How to Prepare Freeze-Dried and Dehydrated Foods

Freeze-dried foods are foods with their moisture removed through a vacuum process, in addition to sublimation of frozen moisture. When rehydrated they look similar to and taste as good as their fresh counterparts. Dehydrated foods have their moisture removed by an low-heat process such as placing items in the sun for several days and weeks. Though similar to freeze-dried foods in taste, dehydrated foods tend to take more time to rehydrate. The process for both requires some effort and planning. Some methods are expensive. Basic processing can yield lightweight, well-preserved foods to take on camping trips and to outdoor events.

Things You'll Need

  • Choice of food
  • Freezer
  • Roasting or freezer racks and pans
  • Aluminum foil
  • Knife
  • Paper towels
  • Vacuum sealer with bags
  • Oven
  • Dehydration unit
  • Meat thermometer
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Instructions

  1. Freeze Drying

    • 1

      Choose the food to be prepared. Good options for beginners include fruits, meats (cooked), fish and vegetables. Wash thoroughly, peeling or chopping if necessary. However you want your food to look when you rehydrate it, this is the way to prepare it for the freeze-dry process. After prepping, make sure the food is dry by removing excess moisture with paper towels.

    • 2

      Arrange your food items in a single layer on your roasting racks and secure with aluminum foil or rack lids, if available. Prepare for the freezer by punching holes throughout the bottom of the tins or foil at ½ to 1 inch apart. It is essential that the freezer's air circulate through the closed tins or racks. This dries the food. If you are processing something fragile like spinach or berries, use an aluminum roasting tin.

    • 3

      Set your freezer to its maximum cold setting. If you are using the freezer for other products at the same time, this may not be feasible. Just understand that the freeze-dry process may take longer.

    • 4

      Check your items in one to two weeks, at a maximum setting. Take a very small sample from the freezer and place it on the counter for 1 hour. If it changes color, there is still too much moisture in the food and it is not "finished." Secure the tin, closing firmly. Check back in subsequent weeks, again using only a small sample. Once there is no change in color your food is ready for the next step.

    • 5
      Preparing food at camp site

      Follow the manufacturer's directions on the vacuum sealer; drop the items in the bags and quickly seal them, removing all air from the food. Now you may place the dehydrated food in a refrigerator (meats) or cabinet (dried fruits) until you need it.

    • 6

      Rehydrate food by placing it in cold or boiling water, depending on the item and how you want to eat it. For instance, you may want to place chunk tuna in cold water, while you may want to place spinach in boiling water. You can also eat some dried fruits right from the vacuum bags.

    Dehydrating

    • 7

      Prepare your food as for freeze drying. Make sure the food is thoroughly washed, peeled and prepped. Dry excess moisture with paper towels.

    • 8

      Place meat or poultry first in the oven and heat it until the internal temperature, read by a meat thermometer, is 160 to 165 F. Then place the pieces of meat on the dehydration unit tray.

    • 9

      Follow the manufacturer's directions on the dehydrator unit; set the temperature for your food items. For example, fruit items will typically have a setting of 130 F. Make sure that you follow your particular unit's recommendations carefully.

    • 10

      Place the food in the dehydrator unit and dehydrate the items until no moisture appears in the center of the food. Most food items will appear leathery when fully dehydrated. Follow the manufacturer's drying times for your unit. Typically, fruit items take six to ten hours to dehydrae. Moisture-dense fruits like figs, plums and pineapple can take 24 to 48 hours in the dehydrator. Because you have preheated meat items, they will typically be completed in 10 to 12 hours.