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“Hi, Karen. Why is malolactic conversion often referred to as a fermentation, when the definition of fermentation implies the creation of alcohol, which does not occur during malo?”—Tyler R. (Sebastopol, CA)

Hi Tyler, great question. The fermentation in which yeasts convert sugar in grapes to alcohol is technically called the primary fermentation. Malolactic fermentation is often referred to as a “second fermentation.” It’s conducted by bacteria which convert malic acid to lactic acid. So the key question is: what is fermentation exactly?

We posed this question to Napa Valley winemaker Cathy Corison (Corison winery) who responded:  “Fermentation is the conversion of one compound to another by a microbe. Even chocolate production involves a fermentation! Malolactic is one of many lactic fermentations that are responsible for cheese, pickles and yogurt, among many other things.” So there you have it. Malolactic fermentation IS indeed a fermentation.—Karen

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