NISIN

Nisin is used as a food preservative. Nisin, is effective against a wide range of Gram-positive bacteria, both as vegetative cells and as spores.

Nisaplin is comercially produced food preservative. Its composition is

Nisin - 2.5%

Sodium Chloride - 77.5%

Protein - 12%

Carbohydrate - 6%

Moisture - 2%

It is an inhibitory polycyclic peptide with 34 amino acid residues

It contains the uncommon amino acids

lanthionine , methyllanthionine , dehydroalanine , dehydro-amino-butyric acid.

These special amino acids are synthesized by posttranslational modifications. (In these reactions a ribosomally synthesized 57-mer is converted to the final peptide.) The unsaturated amino acids originate from serine and threonine

Nisin is most stable in acid conditions.

Nisin is soluble in aqueous environments.

Some loss of activity is expected when nisin is used in heat-processed

foods.

Nisin is produced by fermentation using the bacterium Lactococcus lactis a bacterium which occurs naturally in milk.

Commercially it is obtained from natural substrates including milk and is not chemically synthesized.

It is used in processed cheese production to extend shelf life by suppressing gram-positive spoilage and pathogenic bacteria

There are many other applications of this preservative in food and beverage production

Due to its highly selective spectrum of activity it is also employed as a selective agent in microbiological media for the isolation of gram-negative bacteria, yeast and moulds

Subtilin and Epidermin are related to Nisin, all members of a class of molecules called lantibiotics. As a food additive, nisin has E number E234

Uses

Nisin was first introduced commercially as a food preservative in the UK approximately 30 years ago. First established use was as a preservative in processed cheese products and since then numerous other applications in foods and beverages have been identified. It is currently recognised as a safe food preservative in approximately 50 countries. The established uses of nisin as a preservative in processed cheese, various pasteurised dairy products, and canned vegetables will be briefly reviewed.

More recent applications of nisin include its use as a preservative in high moisture, hot baked flour products (crumpets) and pasteurised liquid egg. Renewed interest is evident in the use of nisin in natural cheese production. Considerable research has been carried out on the antilisterial properties of nisin in foods and a number of applications have been proposed.

Uses of nisin to control spoilage by lactic acid bacteria have been identified in beer, wine, alcohol production and low pH foods such as salad dressings.

Further developments of nisin are likely to include synergistic action of nisin with chelators and other bacteriocins, and its use as an adjunct in novel food processing technology such as higher pressure sterilisation and electroporation.

Production of highly purified nisin preparations and enhancement by chelators has led to interest in the use of nisin for human ulcer therapy, and mastitis control in cattle.

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