Martin Crook places fermented merlot grapes into a bladder press at the Brooklyn Winery in New York, Oct. 20, 2010. Wineries and winemaking schools are offering chances to buy in on a barrel and help produce it, from vine to glass. (ROBERT STOLARIK/NYT)
If a wine goes through malolactic fermentation and contains lactic acid, is it unsafe for people who are lactose intolerant like me?
No. You are perfectly safe to drink that wine, gastrointestinally speaking. There’s a big difference between lactose, which gives trouble to people in your situation, and lactic acid.
Lactose is a complex sugar found in dairy and must be broken down in the small intestine into its constituent parts, glucose and galactose, before it can be absorbed. The chemical knife needed to slice that sweetly seductive lactose, incidentally, is an enzyme called lactase. (I admit, the scientific nomenclature here could have been less confusing than most of my university chemistry lectures, but that’s science for you.) If, as many people do, you lack the ability to break down lactose, you’re in for bowel distress when you order a tasty triple-fudge milkshake or Tim Horton’s Iced Capp. Lactic acid, which is found in even more delicious wine, by contrast, need not be broken down to be absorbed by the body.
You may be wondering why wines contain lactic acid in the first place. The substance is produced by natural bacteria that begin fermenting in the wine following the primary alcoholic fermentation, in which yeasts gobble grape sugars to produce alcohol and carbon dioxide. As the name implies, malolactic fermentation converts tart, apple-like malic acid into softer, buttery lactic acid. With some wines that are intended to be crisp, such as riesling and sauvignon blanc, winemakers will suppress malolactic fermentation. But in such wines as chardonnay and merlot, the creamy texture is considered desirable.