Gisten

Gisten is the Dutch term for yeasts, a diverse group of unicellular fungi that play a central role in fermentation and food production. Most yeasts belong to the phyla Ascomycota or Basidiomycota, with Saccharomyces cerevisiae among the best known species. Yeasts are found in many environments and are widely used in industry, science, and nutrition.

Biology and metabolism: Yeasts are typically small, about 3 to 4 micrometers in diameter, and they reproduce mainly by budding. They can grow aerobically, but many species ferment sugars to ethanol and carbon dioxide in anaerobic conditions. This fermentative metabolism underpins their use in breadmaking and alcohol production. Growth temperatures and sugar preferences vary by species, but industrial strains often thrive around 25 to 30°C.

Diversity, ecology, and health: Yeasts occur naturally on plant surfaces, fruits, nectar, and in soil. While most yeasts used commercially are safe, some fungi in the wider yeast group, such as certain Candida species, can be opportunistic pathogens in humans. The most important industrial yeasts are Saccharomyces cerevisiae (baker’s and brewer’s yeast) and its hybrid Saccharomyces pastorianus (lager yeast). Other genera encountered in fermentation include Kluyveromyces, Pichia, and Yarrowia.

Uses and applications: In baking, baker’s yeast leavens dough by producing carbon dioxide. In brewing and winemaking, yeasts ferment sugars to ethanol and contribute flavors and aromas. Nutritional yeast serves as a deactivated food supplement and provides vitamins and minerals. Yeasts also serve as model organisms in biological research and, in some cases, as probiotic strains such as Saccharomyces boulardii.

Notes: In Dutch, gisten can also be used as a verb meaning to ferment. Food-grade yeasts are generally regarded as safe under international regulatory frameworks.