Sugars in wine 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 composed of simple sugars. Both glucose and fructose are six-carbon
Quinta classification of Port vineyards in the Douro the permitted production level of the vineyard and what price the grower can receive for the wine they produce from the grapes. Quintas are given numerical ratings in several categories – age of the vines, altitude, aspect, vine density, gradient, granite content of the soil, schist content of the soil, types of grape varieties planted, overall location of the vineyard, microclimate, mixture, vineyard soil type, vine productivity, and vineyard maintenance. Vineyards that have favorable attributes in a particular category (such as being planted with an optimal low density of vines) are award points while negative attribute (such as having too