Oxidation

Oxidation defines the reactions that take place in wine when exposed to oxygen. These reactions are desired to some controlled extent for certain wine styles such as Madeira and tawny port. Oxidation is considered detrimental for standard table wine styles though. The oxidation process will cause reactions in the phenolic chemical compounds present in wine that lead to browning of wine color. Exposed air spaces contacting wine will also begin the process of spoilage from Acetobacter microbes, which convert the ethanol in wine into vinegar. Oxidized wines are said to develop bruised apple/sherry-like aromas with an accompanying loss of fruit character. Oxidation in wine can be prevented by minimizing head spaces in the containers wine is stored and aged in. The headspaces that do exist can also be saturated with inert gas blankets of carbon dioxide, nitrogen, or argon on a regular basis. Inert gasses are commonly used to sweep oxygen from any tanks that finished wines are racked or transferred to during ageing and bottling of the wine.