Sugar

There would be no wine without the sugar in ripe grapes that the yeast feeds upon, excreting both alcohol and carbon dioxide a process called alcoholic fermentation. However, in entirely health grapes the sugar is only in the juice and the yeast are all outside the grape skin, so that to make wine the skisn must be broken by crushing them. Originally, this was done by human feet, but winemaking technology has advanced considerably during the last 6,000 years! Sometimes not all the sugar is converted into alcohol and the sugar that remains gives the wine a sweet taste that can be extremely pleasant. The technical name for this sweetness is residual sugar (RS).