Word of the Week: Malolactic Fermentation

Also referred to as “malolactic conversion” or “secondary fermentation” – as well as “ML” or “malo” in wine slang – malolactic fermentation is the process by which a wine’s tart malic acids are converted to softer lactic acids. The conversion is carried out by lactic acid bacteria, which often grow naturally inside a winery and will proceed spontaneously, or can be cultured for inoculation. Malolactic isn’t technically a true fermentation process, although like alcoholic fermentation, carbon dioxide is released as a byproduct. Malolactic fermentation typically commences either during or subsequent to alcoholic fermentation. While malolactic fermentation is a nearly universal practice for red winemaking, it remains a stylistic choice for white wines. Malolactic fermentation lowers a wine’s total acidity, as well as changes its texture and flavor profile. Wines that have undergone malolactic conversion will typically taste rounder and fuller, and winemakers in warmer sites may choose to forego the practice in order to preserve a wine’s freshness. That super creamy California Chardonnay you love has likely been subject to malolactic fermentation, whereas a crisp, zippy New Zealand Sauvignon Blanc likely has not.