If you have ever felt guilty about throwing away food because it went bad, there is some good news. Soon there won't be any need to even refrigerate products like milk or sausages and fresh food could be made to last for years.

U.S. scientists have discovered a naturally occurring agent which destroys bacteria that causes meat, fish, eggs and dairy products to decompose.

Researchers at the University of Minnesota reported the discovery of a natural preservative called Bisin, which is produced by some types of harmless bacteria. Besides preventing the rotting of food, Bisin also prevents the growth of lethal bacteria such as E.coli, salmonella and listeria.

Scientists feel that the discovery could mean that products like ready meals, opened wine and fresh salad dressing could be safely consumed long after they are bought. In some cases Bisin could extend the food's life by several years.

Everyday foods with shorter shelf life like canned goods, seafood, cheese and sandwiches could stay fresher for much longer.

This would lead to a massive reduction in the amount of food wasted and thrown every year.

Bisin was discovered by Dr Dan O'Sullivan, an Irish microbiologist who works at the university. Sullivan stumbled upon the discovery while examining a culture of bacteria, Bifodobacterium longum, commonly found in the human intestine, reports the Daily Mail.

"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," Sullivan told The Sunday Times.

He and his team have patented the substance and the first products containing Bisin are expected to arrive in the market in three years.

Bisin would not prevent fruits and vegetables from rotting as they decompose in a different way.

Bisin is chemically related to nisin, a polycyclic antibacterial peptide with 34 amino acid residues used as a food preservative. Nisin is used to manufacture processed cheese and meats. It is generally recognized as safe and would not have to undergo pharmaceutical testing.