A large part of the science, and the art, of winemaking has to do with managing exposure to oxygen. The detrimental effects of excessive oxygen - in the form of browning, development of aldehyde aromas, and the loss of fruit flavour - have been recognised since Pasteur (Halliday and Johnson, 2003). Preventing oxygen contact is the primary concern of modern reductive methods for making wine. This is especially true of most contemporary white winemaking in the New World. On the other hand, winemakers deliberately encourage oxygen exposure at certain steps in the production process.

Many of the benefits of wine maturation in oak barrels are due to the slow permeation of oxygen through the barrel walls but long-term bottle ageing then takes place in a predominantly oxygen-free environment. Once opened, however, a short period of air contact, in the form of decanting or ‘breathing’, is thought to improve wine quality before consumption. Clearly, winemaking is a complex balance between protection from oxygen and controlled aeration so that any oxygen exposure during winemaking requires careful consideration with regard to dose and timing.

Microbullage
 n.— «Micro-oxygenation (also known as micro-ox or by the French term microbullage) involves a machine developed in France that dispenses tiny, precise amounts of oxygen.

Micro-oxygenation is a new, innovative wine-making technique which involves the controlled introduction of low concentrations of oxygen during early wine maturation. It is claimed that micro-oxygenation can reproduce the benefits of barrel-aging but in a much shorter time and at a fraction of the cost. Micro-oxygenation is supposed to result in wines with soft, accessible tannins as well as greater colour stability which is obviously appealing to winemakers vying for a share of the increasingly competitive global market. The technique was originally developed in France but is now used throughout the world including South Africa.