/ 40 g yeast

Yeast comprises unicellular fungi of the genus Saccharomyces, most commonly Saccharomyces cerevisiae, which convert sugars into alcohol and carbon dioxide through fermentation. The organism is native to fruit skins and exists throughout nature, though commercial yeast is cultivated in controlled conditions to ensure purity and consistent performance. Yeast cells are microscopic and typically appear as light brown or beige granules or paste when processed for culinary use. The flavor varies subtly depending on the strain and fermentation conditions, ranging from slightly sweet and nutty to earthy and complex in aged cultures.

Commercial yeast for baking and brewing is available in several forms, each with distinct moisture content and viability. The primary strains used in food production have been refined over centuries of selective breeding and industrial cultivation.

Yeast serves as a leavening agent in bread-making, where it ferments dough and produces carbon dioxide gas that creates rise and aeration. It is essential in beer and wine production, where it ferments sugars into alcohol and develops characteristic flavor profiles. In baking, yeast is used to proof doughs for several hours, developing gluten structure and creating an open crumb. Beyond traditional fermentation, inactive yeast or yeast extracts (such as nutritional yeast) add umami depth to savory dishes. Proper hydration, temperature management (typically 21–27°C for baking), and timing are critical to successful fermentation.