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Dec. 08, 2011

Science Keeps Sandwich Fresh for Two Years

by Zach Lynn

By Zach Lynn, Carleton College

One of the US Army's New SandwichesSince 1966, the US Army has been providing its troops in the field with Meals Ready to Eat or MREs. MREs are "completely self-contained meals that provide all the nutrition a solider-on-the-go needs to sustain him/herself." As of this year, there are 24 different entrees including options like chili and cheese tortellini. The science that goes into producing these meals is quite impressive.

MREs must be able to withstand parachute drops of 1,250ft and non-parachute drops of nearly 100ft. MREs are designed to stay fresh for years below 81 degrees Fahrenheit and short periods of time at extreme temperatures. They even contain a "flameless ration heater", which releases energy when exposed to water, allowing soldiers to enjoy hot meals. MREs contain drink mixes and other dehydrated foods that are often fortified with nutrients. Unfortunately MREs have earned more than a few nasty nicknames due to their sub-par taste. Among the more clever are Meals Rejected by Everyone and Materials Resembling Edibles.

In response to the criticisms of traditional MREs the US army has released a series of sandwiches that are palatable and stay fresh for up to 2 years. These sandwiches contain ingredients like jam or honey that retain moisture with humectants. Humectants, like sugar in the case of jam, bind water allowing food to retain moisture. Since the moisture is locked away, it is not accessible to bacteria and it won't seep into the bread. These sandwiches are sealed in a package with an oxygen scavenger, a small packet of iron shavings. The iron shavings deplete the oxygen in the package as they rust (and become iron oxide).

The sandwiches have received good reviews as well. Watch this video to see for yourself.

_______________________
Zach first discovered his passion for science as a high school student at Trinity School in New York City. He now attends Carleton College, where he plans on majoring in Physics. His interests in science include high energy physics, medicine, and technology.

About Zach Lynn

The views expressed are those of the author and are not necessarily those of Science Friday.

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