Malolactic Fermentation

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When reading technical wine sheets, we often come across the concept of ‘malolactic fermentation.’ Either to explain that the wine underwent this process (nearly always in reds) or that it has not (mostly in whites). This might seem confusing since malo-lactic sounds more related to milk than to wine. So it’s only natural to ask yourself about the meaning of this concept or what its purpose might be. To begin, and said in simple words, malolactic fermentation is a process by which the tart malic acid –present in the grape- is transformed into lactic acid (in fact, the same acid present in milk), much softer and creamier. 

Despite its name, malolactic fermentation is not technically a fermentation process since it does not involve yeasts but bacteria. The most important being oenoccocus oeni, although other strains of lactobacilli are also involved in this process. They feed on malic acid and return it to the wine in the form of lactic acid after digesting it.

Practically all red wines undergo malolactic fermentation as it provides that pleasant creamy and velvety feeling on the mid-palate. In red wines, this process, which also helps the microbiological stabilization of the wine, should occur during the aging period, either in barrels, foudres, cement eggs, or stainless steel tanks. In any case, always before bottling.

Among whites, malolactic fermentation used to be mandatory for wines made with Chardonnay and Viognier. Nowadays, especially in regions with warmer climates, where grapes lose more quickly their tartaric acidity (another of the many organic acids present in wine), malolactic fermentation tends to be avoided (totally or partially) to preserve the wine’s freshness. On the other hand, wines made with Chardonnay, originated in regions with very cold climates, such as Chablis, could be really unpleasant if they didn’t accomplish malolactic fermentation. Sauvignon Blancs, of which you expect good acidities, are generally not induced to undergo malolactic fermentation.

At Morandé Wine Group we have different ways of approaching malolactic fermentation.

For example, Jorge Martínez, winemaker at Viña Mancura, refers to Guardián, one of the winery’s emblematic wines, made with Carignan: “This is a variety whose characteristic is to have high acidity (also expressed as low pH). Hence, to ensure that malolactic fermentation really takes place, we inoculate the bacteria responsible for this process along with the yeasts that produce the alcoholic fermentation. Thus, once the must has been transformed into wine, it immediately follows the process that turns this beverage –initially full of edges- into a polished, smooth and elegant wine in the glass.”

On his part, Cristián Carrasco, winemaker at Viña Vistamar, declares that he does not always use this method, especially if making wines with traditional grapes, such as Carmenère or Cabernet Sauvignon. “These varieties usually have lower acidity (expressed as high pH), so the malolactic fermentation begins spontaneously, thanks to the bacteria that exist in the environment of the winery”.

Both winemakers agree that, once the intense activity developed by the alcoholic fermentation finishes, there is still a long time to go to transform the fermented juice of the grapes into the wines that we so much love to uncork.

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