Nisin
What it does
Natural antimicrobial (cheese).
How it's made
Produced by bacterial fermentation (Lactococcus).
Nisin is a natural preservative — an antimicrobial peptide (a small protein) produced by a bacterium — used to prevent the growth of certain harmful and spoilage bacteria, particularly in cheese, processed cheese, canned foods and some dairy products. It is effective against bacteria that other preservatives struggle with.
It is produced by fermentation using the bacterium Lactococcus lactis, the same kind of lactic-acid bacterium used in dairy fermentation. The bacterium is grown on a suitable medium (often milk-based) in fermenters, and as it grows it secretes nisin; the peptide is then recovered from the broth and concentrated.
The nisin is purified and standardised for its antibacterial activity, and supplied as a preparation for food use. Because it is a peptide made by a food-grade bacterium and is broken down like other proteins during digestion, it is a well-established natural preservative, used in small, regulated amounts especially in cheese products.
Possible reactions
Generally well tolerated.