How to Make Freeze Dried Food - Mountain House Freeze Dried Food
By Frank Salvo
There are several advantages to freeze drying food over other preservation methods. The freeze drying process is actually a three step process. Preparing a freeze dried meal requires only one step. You just add water.
There are many advantages of freeze drying over other traditional food preparation methods. These advantages make freeze dried food ideal for long term food storage programs.
Foods that are frozen retain their fresh flavor and nutritional content, but they also require constant, low temperature storage conditions, and most importantly electrical power. Canned and dehydrated foods are shelf-stable, but the high temperatures used in manufacturing can alter the flavor, texture and nutritional value of the food. Freeze drying comprises the best of these other processing methods. Freshness, aroma, and color are similar to frozen food, while also providing the shelf stability of dehydrated and canned food.
For different foods, the freeze drying process varies with temperature, time, pressure, and other intermediate steps. Bacterial counts are first taken of the foods. Depending on its original size, the food may next be cut into smaller pieces. For example, because thick meats do not take well to freeze drying, they must be cut into smaller chunks.
Meat and seafood are then cooked before freeze drying. Fruits and vegetables are washed first. Some vegetables such as peas and corn have to be blanched.
The food is flash frozen next by placing it on trays, the trays placed on carts, and the carts rolled into cold rooms where the temperature reaches as low as -40 F.
The carts are then wheeled from the cold room into the vacuum drying chamber. There, a process known as sublimation takes place. Sublimation of an element or compound is a transition from the solid to gas phase with no intermediate liquid stage. This is accomplished by first removing the air in the chamber with a vacuum pump. Next, the temperature is raised to 100 F.
Because the pressure in the vacuum chamber is below the point where water can simultaneously exist as a solid, liquid, and gas, (this is called the triple point), the heat causes the ice crystals to immediately change into water vapor. The water vapor is then removed from the chamber, leaving on the food behind.
At this point, the dried food will have small voids or pockets, similar to a sponge. These voids are where the ice crystals where present. At this stage, the food will absorb water much more easily when it is prepared for eating.
Next, the freeze dried food is tested for moisture content and purity. Some foods will then be broken into smaller pieces, or even grounded into a powder. The different ingredients for a meal are then blended together and the end result is packaged in airtight containers such as pouches or cans. This prevents them from absorbing moisture from the air.
In the end, freeze-dried foods have several advantages over other types of foods used in long term food storage. Freeze dried foods retain all the fresh taste and nutritional content of frozen foods. Also, unlike dehydrated foods which shrink and shrivel under the high temperature drying process, freeze dried foods maintain their original shape and texture. They also weigh less than fresh food and take much less storage space. As long as they are kept in their original packaging, these foods stay fresh longer and can be stored at room temperatures.
You'll never have to worry about mountain house freeze dried food again! Visit us on the web at Mountain House Freeze Dried Food to learn more.
Article Source: Artipot
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