile of grape berries prior to harvest. Fermentation is responsible for the largest modification in the polysaccharide profile throughout vinification. Overall, the transition of must to wine is characterised by an increase in grape derived AGPs and RG-II, as well as a dramatic and progressive increase in yeast MP, especially true for wines aged on yeast lees