Before it is bottled, wine can benefit from judicious exposure to oxygen at various times. One technique that's used is called "racking," in which the wine is moved from one barrel or tank to another. It's used to clarify the wine–the clear liquid is siphoned off from the dead yeast cells and other sediment that's collected at the bottom of the container–but racking also exposes the wine to oxygen. It's a very labor-intensive process.
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. Winemakers who use micro-oxygenation say it is more efficient and less damaging to the wine than racking.
Proponents also say the process helps stabilize color, minimizes green components in the wine and gives the wine softer, rounder, less aggressive tannins. There is the potential that the process can really damage the wine if not used properly, leaving it with an oxidized, stale, dried-out taste. It's not clear yet whether micro-oxygenation will shorten a wine's life span.
Micro-ox is popular in Bordeaux and is prominent in the documentary “Mondovino,” in which the famous consultant Michel Rolland is seen continually advising his Bordeaux clients to micro-oxygenate this or that barrel.
Primarily used in red wine production, micro-oxygenation can also be used for white wines to simulate the effects achieved through barrel aging. The value of this technique sparks debate in winemaking circles, but it appears to be here to stay, yet another tool in a winemaker's toolbox.
