Editor's Note: Our Science Editor, Tom Mansell, explored the world of sour beers after a visit to the Great American Beer Festival. From fermentation to aging, Tom described sour beers as a bridge between the beer and wine worlds. This article is a must read for wine drinkers and beer drinkers alike who feel they just "don't get" the other side. –Ryan Reichert, Managing Editor
Today, we’re far more likely to find toasty, bready flavors in a more fashionable (and still seasonally appropriate) beverage: methode champenoise sparkling wine. How those characteristic flavors get there has nothing to do with actual toast and everything to do with yeast.
From a certain point of view, winemakers don’t make wine; yeast and bacteria do. Juice becomes wine by the miracle that is fermentation, the conversion of sugar to alcohol and other compounds. Since I’ve yet to see a human person ingest sugar and expectorate alcohol (whoa…don’t follow that mental image), winemakers must delegate this key operation to yeast.
Open a refrigerator in the back of many wineries and you may find some leftover pizza, cheese and fruit for tomorrow evening’s mixer, and a few rectangular foil packages that look suspiciously like bread-baking yeast. However, those packages of yeast—and they are yeast—are for the wine, not bread dough.