Argon keeps chips and lettuce crisp

A method used to protect valuable treasures, such as the Declaration of Independence, now preserves everyday grocery items.

To guard food from oxygen-induced spoilage, producers often blow pure nitrogen into packages to replace air, which is about 21 percent oxygen and 78 percent nitrogen. Typically, it takes about eight volumes of nitrogen to blow just one volume of air out of a package, says Kevin C. Spencer, a consultant who advised the British grocery chain Safeway Stores. Even then, 5 to 6 percent of a package’s gas remains oxygen, he says.

Spencer has developed a way to replace nitrogen in packaging machines with argon, a gas that museums use to seal in their treasures. Much heavier than nitrogen, argon “pours like water,” says Spencer. It replaces air almost completely and requires only two volumes to remove one volume of air.

Microbial testing has found that argon packaging improves the shelf life of foods including salads, processed meats, and wines. Panels of tasters have indicated that argon makes foods taste fresher longer than nitrogen does, says Spencer.

Argon costs 4 to 5 times as much as nitrogen. However, the new system–now used in Britain–is more efficient overall.

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