What is malolactic fermentation (secondary fermentation)?

What is malolactic fermentation (secondary fermentation)?

• A. Occurs during or after fermentation, lactic acid bacteria convert harsh malic acids into softer lactic acids and carbon dioxide.
• B. Occurs during primary fermentation, yeast convert sugars to alcohol
• C. A chemical oxidation of ethanol to acetic acid
• D. A filtration step to remove solids

Answer: (A)

Malolactic fermentation is a secondary process in winemaking where lactic acid bacteria act on the wine after or toward the end of the primary fermentation by yeast. They convert malic acid, which tastes sharp and tart, into lactic acid, which is softer, releasing carbon dioxide in the process. This shift reduces overall acidity and can smooth the wine’s mouthfeel, sometimes adding additional flavors such as buttery notes from diacetyl. It is different from the primary fermentation, which is yeast turning sugars into alcohol, and it is not a chemical oxidation of ethanol to acetic acid nor a filtration step.

Malolactic fermentation is a secondary process in winemaking where lactic acid bacteria act on the wine after or toward the end of the primary fermentation by yeast. They convert malic acid, which tastes sharp and tart, into lactic acid, which is softer, releasing carbon dioxide in the process. This shift reduces overall acidity and can smooth the wine’s mouthfeel, sometimes adding additional flavors such as buttery notes from diacetyl. It is different from the primary fermentation, which is yeast turning sugars into alcohol, and it is not a chemical oxidation of ethanol to acetic acid nor a filtration step.