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12.04.02, 01:16
The World's No.1 Science & Technology News Service
US military creates indestructible sandwich
19:00 10 April 02
Exclusive from New Scientist Print Edition
First came the atom bomb, the stealth bomber and the airborne laser. Now comes
the US military's latest fearsome weapon: the indestructible sandwich.
Capable of surviving airdrops, rough handling and extreme climates, and just
about anything except a GI's jaws, the new "pocket" sandwich is designed to
stay "fresh" for up to three years at 26 °C (about the temperature of a warm
summer's day), or for six months at 38 °C (just over body temperature).
Photo: M Tama/Getty Images
For years the US army has wanted to supplement its standard battlefield
rations, called "Meal, Ready-to-Eat" (MRE), with something that can be eaten on
the move. Although MREs already contain ingredients that could be made into
sandwiches, these have to be pasteurised and stored in separate pouches, and
the soldiers need to make the sandwiches themselves.
"The water activity of the different sandwich components needs to complement
each other," explains Michelle Richardson, project officer at the US Army
Soldier Systems Center in Natick, Massachusetts. "If the water activity of the
meat is too high you might get soggy bread."
Pocket pizzas
To tackle the problem, researchers at Natick used fillings such as pepperoni
and chicken to which they added substances called humectants, which stop water
leaking out. The humectants not only prevent water from the fillings soaking
into the bread, but also limit the amount of moisture available for bacterial
growth.
The sandwiches are then sealed, without pasteurisation, in laminated plastic
pouches that also include sachets of oxygen-scavenging chemicals. A lack of
oxygen helps prevent the growth of yeast, mould and bacteria.
Soldiers who tried the pepperoni and barbecue-chicken pocket sandwiches have
found them "acceptable". They are now planning to extend the menu to pocket
pizzas, as well as cream-filled bagels, breakfast burritos and even peanut-
butter sandwiches.
The pocket sandwiches won't see action until 2004. But like dehydrated egg,
freeze-dried coffee and processed cheese - all originally developed by the
military - the long-life sandwich will probably find its way into grocery
stores.
Duncan Graham-Rowe
