Bottom fermenting yeasts

Bottom-fermenting yeasts are brewer’s yeasts (Saccharomyces pastorianus, historically grouped under Saccharomyces spp.) that flocculate and collect at the bottom of the fermentation vessel during beer fermentation. They ferment at cool temperatures, typically 8–14 °C, producing the clean flavour profile characteristic of lagers and related beer styles. Their sedimentation behaviour simplifies yeast cropping and reuse across fermentations. Breweries manage yeast health through propagation hygiene, pitching-rate control, and monitoring of viability and vitality, since stressed yeast generates off-flavours such as diacetyl and sulfur compounds.