slutjäsning

Slutjäsning, literally “final fermentation,” is a term used in Swedish fermentation science and industry to describe the last phase of a fermentation process after the main, or primary, fermentation has begun to wind down. The exact meaning can vary by sector, but it generally denotes the period when fermentation activity slows significantly, remaining sugar may be depleted or nearly so, and flavors and textures continue to develop as the product approaches its final composition.

In practice, slutjäsning is most commonly discussed in contexts such as brewing, winemaking, and other fermentations where a late-stage maturation occurs. During this phase, residual reactions continue, sometimes including slow sugar consumption, continued CO2 production, and changes in aroma and mouthfeel. Temperature control, nutrient availability, yeast or microbial strain, and oxygen exposure influence the duration and character of this final stage.

Monitoring slutjäsning typically involves periodic measurements such as gravity or density readings to track residual fermentable sugars, observations of gas production, and sensory evaluation of aroma and flavor development. Proper management aims to avoid stuck fermentations, which can occur if conditions become unfavorable, and to ensure a stable end product with the desired carbonation, acidity, and stability.

Related terms include primary fermentation, secondary fermentation, and maturation. Because usage varies between producers and industries, some sources reserve slutjäsning for a specific late-stage process, while others use it more broadly to refer to the final stabilization period of fermentation.