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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.

（点击英国广播公司网站查看原文）

美军三明治可保鲜两年

       据英国广播公司报道，美军近日研发出世界上最尖端的三明治，可以保鲜两年。

       食品专家首先从成分着手，取材包括糖、盐、蜂蜜等，这些物质含有水分但能将其包裹，可避免潮气接触其它食材。

       为了与氧气隔绝，每个三明治都使用气封包装，并装有一小包成分为铁锉的氧气清洁剂，它能吸收周边空气，将其融于一层铁锈中。

       避开氧气和水，三明治自然能在此条件下保存两年。

(China.org.cn December 13, 2011)