Oxidation

Oxidation is a chemical process in which wine comes into contact with oxygen. This process is a natural part of winemaking, as oxidation occurs during grape pressing and subsequently during fermentation and aging. Mild oxidation can be beneficial for wine, as it helps develop its flavor and aroma, but excessive oxidation can cause undesirable changes in the wine's flavor and color, leading to its deterioration.

In the case of excessive oxidation, young white wines acquire a pink-orange hue, while red wines turn brown. Such wine has a high content of volatile acids, which are manifested by a smell reminiscent of vinegar or acetone, and the taste is dull and unpleasant. The term "oxidized wine" is used for wines that are aged and dead, and this term has a rather negative connotation among experts.

Although a slight contact of wine with air is often desirable and helps the wine in the aging process, oxidation must be carefully controlled. Uncontrolled oxidation can occur during vinification in a tank, barrel, or even after bottling if the cork does not seal well. For some types of wines, such as Madeira, Vin Santo, or straw wine, the oxidation process is deliberately used to achieve specific flavor properties.