Is Yeast Boosting Alcohol Levels?
There’s a long string of factors involved in the rising tide of high-alcohol wines–but yeast isn’t one of them. It’s not hard to find winemakers who will tell you that among the things ratcheting up the ethanol levels these days is the tendency of current-release commercial yeast strains to be more efficient at converting sugar to alcohol–more bang for the Brix. Nobody claims that’s the whole story, but this theory shows up on just about every list.