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The U.S. Army has developed the world's most cutting edge sandwich, one that can be served fresh for two years, BBC reported.

Food scientists started with ingredients like sugar, salt, or honey that contain moisture but also retain it, keeping it out of contact with other ingredients.

To keep oxygen away from the sandwich, each one is sealed in an air-tight package with an oxygen scavenger -- a small packet of iron filings that pulls oxygen from the ambient air and locks it up in a layer of rust.

Devoid of oxygen and water, a sandwich can last two years in the case.

（點擊英國廣播公司網站查看原文）

美軍三明治可保鮮兩年

?????? 據英國廣播公司報道，美軍近日研發出世界上最尖端的三明治，可以保鮮兩年。

?????? 食品專家首先從成分著手，取材包括糖、鹽、蜂蜜等，這些物質含有水分但能將其包裹，可避免潮氣接觸其它食材。

?????? 為了與氧氣隔絕，每個三明治都使用氣封包裝，并裝有一小包成分為鐵銼的氧氣清潔劑，它能吸收周邊空氣，將其融于一層鐵銹中。

?????? 避開氧氣和水，三明治自然能在此條件下保存兩年。

(China.org.cn December 13, 2011)