What type of yeast is used in the fermentation of Kölsch?

Kölsch is a style of beer that traditionally employs ale yeast, specifically a type of top-fermenting yeast known as Saccharomyces cerevisiae. This yeast operates at warmer fermentation temperatures, typically between 60-75°F (15-24°C), which is characteristic of ales. The fermentation process for Kölsch generally results in a clean, crisp flavor profile, but the use of ale yeast also allows for some fruity esters and phenolic compounds, albeit in a restrained manner compared to other ale styles.

While Kölsch is brewed as an ale, it is often fermented at lower temperatures compared to typical ales, bridging the gap between ale and lager characteristics. This hybrid approach leads to its unique profile but does not change the fundamental classification of the yeast used, which remains ale yeast. The style’s traditional brewing method also includes lagering processes after fermentation to enhance clarity and crispness, but this does not alter the type of yeast originally used for fermentation.

Other yeast types such as lager yeast (Saccharomyces pastorianus) ferment at lower temperatures and produce different flavors, while wild yeast varieties introduce unpredictable and often sour characteristics, which are not necessary in a Kölsch. Hybrid yeast could refer to strains created from ale and