What is Malolactic Fermentation
You may not know it, but you probably love it.
by Erin Henderson
Malolactic fermentation (MLF), or malo as the cool kids say, is one of those hazy terms that is liberally bantered about by wine pros, yet few wine lovers know what it is.
And more confusingly, it's not actually fermentation.
So what is it, and why do we care?
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At the most basic, malo is a bacterial conversion which turns a wine's sharp malic acid (like the kind found in tart green apples) into a creamier, smoother lactic acid (like the kind found in milk.)
MLF is used in wines, some white and many red wines, to reduce the edge of the wine and promote a softer mouthfeel. And if we want to really nerd out, malolactic fermentation creates seomthing called diacetyl an organic compound that promotes a buttery taste in wine. But let's not confuse things.
Nearly all red wines undergo MLF because we like the rich rexture it produces; it's far more appealling to enjoy a plush Shiraz, for example, than one with a texture of a razor's edge. And the same goes for white wines; Chardonnay is proabably the most obvious example, but Chenin Blanc, Pinot Gris, Viognier, and even some Champagne all go through malo, for that desirable creamy mouthfeel.
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Interestingly, the process of malolactic fermentation is a contributing factor to long-lived wines; wines are stabalized so they can gain complexity as they age without spoiling.
Where MLF is typically avoided is with wines where we want that fresh, racy character: Sauvignon Blanc, Riesling, and most rosé, for example.
As with all things wine, it's not that malolactic fermentation is a better or worse way to make wine. It's simply another tool in the winemaker's toolbox which allows her to create a specific outcome.
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