Microbial derived preservatives

Microbial natural preservatives come from a wide range of sources, including bacteria, defense bacteria, yeast, and mold, all of which can produce antibacterial substances during their growth and reproduction. However, the only microbial preservatives approved for use by the National Technical Committee for Food Additive Standardization in China are streptomycin and natamycin, which have been approved for use in over 50 countries.

Bacterial Natural Preservatives
The antibacterial substances produced by bacteria are called bacteriocins, It is a complex of skin, sugar, and fat. Dozens of bacteriocins have been found in lactic acid bacteria (including lactic acid bacteria, Streptococcus, Lactobacillus, and Leuconostoc) both domestically and internationally. Among them, nisin, also known as lactostreptomycin, is widely used. Nissin is an intramolecular ring formed by 3-4 amino acid residues and 5 thioether bridges. It has a strong inhibitory effect on various Gram positive bacteria, but is ineffective against Gram negative bacteria, yeast, and mold.

Natural Preservatives Produced By Actinomycetes

Natamycin, also known as horseradish toxin, produced by Streptomyces natalis, is a polyene macrocyclic acetic acid compound that effectively inhibits and kills toxic bacteria, yeast, and filamentous fungi, but is ineffective against bacteria and viruses. Tylosin is a macrocyclic acetic acid compound produced by streptomycin, which acts similarly to streptomycin. Polylysin produced by white chain mold is a polyphenolic substance formed by the condensation of lysine, which can inhibit Gram positive, Gram negative bacteria, yeast, but is ineffective against mold. It has good thermal stability and can be heated to 100 ℃, 100 minutes or 120 ℃, There is still an inhibitory effect on microorganisms after 20 minutes. Generally, it is used in combination with auxiliary agents such as glycine, sodium acetate, ethanol, lysozyme, etc. in products such as rice, boiled food, pickled vegetables, fish cakes, etc. The lysozyme produced by Streptomyces pyogenes can specifically dissolve Staphylococcus aureus and other food contaminating bacteria, with a wider spectrum of lysozyme than protein lysozyme.

Mould
The antibacterial substances produced by Monascus mainly act on bacteria, which are related to the polyketide pigments produced. The kojic acid produced by Aspergillus oryzae fermentation has inhibitory effects on certain bacteria and fungi. Inoculation of Salmonella casei Penicillium on the surface of dry sausages can inhibit the growth of fungi that produce fungal toxins.