What is nisin (E234)? #
Nisin (E234) is a polycyclic antibacterial peptide — a class I bacteriocin, or lantibiotic — produced by fermentation of Lactococcus lactis. It consists of 34 amino acids and is used as a food preservative against Gram-positive spoilage and pathogenic bacteria. It is obtained by culturing the organism rather than by chemical synthesis.
The application data sheet reviewed for this page lists CAS 1414-45-5 and INS 234. It is a peptide, not a chemical preservative, and is digested into amino acids in the human gut.
Which microorganisms does nisin target? #
Nisin is active mainly against Gram-positive bacteria, including spore-forming Bacillus and Clostridium species, lactic acid bacteria and Listeria monocytogenes. It is generally ineffective against Gram-negative bacteria because their outer membrane protects them, and it is not an antifungal, so it is not used to control yeasts or moulds.
Where both fungal and bacterial spoilage are concerns, natamycin and nisin are often evaluated as complementary rather than competing options.
How does pH affect nisin performance? #
Nisin is most soluble and most stable in acidic conditions and loses stability as pH rises toward neutral and alkaline. Its heat tolerance is also better at low pH. Formulation pH is therefore one of the first variables to check when evaluating nisin for a product.
Published data show markedly better solubility and heat retention under acidic conditions; exact limits belong in the supplier's technical data sheet.
What dosage of nisin is typically used in food? #
The application data reviewed gives recommended nisin dosages from 0.01 g/kg in post-fermentation beer up to 0.5 g/kg in ripened cheese and heat-treated processed meat, with most categories between 0.05 and 0.3 g/kg. These are starting points for trials, not formulation instructions or legal limits.
Transcribed from the supplied data sheet. One category was omitted because the value in the source was unclear; it has not been guessed. Always check the maximum permitted level in the destination market and validate by challenge testing.
What minimum inhibitory concentrations are reported for nisin? #
The same data reports MIC values of 2-5 mg/kg for lactic acid bacteria, 10-20 mg/kg for Listeria monocytogenes and 30-50 mg/kg for Clostridium botulinum. MIC is measured under defined laboratory conditions and is not the same as a permitted use level in a finished food.
MIC values describe in-vitro sensitivity under test conditions; they should not be read as a dosage recommendation.
What acceptance criteria apply to nisin? #
The nisin certificate reviewed specifies a potency of at least 900 IU/mg, loss on drying not more than 3.0%, sodium chloride at least 50%, lead not more than 1 mg/kg and a total aerobic microbial count not more than 10 CFU/g, tested against GB 1886.231.
Potency in IU/mg is the field that distinguishes nisin grades; a product name alone does not fix it. The same certificate also requires E. coli and Salmonella to be absent in 25 g.
What should a buyer confirm before specifying nisin? #
Confirm potency in International Units per gram, the grade and carrier, permitted use levels in the destination market, and the documentation available. Nisin is sold in different potencies and formulations, so a product name alone does not define what is being purchased.
Available potencies, carriers and forms are confirmed against a specific enquiry and the current technical data sheet.