Riboflavin (Vitamin B2)

How it's made

Made by fermentation of yeasts/fungi, or synthesised.

Riboflavin is vitamin B2, used as a food colour to provide a natural yellow to orange-yellow shade in products such as desserts, dairy products and cereals, while also fortifying them with the vitamin. The colour and the nutrient are the same molecule.

Most riboflavin for food use is now made by fermentation. Microorganisms — certain bacteria, yeasts or fungi that naturally overproduce riboflavin — are grown on a sugar-based feedstock in large fermenters, and they secrete the vitamin, which is then harvested from the broth. This biological route has largely replaced the older, more complex chemical synthesis.

The riboflavin is separated from the fermentation liquid, purified and crystallised into a yellow-orange powder. Because pure riboflavin does not dissolve easily in water, a more soluble form (riboflavin-5'-phosphate) is sometimes used where a clear solution is needed, but both provide the same vitamin and colour.