Thursday, June 28, 2018

Freeze-Dried vs Dehydrated Food

A quick review of what they are and what’s the difference?


Dehydration:
Removes about 90-95 percent of the moisture content.

Freeze-Drying:
Removes about 98-99 percent of the moisture content.


THE DEHYDRATION PROCESS.
Modern-day dehydration isn’t that complex and can easily be done at home with a low-cost dehydrator such as the NESCO Dehydrator. Machines, like this NESCO circulate hot and dry air across the food. This removes much of the water. The moist air is then dried so that water continues to be removed. The temperatures are high enough to remove water but not high enough to cook the food. Dehydrated food is usually withered and harder.


THE FREEZE-DRYING PROCESS.
The freeze-drying process is a relatively modern preservation process. Freeze-drying is a fairly simple process but isn’t something you can do at home without high-tech machinery.

The food is placed on large racks inside of a vacuum chamber. The temperature is lowered to below freezing and then slowly raised. The water in the food moves from a solid state to a gaseous state - maintaining the structure of the food and keeping the nutritional value.

Freeze-drying can be done at home with a machine like the Harvest Right Freeze-Dryer. This machine is expensive, depending on the model size will cost $2,000 - $3,000.


The Main Difference between the process’ is Moisture Content.
The objective of food preservation is to remove the moisture so that the food doesn’t decompose, grow mold, etc.

Shelf Life:
The moisture removal has a direct impact on the shelf life. Most dehydrated products like dried fruits, vegetables, powders, and TVP; have a shelf life of about 15-20 years. However, dehydrated items like honey, salt, sugar, hard wheat, and oats have a 30-year shelf life - sometimes longer. Freeze-dried foods will have a longer average shelf life. Freeze-dried fruits, vegetables, just-add-water meals and real meats will have a 25-30-year shelf life.

Cooking:
Dehydrated foods will require cooking. Many times, they will also require some type of seasoning. This means that you’ll need to spend time boiling the product in hot water and letting it cook. The preparation time for dehydrated products can take anywhere from 15 minutes to 4 hours depending.

However, with freeze-dried foods, you just need to add water. Adding either hot water or cold water will get the job done depending on what you’re eating. Freeze-dried foods will usually be ready to eat in less than 5 minutes.

Cost:
Obviously, the cost of food storage will depend on what you're buying. But usually, dehydrated foods are going to be cheaper than freeze-dried. Freeze-dried and dehydrated foods offer different benefits that might be worth the cost. However, if you're on a tight budget, dehydrated foods are the way to go.


Ideally, all of your food storage would be stored at a temperature of 60 degrees or lower.

NESCO Dehydrator Link:

Freeze-Dryer Link:

General Info Source Link:



5 comments:

  1. out here in the god awful hot as hell desert we make racks out of door screen and wood slats and make jerky and fruit roll ups on the roof, usually in one afternoon. I reckon folks with humidity would need a fancy gizmo to dry out there stuff. Hell, I'm about half dehydrated most of the time! :-)

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  2. Mike, another great stop and makes you think post. Let me toss in a wrench in your well oiled post. Vacuumed sealed. I know it take the air out of a package, but do you need to VS your dry food to make it last longer yet??

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    1. Rob, I assume you’re talking about dry foods like beans, grains, pasta, corn meal, flour, etc. and the answer is, yes!

      If you buy them in bulk like 25lb or 50lb bags and can’t use all of it in a year then it’s a good idea to repackage the big bags into smaller amounts that you’ll likely use in a year and Vacuum Seal them. It’s cheap insurance that you will have safe food available when you need it.

      The vacuum sealer pump reduces the volume of air but not all of it that still contains oxygen and moisture. The two things mold spores and bugs need to grow and spoil or rot the food in the sealed bag. Mylar with oxygen absorbers inside continue to work until all the oxygen is consumed, this is the best way.

      If your plans are storing the food long term like 5 -20+ years then repackage it in Mylar Bags with oxygen absorbers.

      Hope this helps,
      Mike

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  3. Because I'm pretty much wedded to sheltering in place, I don't have to give a lot of thought to weight on food storage. The vast majority of mine is canned, or is packed in nitrogen flushed mylar bags, in food pails. I do have some of the freeze dried food , just in case, but not a lot of it.

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    1. That's about my plan also. The only way I'll leave my home to the sub-humans is because of a hurricane with storm surges. I'll go underwater if we have a 5-6 foot surge.
      I seem to regularly re-visit my food storage for practicality. I'm now focused on stocking ingredients to make 'comfort meals' for the bad times.

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