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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 polysaccharides 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.

A current research interest of the wine industry is the improvement of wine quality by producing wines to meet the consumers’ demands and desires. However, this requires an understanding of the complex chemical matrix and the nature of interactions between molecular components of the wine. Wine polysaccharides are macromolecules whose presence and interactions with other wine components can lead to the modulation of technological and organoleptic wine quality attributes. Indeed, grape and yeast derived polysaccharides play a major role in modulating wine astringency through interactions with exogenous salivary protein-tannin complexes formed within the oral cavity. Polysaccharides participate in the formation of colloidal particles through their interactions with wine tannins and proteins, with crucial implications on the clarity and stability of finished wines. Additionally, polysaccharides modulate wine aroma volatility and foaming. The extent to which they influence these attributes is dependent on the concentration and physico-chemical properties of all the species involved in these interactions. Overall, the structure, size and type of the polysaccharides are key components governing the success and intensity of their interactions with other species. Therefore, to better understand the relevance of polysaccharides in wine, this review discusses the molecular interactions facilitated by these species and details their potential roles within the wine matrix.