Oxidation

Oxidation is the changes that happen when wine comes into contact with oxygen. It is the same process you know from a cut apple or a banana turning brown, and in wine it shows up as changes in colour, aroma and taste. A small amount of oxygen during maturation is often beneficial and helps make the wine rounder and more complex. Too much oxygen, on the other hand, pulls the wine in the wrong direction, and it loses its freshness.

You can often recognise an oxidised wine by its colour and aroma. A white wine that has had too much oxygen turns darker and more golden or brownish, while a red wine can seem dull and brick-red at the rim. The aroma loses its fresh fruit and instead resembles brown apples, nuts or sherry. In some types of wine the nutty note is precisely what is wanted, but in an ordinary fresh white wine it is a sign that the wine has passed its best.

To manage oxidation, winemakers use, among other things, sulphur (SO2), which acts as an antioxidant and protects the wine from oxygen during storage and after bottling. A common misunderstanding is that all contact with oxygen is harmful. In reality it is about balance, where small, controlled amounts of oxygen contribute positively, while uncontrolled oxidation ruins the wine.