A brewer watches beer bottles track down a factory line. (Credit: Jacob Lund/Shutterstock) Whether your preferred pint is crisp or hoppy, fruity or caramelly, you owe a lot to the single-celled fungus doing the important work of putting the booze in your brews. Hops may get most of the love on the craft beer scene, but yeast is an overlooked heavy-hitter when it comes to giving beer flavor. “Cool people are obsessed with yeast,” says Simon McConico, co-owner of Milwaukee’s Vennture Brew. “It’s because hops are sexy; yeast is a bit more nuanced.” He adds, “Yeast is starting to get more sexy among nerds.” Scientists are buying in, too. Ever since a microbiology expedition to the mountains of Patagonia uncovered a new wild yeast species in 2011, scientists have been hard at work on ingredients that may soon bring totally new flavors to a beer near you.
Saccharomyces cerevisiae, also known as brewer's yeast, has long been vital for making ale, wine and bread. (Credit: Illustration by Kateryna Kon/Shutterstock)
Yeast 101
The art of brewing can be broken down into a just a few key steps. First, grains are soaked until they start to germinate; then they’re roasted. Roasting is the first beer flavor checkpoint: lighter roasts might get turned into pale ales or pilsners; darker roasts into porters and stouts. Then this malt gets mashed and boiled, which converts the starches in the grain into sugars. Hops are added to make the wort — hot, sweet food for yeast. That’s when it’s ready-to-ferment. Yeast arrives and eats up the sugars, turning them into alcohol, carbon dioxide and flavor compounds. However, just two yeast species are currently used to make beer: Brewer’s yeast (Saccharomyces cerevisiae) and lager yeast (Saccharomyces pastorianus.) The former comes in hundreds of strains, which can impart all sorts of different flavors on a beer.
