Natamycin

Natamycin (also known as pimaricin) is a natural antifungal compound produced by the soil bacterium Streptomyces natalensis. It acts against moulds and yeasts by binding to ergosterol in fungal cell membranes, disrupting their integrity. Its food use is restricted to surface application only: it is applied to the rind or casing of hard and semi-hard cheeses and the surface of dried and cured sausages to prevent mould growth during storage and maturation.

JECFA's ADI is 0.3 mg per kilogram body weight per day, established in 1976. Natamycin is poorly absorbed from the gastrointestinal tract and is rapidly broken down. At the concentrations present on cheese rinds and sausage casings, consumer exposure is minimal — particularly since most consumers do not eat these surfaces. The low ADI reflects precautionary restriction rather than evidence of harm at dietary levels.

Natamycin is approved in the EU (surface use only), US (GRAS for surface application), Australia, and many global markets. The EU requires it to be declared as "natamycin (E235)" on the label. Importantly, the EU prohibits its use in cheese or sausage interiors, only on external surfaces. Natamycin is clinically used as an antifungal drug, but its use as a food preservative does not contribute meaningfully to antifungal resistance in human pathogens due to its distinct mechanism and food-surface-only application.