Saturday, February 9, 2013

Freeze Dried vs. Dehydrated Food

I have been surprised to find that the majority of people I talk to don't know the difference between Freeze Dried and Dehydrated foods.  If you fall into this category, I strongly recommend you read through this post, as it will provide a great overview of both!

Dehydrated and Freeze Dried foods are similar in some ways:
- moisture is removed from the product
- product has an extended shelf life

The methods that are used to dry the foods, as well as the finished product, is where the differences come through.

Dehydrated Foods
Dehydrated Onion Slices
"Dehydrated" is a term used for all foods that have had the water removed.  Whether it be open air drying from the sun or wind (as has been done for hundreds of years), or by drying with higher temperatures for shorter periods of time; several foods lend themselves well to the dehydrating process.

Most commonly, the term dehydrated is referring to vegetables, fruits, spices, and beans, though it also includes milk, dairy, cheese, fruit, vegetable, egg and oil powders.

The end result is a lighter-weight, size reduced, shelf stable, easy to use alternative to fresh.

Because the texture and size of the food is altered during the dehydration process, some types of foods change completely (think grape to raisin).
There are other types of dehydrated foods that have smaller differences; like potatoes.

Some foods hydrate quickly and easily, while others (such as corn, peas and green beans), have to be cooked to reconstitute fully, resulting in more time and less nutrients.

The shelf life of dehydrated foods is extended greatly (7-8 years on average).

The disadvantages include the loss of nutrients, longer reconstitution times, changes in color/texture/shape/flavor, as well as the possibility of becoming bloated if too much is consumed, since it will absorb the moisture in your stomach and expand.

Freeze Dried Foods
Freeze Dried Whole Strawberries

Freeze dried foods are flash frozen, followed by a process called sublimation.
Basically, the food is frozen, and then put into a vacuum chamber where the pressure drops immediately.  This allows the frozen water in the material to sublimate, going directly from the solid phase, to the gas phase.

Freeze Dried Grape, Regular Grape, Dehydrated Grape (raisin)

The end result is an extremely light weight, low moisture replica of the original food.
As you can see from these two pictures, freeze dried foods maintain the same size, shape and color.
They also have the same flavor, and most importantly, the same nutritional value as fresh.

Freeze Dried Grape, Regular Grape, Dehydrated Grape (raisin)

Freeze dried foods have the lowest moisture content obtainable, resulting in the longest shelf stability (25-30 years).  This is the only method used to dry meat products for long term shelf life.

They reconstitute easily in hot or cold water, but can also be eaten dry, so no cooking is 'required' in preparation.

The disadvantages to freeze dried foods are that it requires special equipment; making it impossible to do at home, which results in higher costs and limited options for obtaining it.

Pro's and Con's
Both dehydrated and freeze dried foods make a great addition to any home storage system.

Benefits to Dehydrated:
- do it yourself
- cost effective
- extended shelf life (7-8 years)
- store larger amount of food in smaller amount of space
- lighter in weight

Benefits to Freeze Dried:
- lightweight
- same nutritional value as fresh
- extremely long shelf life (25-30 years)
- food resembles its fresh alternative more than any other; same size, shape, color, texture, taste, etc. 
- only method available for long term storage of meats

All in all, both have their place in my pantry.  However, I have come to really love the benefits of freeze dried over that of dehydrated.  The taste, texture, shelf life and nutritional value far exceed that of  its dehydrated alternative.  Not to mention the absolute convenience of it.  So much so, that I am even willing to fork over the extra cash for it in most cases.  Here are a list of my personal favorites of each:

My favorite Dehydrated Foods:

My favorite Freeze Dried Foods:

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