The impact of nitrogen on yeast fermentation and wine quality

Wine aroma is composed of primary, or varietal, aromas that arise directly from the grapes; secondary, or fermentation aromas, aromas produced by yeasts during the alcoholic fermentation; and the tertiary, or maturation bouquet that results from chemical reactions during wine ageing. Organic acids, higher alcohols, low-volatile organic sulphur compounds and esters, with their fruity notes, are signifi cant sensorial components of wine and other fermented beverages and are the primary compounds that form a fermentation bouquet. At low levels, most of these compounds contribute to the perceived wine aroma, but at high levels, they can dominate the aroma, decreasing its complexity. The compounds are released during alcoholic fermentation in variable concentrations depending on the yeast strain, fermentation conditions, and nutrient concentration. The infl uence of nitrogen on alcoholic fermentation and aroma compound formation by yeast, and therefore its effect on wine quality, is discussed herein