How to prepare Freeze Dried Foods
Freeze-Drying Foods Gets The Wet Out!
hearing the term 'lyophilization', or more commonly known as,
'freeze-drying', many of us think of astronauts and space travel, but
actually, it's not rocket science; it's down-to-earth science that
demonstrates how organic material exposed to low temperature within a
high-pressure atmosphere, goes through 'sublimation'. Sublimation is
when water in solid (ice) state, converts directly into its vapor (gas)
state, and is essential to the freeze-drying process; removing 98% of
moisture from food without harming or altering the food's structure.
Once re-hydrated, freeze-dried food regains its shape, color, flavor,
and texture, and most importantly, loses none of its nutritional value.
TO MAKE YOUR OWN FREEZE-DRYER YOU WILL NEED:
* A basic foam or plastic cooler. Cooler size should depend on amount
of food to be freeze-dried. Cooler MUST be full, so if using a larger
cooler, be sure to have enough food and/or ice make a full cooler, or
results won't be optimal.
* Zip-lock Type Freezer Bags
* Dry Ice
* Insulated Gloves
TO PREPARE AND FREEZE-DRY YOUR OWN FOODS:
1) Now that your freeze-dryer is complete, decide which foods to
freeze-dry. Potatoes and apples are great starters, but be
adventurous--experiment with a variety of foods. You want a freeze that
quickly evaporates maximum moisture from foods;it's critical to slice
THIN, CONSISTENTLY SIZED pieces.
2) Fill bags with sliced foods, and seal, taking care to expel air from
bag. Use a vacuum-sealer if you have one; if not, press out air
manually. Each packet should be equally filled--moderately full, but
packed loosely enough so when placed between layers of ice, the entire
bag's surface makes contact with the ice, and freezes in a consistent
3) At the last minute, and wearing gloves TO AVOID FROSTBITE, spread
generous layer of dry ice over the entire floor of cooler. Neatly
arrange food packets over the ice without overlapping bags. Alternate
food and ice so that when finished, top and bottom layers are ice.
4) Close cooler and wait 30 minutes before checking food. If bag
contents are soft or even slightly pliable when probed, then replace lid
and recheck for firmness every few minutes. Freeze-time will vary and
is dependent on volume of food being freeze-dried.
5) Once you're certain food is completely frozen, set cooler outside
with lid off, allowing dry ice to evaporate, leaving only your
freeze-dried foods behind.
6) Label bags with food name and freeze date. If food packages were
vacuum-sealed they can stay in the pantry for years; if not, they won't
last as long, and you may wish to put them in a freezer. Be aware that
freezer bags can allow air in, and that significantly decreases shelf
life. Only store food bags outside freezer if you're ABSOLUTELY 100%
POSITIVE of your bag's seal.
ADVANTAGES OF FREEZE-DRIED FOODS:
* Can store at room temperature remaining spoil-free for long periods of time.
* Extremely lightweight (98% water removed) making them easy to store and convey.
* Maintain their look, texture, taste, and nutrition even better than canned or dehydrated foods.
* Many foods, like apples, can be eaten in freeze-dried state, without needing to rehydrate first.