Definition: Ester

A chemical compound resulting from the combination of an acid and an alcohol, or from the dehydration of two alcohol molecules. Esters, which are the main components of an alcohol's aroma, develop during distillation and maturation. Wine esters have three different origins: a small amount is found in the aromatic essences of grapes; another fraction is formed during fermentation by yeasts; a third comes from the chemical reaction of the acids in wine with the alcohol in wine. Although esters contribute to primary and secondary aromas, slow chemical esterification plays virtually no role in the development of bouquet. Volatile components of wine that cause bouquet and aroma.