Precision fermentation

Precision fermentation uses microbes, usually genetically modified, to make one particular molecule, which is then purified out of the brew. Insulin and rennet are the best-known examples: fermentation-made chymosin (the active part of rennet) is used in most US cheese (Wikipedia: Chymosin).

The same approach now makes dairy proteins without cows: whey protein (beta-lactoglobulin) and casein, the main protein in milk and cheese. Companies including Perfect Day, Remilk, Vivici and New Culture are bringing them to market. Several have been cleared in the US since 2020, and Remilk’s milk went on sale in Israel in 2025 (Times of Israel); no precision-fermented animal protein has yet been approved in the EU or the UK (FoodNavigator).

Why we aren’t working on it ourselves

Precision fermentation is a great fit for well-equipped companies making high-value ingredients. For small, open source production it is harder: separating one protein from the brew adds cost and complexity, the microbes are usually fed sugar, and custom strains are rarely shared. Open science projects such as Real Vegan Cheese and Open Insulin have shown it can be done in the open, and we’d love to see more.