Now, a magic ingredient that can keep food fresh for years

The preservative could extend the food's life for several years -- and even work for opened bottles of wine and salad dressing, the researchers said.

The discovery, they said, is set to revolutionise the way people shop and can also reduce the tonnes of food waste thrown out every year, the Daily Mail reported.

According to the researchers, bisin occurs naturally in some types of harmless bacteria. It prevents the growth of lethal bacteria including E-coli, salmonella and listeria.

The substance could extend the life of a variety of everyday foods which have strict use-by dates including seafood, cheese and canned goods, they said.

In some cases these foods could last for years and may not even need to be kept in the fridge, they claimed.

The scientists, who have patented the substance, are already in talks with food manufacturers. The first products containing bisin are expected to be on the market within three years.

Dr Dan O'Sullivan, a microbiologist at the university who accidentally found bisin while examining a culture of bacteria found in human intestine, 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. It's aimed at protecting foods from a broad range of bugs that cause disease," he said.

According to the researcher, bisin will not prevent fruit and vegetables rotting as they decompose in a different way.

Sandwiches, takeaways and ready meals have now become a staple part of diet, but mass production has increased the risks of food poisoning.

Salmonella was one of the biggest culprits, accounting for around one in eight of those. Up to 500 people die from food poisoning every year in the UK alone.

Bisin is chemically related to nisin which is already used to keep processed cheese sterile and edible for decades so it does not require pharmaceutical testing.

Last month food and drink wholesaler Booker revealed it would start supplying sandwiches with a shelf-life of two weeks to convenience stores and corner shops.

The sandwich, the firm says, is designed to minimise wastage and the secret to its long life is in the ingredients, including oatmeal bread, as well as a protective atmosphere inside the packaging.

It uses a process of gas flushing in which oxygen in the packaging is replaced by CO2 and nitrogen.