Picnics and packed school lunches may never be the same again, thanks to the latest breakthrough by military science -- the non-soggy sandwich.

Spurred on by rather unappetizing U.S. battlefield food known as Meals Ready to Eat, scientists at the Army Soldier Systems Center in Massachusetts have devised a vacuum-sealed sandwich that stays edible for up to three years.

"The water activity of the different sandwich components needs to complement each other," project officer Michelle Richardson told New Scientist magazine. "If the water activity of the meat is too high you might get soggy bread."

Using an array of chemicals to seal the meat and inhibit bacterial growth, the scientists already have produced pepperoni and barbecue chicken indestructible sandwiches, which have been given a cautious welcome by soldiers who agreed to try them.

Inspired by their apparent breakthrough, the scientists are now experimenting with pizzas, bagels, burritos and even the staple peanut butter sandwich.