美国明尼苏达大学的微生物学家近期发现了一种超强天然防腐剂，能够杀灭各类细菌，使食物在常温下也能保存很久。据悉，这种防腐剂名叫“比辛”，是从一些无害细菌中自然产生的。这种防腐剂能够阻止肉、鱼、蛋和奶制品腐坏，对已开启的红酒和沙拉酱也同样有效。添加了这种天然防腐剂的食品甚至不需要放入冰箱，在常温下就可以保质数年。不过，由于蔬菜和水果的机能不同，该防腐剂不能对其起到保鲜作用。研究人员表示，这种天然防腐剂比之前的任何一种都要好，因为它不会破坏食物的营养成分，也没有任何化学成分被添加到食品当中，它只是一种天然成分。目前，研究人员已经在美国为“比辛”申请了专利。添加了“比辛”的牛奶、香肠及三明治等产品有望在三年内上市。

Fresh food could be made to last for years after scientists discovered a natural preservative capable of destroying a whole class of bacteria, including E.coli and listeria.

Fresh food could be made to last for years after scientists discovered a natural preservative capable of destroying a whole class of bacteria, including E.coli and listeria.

There would also be no need to refrigerate produce treated with the preservative, called, bisin, which is produced by harmless bacteria.

They say that foods like milk, sausages and sandwiches containing the agent could be on the shelves within three years.

Ready meals, opened wine and fresh salad dressing could also be safely consumed long after they were bought, say scientists.

Researchers at Minnesota University in the US discovered the substance from a culture of a harmless bacteria, Bifodobacterium longum, commonly found in the human gut.

It is the first naturally occurring agent identified that attacks so-called gram-negative bacteria such as E.coli, salmonella and listeria.

Dan Sullivan, an Irish microbiologist who now works at the university, told The Sunday Times: "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."

He and his team have patented the substance in the US.

Bisin is related to nisin, which attacks gram-positive bacteria, and is used in the manufacture of processed cheeses and meats. As such, it is generally recognised as safe and would not have to be pharmacologically tested.

It would not be able to prevent fruit and vegetables from rotting, however, as they decompose in a different way.

Further research is now ongoing, looking at exactly how good it is at stopping bacteria from growing.

Meanwhile, a British wholesaler has begun to make sandwiches with a two-week shelf life, by replacing all the oxygen in the plastic packaging with nitrogen and carbon dioxide.

Ray Boggiana, a food technologist who helped develop the range for Booker, which supplies convenience stores, said: "The science is not new. It's all about using a protective atmosphere in the packaging."

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(Agencies)

Vocabulary:

E.coli: 大肠杆菌

listeria: 李斯特菌（肉类、蛋类、禽类、海产品、乳制品、蔬菜等都已被证实是李斯特菌的感染源。）

Bifodobacterium longum: 长双岐杆菌

（中国日报网英语点津 Helen ）