SO2 is once again an excellent means of protection against excess oxygen. However, other antioxidants exist.
Glutathione, for example, produced naturally by yeast during alcoholic fermentation, is a powerful antioxidant. When alcoholic fermentation is rapid and vigorous, glutathione is present in greater quantities. The yeast strain also has a significant impact on glutathione production.
The ellagitanins present in the wood are also powerful antioxidants. Other phenolic compounds in wine react with oxygen. The different compounds have been detailed in the section on Choice of extraction procedure.
Other molecules have the opposite effect and catalyze oxidation reactions, such as metals like copper and iron. It is necessary to be vigilant on this point. When tools were made of iron rather than stainless steel, iron caused significant problems. This is now less of an issue.