Levain

Levain, also known as sourdough starter, is a fermented dough containing wild yeasts and lactic acid bacteria. It is made by mixing flour and water and allowing it to ferment naturally over time, developing a complex microbial culture. This culture is then used to leaven and flavour bread.

Levain is primarily used as a natural leavening agent in bread making, contributing to a characteristic tangy flavour and chewy texture. It is favoured by artisan bakers for its flavour-enhancing properties and is found in a variety of bread products, including sourdough loaves, rolls, and some enriched breads.

Levain is not a food additive and does not have an E-number. Its use in bread making can increase the bioavailability of certain minerals and may lead to a lower glycaemic response compared to bread made with commercial yeast, according to some research. The fermentation process can also pre-digest some of the gluten, potentially making sourdough easier to digest for some individuals, though it is not suitable for those with coeliac disease. The European Food Safety Authority (EFSA) has not specifically evaluated levain as a food additive.