Fermentables

Fermentables are ingredients that yeast can convert into alcohol and carbon dioxide during fermentation. In brewing and other fermentations, fermentables refer to fermentable sugars and related carbohydrates that contribute to the wort or mash, influencing gravity, attenuation, body, and flavor. The term helps distinguish components that yeast can metabolize from those that largely remain as body-enhancing non-fermentables.

Common sources of fermentables include malted grains (primarily barley, but also wheat, rye, oats, and other cereals) and malt extracts. These provide a mix of fermentable sugars and dextrins, created during mashing when enzymes convert starches to sugars. Additional fermentables include adjuncts and sugars such as corn and rice syrups, cane or beet sugar, honey, maple syrup, molasses, agave, fruit sugars, and other syrups. Some ingredients are more fermentable than others, and others contribute non-fermentable carbohydrates that remain in the final product to affect mouthfeel and body.

Processing and technique influence fermentability. Mash temperature and duration determine how completely starches break down into fermentable sugars; higher mash temperatures favor less fermentable dextrins, yielding fuller-bodied beers with higher final gravity. In contrast, more fermentable extracts and sugars lead to higher attenuation and drier profiles.

Fermentables are contrasted with non-fermentables, such as many dextrins from certain specialty malts, which yeast cannot fully ferment. Together, the selection and proportion of fermentables shape a beverage’s gravity, attenuation, flavor, color, and mouthfeel. In winemaking or other fermentations, fermentables generally refer to sugars that yeast can metabolize, including glucose, fructose, and sucrose.