Which yeast is used in baking and brewing?

The yeast used in baking and brewing is Saccharomyces cerevisiae. It is a single-celled fungus whose fermentation converts sugars into carbon dioxide and ethanol. In bread dough, the carbon dioxide becomes trapped in the gluten network, making the dough rise and producing a lighter loaf.

In brewing, S. cerevisiae is commonly called brewer’s yeast and is associated especially with ales. It is a top-fermenting yeast because cells and foam can rise toward the top of the vessel during fermentation. Lager production generally uses Saccharomyces pastorianus, a related yeast adapted to cooler, bottom-fermenting conditions.

Baking and brewing strains belong to the same species but have been selected for different traits, including fermentation speed, temperature tolerance, flavor production, and sugar use. The species has a long history: bakers historically obtained yeast-rich foam, or barm, from ale breweries.

The name Saccharomyces means “sugar fungus” in Latinized Greek. S. cerevisiae is also one of biology’s most important model organisms because it is a manageable eukaryotic cell with well-studied genetics.