Rice koji

Rice koji is a traditional Japanese ingredient made by fermenting cooked rice with *Aspergillus oryzae*, a mould. This process breaks down the rice starches into sugars and proteins into amino acids, creating a unique flavour and aroma. It is the foundation for many fermented foods like soy sauce, miso, and sake.

In UK packaged foods, rice koji is primarily used as a flavour enhancer and tenderiser, particularly in meat products and meat analogues. The enzymes in koji break down proteins and fats, contributing to a richer, umami flavour profile and a more tender texture. It is often found in marinades, sauces, and ready-to-eat meals.

Rice koji is not typically considered a food additive in the UK and therefore does not have an E-number or require authorisation on the Register of Food Additive Authorisations. Its use is primarily for its flavour and enzymatic properties. As a fermented food ingredient, it contains various compounds produced during fermentation, including amino acids and sugars. Evidence on specific health impacts at typical consumption levels is limited, and it is not associated with major controversies.