The US Military has perfected 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)…
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.
(Thanks, Starchy!)