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美國明尼蘇達大學的微生物學家近期發現了一種超強天然防腐劑，能夠殺滅各類細菌，使食物在常溫下也能保存很久。據悉，這種防腐劑名叫“比辛”，是從一些無害細菌中自然產生的。這種防腐劑能夠阻止肉、魚、蛋和奶制品腐壞，對已開啟的紅酒和沙拉醬也同樣有效。添加了這種天然防腐劑的食品甚至不需要放入冰箱，在常溫下就可以保質數年。不過，由于蔬菜和水果的機能不同，該防腐劑不能對其起到保鮮作用。研究人員表示，這種天然防腐劑比之前的任何一種都要好，因為它不會破壞食物的營養成分，也沒有任何化學成分被添加到食品當中，它只是一種天然成分。目前，研究人員已經在美國為“比辛”申請了專利。添加了“比辛”的牛奶、香腸及三明治等產品有望在三年內上市。

?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: 大腸桿菌

listeria: 李斯特菌（肉類、蛋類、禽類、海產品、乳制品、蔬菜等都已被證實是李斯特菌的感染源。）

Bifodobacterium longum: 長雙岐桿菌

（中國日報網英語點津 Helen ）