Yeast

Yeast is a single-celled microorganism, a type of fungus. It is naturally present on fruit skins and in the air. For food production, specific strains are cultivated on nutrient-rich media, often derived from molasses or grain, and then dried or processed into a paste.

Yeast is primarily used as a leavening agent in baking, producing carbon dioxide gas that makes bread and other doughs rise. It also contributes to the characteristic flavour and aroma of baked goods and fermented products like beer and wine. Some yeast extracts are used as flavour enhancers.

Yeast is not considered a food additive in the UK when used for leavening or flavouring in traditional foods like bread. The Register of Food Additive Authorisations does not list yeast itself as an additive. It is a source of B vitamins and protein. Some people may experience digestive discomfort from consuming large amounts of yeast, though this is not typically associated with normal food intake.