Sugars in wine The technique allows for a better extraction of wine polysaccharides. Sugars in wine Sugars in wine are at the heart of what makes winemaking possible. During the process of fermentation, sugars from wine grapes are broken down and converted by yeast into alcohol (ethanol) and carbon dioxide. Grapes accumulate sugars as they grow on the grapevine through the translocation of sucrose molecules that are produced by photosynthesis from the leaves. During ripening the sucrose molecules are hydrolyzed (separated) by the enzyme invertase into glucose and fructose. By the time of harvest, between 15 and 25% of the grape will be
History of the wine press Terentius Varro, Pliny the Elder and others described wooden wine presses that utilized large beams, capstans and windlasses to exert pressure on the pomace. The wines produced by these presses were usually darker, with more color extracted from the skins but could also be more harsh with bitter tannins also extracted. That style of wine press would eventually evolve into the basket press used in the Middle Ages by wine estates of the nobility and Catholic Church leading to the modern tank batch and continuous presses used in wineries today. The exact origins of winemaking (and, thus, of pressing grapes)