Freeze-dried meals and ration packs: principles

In freeze-drying, the food is first frozen and then placed in a vacuum chamber. There the ice turns directly into vapour without melting first, and is drawn off. What remains is a very light, porous product that largely keeps its shape. In oxygen-tight packaging it keeps for a long time, but it needs water to prepare, which you have to carry or treat safely on site.

Retort pouches work like a tin in flexible packaging: the food is filled into the pouch, which is sealed and then heat-sterilised together with its contents. The food is fully cooked and needs neither water nor cooking. In return it is heavier than freeze-dried food, because the water is still in it.

Both kinds keep longest when stored cool and dry. Heat shortens shelf life considerably – a car boot in summer is therefore not a good long-term storage place. This entry gives no fixed shelf-life figures; the manufacturer's information applies.

Freeze-dried meals are ideal for multi-day tours with a water source, where every gram counts. For emergencies at home, where water or a way to cook might be missing, they are less suitable. There, retort pouches or tins are the better choice, because they can be eaten cold and need no extra water.

Such packs are not intended as the sole diet over a long period. They are expensive, create a lot of packaging waste and are often high in salt. A cheaper alternative is a self-assembled set of instant oats, couscous, instant mashed potato and dried soups – although it usually keeps for a shorter time.

Try different varieties in everyday life before you stock them: do you like the taste, do you tolerate them, is the portion enough, which allergens do they contain? Anyone opening a pack for the first time in an emergency often gets unpleasant surprises.

With freeze-dried meals, follow the package instructions: add the stated amount of safe, ideally boiling water, stir, seal, wait for the stated time and stir again. With cold water it takes much longer, and the food often does not become fully soft. Retort pouches can be eaten cold or warmed in hot water according to the instructions.

Count the water: the preparation water for freeze-dried meals and the extra drinking water – many ready meals are salty and make you thirsty – belong in the water stock. Storing freeze-dried food without water is one of the most common mistakes.

Flameless heaters react with water, become very hot and release flammable hydrogen in the process. They are used only according to the package instructions, well ventilated and away from open flames – never in closed vehicles, tents or small rooms. Do not touch the heater while it is reacting.

Boiling water in a soft pouch can easily tip over and cause severe scalds. So stand the pouch on firm ground or in a mug and keep children away.

Swollen, leaking, damaged or unusual-smelling pouches are not eaten – not even if the date has not yet passed. A bulge can be a sign that germs have multiplied inside.

Freeze-dried outdoor meals and retort pouches come from expedition and military catering and are widely available today. Brands, contents and portion sizes differ greatly; this entry deliberately recommends no brand.

Official preparedness guides such as Ready.gov recommend mainly food for the emergency stock that needs little or no cooking and little water, and name ready-to-eat tinned food as a basis. Ready-made packs are a sensible supplement, especially for the go bag and the car – provided they do not lie there permanently in the heat.