Justin Fay explains three things you may not know about yeast

The COVID-19 stay-at-home orders have fostered a trend of at-home baking, in which amateur breadmakers, like master bakers and brewers, are beginning to experiment with various strains of baker’s yeast and sourdough starters.

The strains of yeast used to make beer, bread, and wine come from the species of yeast called Saccharomyces cerevisiae. S. cerevisiae is known as “brewer’s yeast” or “baker’s yeast” for good reason: it’s responsible for the fermentation that makes beer alcoholic and allows a lump of dough to rise into a loaf of bread. In the presence of oxygen, S. cerevisiae converts sugars from a carbohydrate—such as flour involved in breadmaking or barley involved in beermaking—into carbon dioxide. The carbon dioxide inflates air bubbles within the dough, causing the dough to rise.

Justin Fay, a professor of biology at the University of Rochester, studies the complex ancestry of S. cerevisiae in order to tackle big questions about evolutionary biology, including how species differentiate.