Käymistyyppi

Käymistyyppi refers to the different types of fermentation processes used in food and beverage production. Primarily, these are categorized into two main groups: aerobic and anaerobic fermentation. Aerobic fermentation requires the presence of oxygen, while anaerobic fermentation occurs in the absence of oxygen.

In the context of beverages, particularly beer and wine, the term "käymistyyppi" most commonly distinguishes between top-fermenting and bottom-fermenting yeasts. Top-fermenting yeasts, scientifically known as *Saccharomyces cerevisiae*, are used in the production of ales and some other beverages. They ferment at warmer temperatures and produce a frothy head that rises to the top of the fermenter, hence the name. These yeasts typically ferment faster and contribute fruity and spicy flavor compounds.

Bottom-fermenting yeasts, such as *Saccharomyces pastorianus* (formerly *Saccharomyces carlsbergensis*), are used for lagers. They ferment at cooler temperatures and tend to settle at the bottom of the fermenter after fermentation is complete. This process is generally slower and results in cleaner, crisper flavors with less prominent fruity esters compared to ales. The choice of käymistyyppi significantly impacts the final flavor profile, aroma, and texture of the fermented product. Beyond these two primary types for beverages, fermentation is also crucial in producing other foods like yogurt, bread, and sauerkraut, each involving specific microorganisms and conditions.