Natamycin (Pimaricin)
What it does
Antifungal surface treatment (cheese, sausage).
How it's made
Produced by bacterial fermentation.
Natamycin (pimaricin) is a natural preservative that acts specifically against moulds and yeasts (not bacteria), used mainly as a surface treatment on the rind of cheeses and on dried, cured sausages to stop mould growing on the outside. It is an antifungal compound made by bacteria.
It is produced by fermentation using the bacterium Streptomyces natalensis. The bacterium is grown in fermenters, and it produces natamycin, which is then recovered from the fermentation broth, purified and crystallised into a fine powder.
Because it works only at the surface and is very effective against moulds at low levels, it is applied as a coating or dip on cheese and sausage exteriors rather than mixed throughout the food. Its use is regulated and limited to these surface applications, where it keeps the outside of the product mould-free without affecting the interior.
Possible reactions
Generally safe; surface use only.