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Dear Dr. Vinny,

I just read an article on malolactic conversion and I have seen this on the back of some wine bottles. Just how many wineries use this process? I thought it was something that would be of interest to wine tasters like myself.

—Scott, San Marcos, Calif.

Dear Scott,

Malolactic fermentation (the cool kids call it “ML”) takes place after the primary fermentation, which converts sugar to alcohol. In ML, bacteria convert the harsh malic acid (think tart green apples) into softer lactic acid (think cream). By the way, you’re right to call ML a “conversion,” as it’s not a true “fermentation.”

ML is pretty standard, and most red wines and many whites are intentionally put through ML to enhance their stability and complexity. If a wine is put through ML intentionally, it also helps prevent it from taking place later, accidentally, in the bottle, which can turn a wine into a cloudy, smelly, fizzy mess. There are still plenty of delicious wines that don’t go through ML, including some of my favorite crisp whites.

—Dr. Vinny

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