Polysaccharides are carbohydrates, which are basically simple sugars, monosaccharides like glucose and fructose, linked together in long chains. Yeast can break these down into the simple sugars for use in creating ATP for reproduction. However, polysaccharides also react and combine with many endogenous compounds found in wine and cider. These include aroma compounds, tannins, and proteins, which impact the organoleptic characteristics(1). Common impacts are a reduction in astringency when certain polysaccharides join with different tannins. They also can suppress the release of volatile compounds by binding with aroma compounds. Another interesting aspect is how they can change foaming characteristics and wine clarity by combining with proteins.
There are two common sources for the polysaccharides found in wine and hard cider. The primary is the fruit. The cell walls and pectin structures release polysaccharides when they break down. The most common polysaccharides coming from the fruit are arabinogalactan proteins (AGP) and rhamnogalacturonans (RG-II). The addition of pectic enzymes and maceration are ways to increase the extraction of polysaccharides from the fruit. The other source is from the yeast. The most common polysaccharides coming from yeast are mannoproteins, glucans and mannans. Yeast cell walls can release these during the various fermentation phases as well as during another key process: autolysis. This process is enhanced by aging cider on the lees, especially the fine lees. It’s amazing the range of influence polysaccharides can have to your cider and how your process can impact the amount of polysaccharides you extract.
(1) H.R. Jones-Moore and associates, The interactions of wine polysaccharides with aroma compounds, tannins, and proteins, and their importance to winemaking, Food Hydrocolloids 123, 2022
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