Natamycin
The short version
A polyene antifungal antibiotic — used on cheese rinds and dried sausage surfaces to inhibit mold.
It's widely considered safe at the amounts used in food, so we mark it green. The Safety section below has the details.
Where it comes from
Produced by fermentation of Streptomyces natalensis, a soil bacterium first isolated in Natal, South Africa, in 1955. The same fermentation also yields related polyene antibiotics. Adopted as a food preservative from the 1960s.
How it's used
Applied to cheese rinds (dipping, spraying, or in coating wax), dried sausage casings, and the surface of some yogurts to prevent mold spoilage. Surface application only — natamycin does not migrate significantly into the food interior. Typical use 0.5–2 mg/dm² surface.
Safety profile
ADI of 0.3 mg/kg body weight. Generally considered safe at surface-use levels. Concerns about cross-resistance with medical antifungal use have prompted JECFA to recommend monitoring.
Physical & chemical properties
Yellow-white crystalline powder, very poorly soluble in water and oils — a property that contributes to its surface-only action. Binds to ergosterol in fungal cell membranes.
Regulation worldwide
Permitted in the EU and US for specific surface treatments. Maximum residue limits apply.
Educational information only. Not medical or dietary advice.