Cofermenting

Cofermenting, or cofermentation, is the process of fermenting a substrate with two or more distinct microorganisms at the same time. This approach leverages interactions among species—such as competition, cooperation, and cross-feeding—to produce a broader range of metabolites, which can influence flavor, aroma, texture, acidity, and alcohol content. Cofermenting is commonly used with yeast and lactic acid bacteria, but it can involve molds or propionic bacteria as well. It contrasts with monoculture fermentation by introducing simultaneous biological activity from multiple players.

Applications include alcoholic beverages such as beer and wine, and fermented foods. In beer, cofermentation often combines different Saccharomyces strains or adds non-Saccharomyces yeasts to create complex ester profiles. Some sour beers use lactic acid bacteria alongside yeasts to develop acidity and funk. In wine, malolactic fermentation is a form of cofermentation that occurs after primary fermentation, in which Oenococcus oeni (lactic acid bacteria) converts malic acid to lactic acid, softening acidity. In dairy and plant-based products, yogurt, kefir, and certain cheeses rely on cofermentation between lactic acid bacteria and yeasts or other bacteria to build texture and tang. Cofermentation is also used in fermentations like kimchi, sauerkraut, and miso, where diverse microbial communities act together.

Important considerations include controlling inoculation ratios, pH, temperature, oxygen, and nutrient availability to balance growth and prevent spoilage or off-flavors. Safety and regulatory aspects depend on the organisms involved and the product; some cofermentations rely on wild or mixed cultures, which can yield variable results. When well-managed, cofermentation can yield greater flavor complexity, faster acidification, or novel textures compared with monoculture processes.