Thursday, November 4, 2010

Dehydrated Vs. Freeze Dried

Two of the most amazing food storage methods used today are dehydration and freeze drying. While they both have their applications, the average consumer doesn’t understand the difference between the two processes and where they would be used.

When foods are dehydrated, they are placed in a hot dry environment, and over time the water evaporates out of the food leaving it dry. This heat, unfortunately, leads to some vitamin loss and flavor loss. However this can be overcome by the addition of preservatives or the addition of flavor compounds like salt. Foods that are typically dehydrated are individual foods like fruit or vegetables or meat and not “compound” foods like stews or soups, etc. Dehydration is cheap and easy to use, as all it really requires is the sun.
Freeze Drying

Freeze Drying is more expensive, but the process is brilliant. A food (single foods like berries or fruit or compound foods like stews or soups) is frozen and then placed in a low pressure environment with a little heat which allows the water to “boil” or sublimate directly from a solid to a gas, leaving the food as a solid piece of food which will last indefinitely. These foods contain about 1-4% water and retain most of their flavor while requiring nothing more than hot water to be reconstituted. The poster child of freeze drying is Astronaut Ice 

Cream which is still as good as it was 40 years ago.
Both processes are still very much in use today, and should be for years to come. A good food storage can contain both dehydrated and freeze dried foods to supply a nice variety for anyone in a pinch. Dehydrated foods look like shriveled up versions of their original food (think grape vs. raisin), while freeze dried foods retain the shape of their original food, but have the texture and feel similar to Styrofoam; light and airy.


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