Extending the shelf life of foods with a lactic acid solution

The production of cheese results in large amounts of the side stream whey: about 10 L of milk is used to make 1 kg of cheese, leaving about 9 L of whey leftover. Now scientists have discovered a way to make valuable use of this by-product from cheese production by creating a solution that can extend the shelf life of certain food products.

Researchers at the National Food Institute, Technical University of Denmark have generated a lactic acid bacterium that secretes a food-grade preservative — antimicrobial peptide nisin — when grown on dairy waste.

Food-grade preservative nisin is approved for use in a number of foods, where it can prevent the growth of certain spoilage microorganisms as well as microorganisms that can make consumers unwell. For example, it can inhibit spore germination in canned soups and prevent late-blowing defects in cheeses — without affecting its flavour.

In theory, nisin could even be added to fresh milk to extend its shelf life. However, different countries have different rules stating what types of products nisin may be added to and in what amounts. 

Many dairies are already turning a profit by extracting protein and lactose from the many tonnes of whey they generate, which they use, for example, in infant formula and sports nutrition. What is left behind from this can still be used to produce nisin.

In addition to ensuring better resource utilisation, there may be a financial gain from producing nisin as most commercially available nisin products contain 2.5% nisin and cost approximately $62/kg.

The work related to isolating the nisin-secreting lactic acid bacteria has been described in further detail in a scientific article in the Journal of Agricultural and Food Chemistry.

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