Aeration

aeration, the deliberate and controlled exposure of a substance to air, and particularly to its reactive component oxygen.

The aeration of wine during winemaking must be carefully controlled, since excessive exposure to oxygen can result in oxidation and the possible formation of excess acetic acid. At the beginning of fermentation some aeration is necessary since yeast needs oxygen for growth. The cellar operation of topping up can expose the wine to an amount of oxygen that contributes to the barrel maturation process. The amount of aeration involved in the cellar techniques of racking wine from one container (usually a barrel) to another, délestage, and pumping over can also be positively beneficial to a wine’s development. Specifically, aeration can often cure wines suffering from reduction and can usually remove malodorous and volatile hydrogen sulfide and mercaptans.