gjæres

Gjæres is the Norwegian term for fermentation, especially as driven by yeast. It refers to the process by which yeast metabolizes sugars to produce carbon dioxide and, in many cases, ethanol. In bread production, gjæring causes dough to rise as CO2 bubbles created by yeast are trapped by gluten; the ethanol produced largely dissipates during baking. In brewing and winemaking, fermentation converts fermentable sugars into alcohol and carbon dioxide, while also generating flavor compounds such as esters and phenols that shape aroma and taste.

The rate and character of gjæring depend on yeast strain, temperature, sugar content, moisture, and oxygen availability. Most baker’s yeast operates best around room temperature; cooler temperatures slow activity, while excessive warmth can stress or kill the yeast. Yeast strains commonly used in baking belong to Saccharomyces cerevisiae, though other yeasts and wild fermentations are employed to achieve different flavors in certain products.

Gjæres can be intentional and controlled in commercial bread, beer, and wine production, or spontaneous in traditional or artisanal preparations. The term encompasses both the active phase of fermentation and the overall process by which a dough, beverage, or other product develops its leavening, alcohol content, and flavor through yeast-driven fermentation.