Acids in wine ripened grapes. While concentration varies among grape varieties, it is usually found in higher levels with red wine grapes. The acid is created as a byproduct of the metabolization of nitrogen by yeast cells during fermentation. The combination of succinic acid with one molecule of ethanol will create the ester mono-ethyl succinate responsible for a mild, fruit aroma in wines. Acidity is highest in wine grapes just before the start of "veraison", which ushers in the ripening period of the annual cycle of grape vines. As the grapes ripen, their sugar levels increase and their acidity levels decrease. Through the
Phenolic content in wine the methods of production, wine type, grape varieties, ageing processes, the following phenolics can be found in wine. The list, sorted in alphabetical order of common names, is not exhaustive. Phenolic compounds may interact with volatiles and contribute to the specific release of aromas in a wine. Although phenolics are speculated to provide antioxidant benefits from consuming wine, no evidence exists to date that wine phenolics actually have any effect in humans. Phenolic content in wine The phenolic content in wine refers to the phenolic compounds—natural phenol and polyphenols—in wine, which include a large group of several hundred chemical compounds