COMBAT rations just got ... lovely.

Despite having started life as the Quartermaster Subsistence School in the 1920s, the US Department of Defense Combat Feeding Directorate (CFD) has to date failed its most basic task - sandwiches.

Or more precisely, sarnies that don't go soggy in the heat of battle.

"(Soldiers have) been asking for sandwiches for a long time," Julie Smith, senior food technologist with the Combat Rations Team told www.army.mil.

"Trying to come up with that technology to be able to provide the sandwich to the warfighter is the difficult part."

If the US military likes anything, it's a challenge. And when they get it right, they get it right on a big scale.

So who's ready for their two-year-old BBQ Chicken Deluxe?

media_camera A product shot of the 4-pack of Bridgford's shelf-stable barbequed beef sandwiches. Picture: Courtesy of Bridgford

The hi-tech pocket sandwich forms part of the military's First Strike Ration and it tastes... "definitely great", one soldier told the BBC.

"Most definitely the best two-year-old sandwich I've ever had," another said.

Up until now, US soldiers have had to rely on the infamous "MRE" - Meals, Ready to Eat rations.

They range from spaghetti and meatballs to vegetable omelette, but the people who have to eat them say you couldn't exactly call them "flavours".

They're also heavy. At least, heavy compared to a chicken sammich.

The First Strike Ration sarnie succeeds due to a simple combination of sugars, salt and iron filings.

The sugars and the salt are in the ingredients, acting as "humectants" - substances which retain water. That keeps the inside of the sandwich moist while depriving bacteria of one essential ingredient for survival.

A packet of iron filings in each sandwich bag acts as an "oxygen scavenger", robbing bacteria of its other essential ingredient. Trapping the oxygen in rust also prevents yeast in any mould present from thriving.

The end result is a sandwich that can be eaten up to two years after it's been packaged and exposed to heat up to 26C.

It's 50 per cent lighter than an MRE and in tests on firefighters, the CFD claims its gave them the energy to work 30 minutes longer in a day and require 30 minutes less rest.

It comes in five flavours, but the CFD's ultimate goal is a peanut butter and jelly version.

"(PB&J) doesn't make a high-quality sandwich," CFD's senior food technologist Julie Smith told army.mil.

"We're still working on that. Who wants a soggy sandwich?"

Read more than you could have ever imagined possible about survival sandwiches at www.army.mil

Originally published as Sandwich Evolved - soldiers eat two-year-old food