Freeze-dry process – optimum preservation without water!
Well before the invention of refrigerators and freezers, people preserved their food for future use. We can safely presume that drying food items is the oldest of all preservation methods. Fresh foods, such as fruits, were dried in the sun and were thus available throughout the winter and beyond. The drying process kept the food in edible condition, as water is not only the basis for life, but also for decay. The water found in food contains bacteria, fungi and/or highly chemically active substances such as enzymes, which cause food to perish. These processes of disintegration rely on water, similar to the processes in a living cell.
The drying process is maximised and accelerated by exposing the food items to heat. Nowadays, modern technologies, such as the freeze-drying process, which is also known as lyophilisation, cryodesiccation or vacuum evaporation, ensure an extremely long shelf life. Many food items are subjected to these preservation methods and we also use these methods in preparing our Emergency Food products.
Coffee powder or packet soups are good examples of daily used products for which freeze-drying enables a longer shelf life. When hot water is added, the original form is quickly re-established and the beverage or food is ready for consumption.
How does freeze-drying work, though?
Food items which undergo the freeze-drying process are subject to strict controls and official supervision guaranteeing the use of only the highest quality products. The freeze-drying process consists of different steps:
Step 1: To preserve colour, taste and nutritional value, fresh or cooked dishes are snap frozen.
Step 2: While frozen, the products are dried by inducing extreme negative pressure conditions, almost creating a vacuum.
Step 3: The escaping condensation settles on an even colder chilling surface in the vacuum chamber. This condenser also assures that the air in the freeze-dry apparatus remains dry. In an extremely dry environment, water contained in the ice sublimates directly from the solid phase to the gas phase. This sublimation process, however, occurs very slowly, much slower than the evaporation of boiling water. Freeze-drying reduces the water contained in food items to a very small percentage.
Step 4: The food items and meals are then ready for packaging in air and water-tight cans. While the cans are being filled, the oxygen contained inside is replaced by nitrogen. Once the cans are sealed, the high quality of the food inside is guaranteed over a long period of time.
The process of decay is delayed by several years without requiring additional chilling or chemical treatments.
Quick and easy reverse process
After opening the cans, only hot or cold water must be added to return the food items to their original state. The food is ready to be eaten in no time without compromising the quality of its taste or its nutritious value.
Why emergency food?
Almost daily, we read in the media about accidents and disasters. Once the emergency has occurred, it will be too late to take any extensive precautions to control the damage. But appropriate planning will enable you to be prepared to face emergency situations. Our specially assembled Emergency Food packs have been designed to support you in this effort.
The greatest enemy of dehydrated or freeze-dried foods is moisture and oxygen. For long-term storage, foods must be packaged in solid containers with minimum moisture and oxygen contents. The purpose of packaging under a nitrogen atmosphere is to prevent oxidation of certain components contained in the food.
Food dehydration is the oldest method of increasing the shelf life of foods. For millennia, humanity has known that freshly harvested foods will not be spoiled if they are sun-cured. Such dehydrated foods used to be vital for survival during the wintertime, when food supplies were scarce. Today, state-of-the-art technologies offer new and more advanced approaches to preserving foods.