Micro-oxygenation is a process used in winemaking to introduce a controlled amount of oxygen into wine. Developed by Patrick DuCournau in 1991, working with the exceptionally tannic grape Tannat in Madiran, France. The process began in winemaking following the 1996 authorization by the European Commission. Today the technique is widely employed in Bordeaux as well as in several different countries.
The purpose of micro-oxygenation is to bring about desirable changes in wine texture and aroma. The objectives include improved mouth-feel (body and texture), enhanced colour stability, increased oxidative stability, and decreased vegetative aroma. As treatment proceeds, one observes an increase of the aromatic intensity and palate complexity.
The tannins become softer, the body of the wine is increased and a rounder mouth-feel. The exposure of wine to oxygen in limited quantities can be beneficial - though too much oxygen can lead to oxidation and too little can lead to reduction and wine faults.
In oak barrel aging, the natural properties of the wood allows for a gentle aeration of the wine to occur over a long period. This aids in the polymerization of tannin into larger molecules, which are perceived on the palate as softer in character.
Micro-oxygenation aims to mimic the effects of slow barrel maturation in a shorter period and at a lower cost associated with oak barrels. It also enables more control, as opposed to barely observing it in an oak barrel.
The process of micro-oxygenation involves a large two chamber device with valves interconnected to a tank of oxygen. In the first chamber the oxygen is calibrated to match the volume of the wine. In the second chamber the oxygen is injected into the wine through a porous ceramic stone located at the bottom of the chamber.
The dosage is controlled, ranging from 0.75 to 3 cubic cm/ litre of wine. The process normally occurs in multiple treatments during the early stages of fermentation (to help avoid stuck fermentation) - to a more prolonged treatment during maturation.