🍷 Oenococcus oeni

Oenococcus oeni is the main lactic acid bacterium of wine. It is a micro-organism invisible to the eye but with an important role. It lives on grapes, on barrels and in the cellar, and tolerates conditions that kill many other bacteria: alcohol and acidity.

What does it do? It starts the malolactic fermentation, often called malo. The bacterium converts malic acid, sharp and green, into lactic acid, soft and round. The wine becomes less sour and the taste softer. Buttery notes may appear as a side effect.

This fermentation is especially important for red wines and some whites, such as Chardonnay, while in sparkling wines it is sometimes avoided to keep freshness. The winemaker can wait for the bacterium to settle on its own or add selected cultures.

Oenococcus oeni belongs to the lactic bacteria of wine as their main species. It is harmless to people: it is needed only by the wine.