The preservative, called bisin, could extend the food’s life for several years – and even work for opened bottles of wine and salad dressing…

Bisin occurs naturally in some types of harmless bacteria. It prevents the growth of lethal bacteria including E-coli, salmonella and listeria…

Dr Dan O’Sullivan, an Irish microbiologist who works at the university, made the discovery by accident while examining a culture of bacteria found in the human intestine.

He said: ‘It seems to be much better than anything which has gone before. It doesn’t compromise nutrient quality – we are not adding a chemical, we are adding a natural ingredient.