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Wednesday, January 28, 2009

Dehydrating and Drying Basics

Everyone's heard of dried food. Have you ever opened a package of onion soup mix to make onion dip with sour cream? Ever eaten a raisin? A prune? Beef jerkey?

Dehydrating is the oldest way to preserve food. A long time ago, people would use salt to dry food, or place the food on rooftops any other way to be in the sun. They took the chance with insect bugs, or scavening critters, or a sudden rain that would prompt starting the drying process all over again.

These days, we have machines built specifically for dehydrating food. Food dehydrators are safe because they were created to gently pull out the water from the food. Once water is removed, it won't spoil because bacteria and mold won't grow where there isn't water. There is, however, a slight loss of some vitamins, like A and C, and it takes time to dry (anywhere from 6 to 48 hours). Besides drying fruit and vegetables, your can also dry meat, stews, cassaroles, jerky, fruit leathers, herbs and more.

Keeping the temperature below 200 degrees F is essential to drying versus cooking your food. Most electric dehydrators have regulators on them.There are several ways to dehydrate your food:
  1. SUN: To use this method, you need 3-4 sunny days of about 100 degrees each day, with no moisture. Plus you need a screen or netting to keep bugs away from your food. This process is inconsistent because you can't really assume the sun will stay hot, and you have to bring them in every evening.
  2. CAR: As we all know, cars left in the hot sun can get quite hot. We have a friend who placed trays of netting-covered food in her non-working car. She left the windows down a crack to let out the moisture. This worked very well.
  3. OVEN: Some people have succces with gas ovens, placing trays of food inside with only the pilot light on. You could also use an electric oven turned the lowest it can go, but you'd still need to keep the door open to circulate air and to not over-cook the food. However, the food doesn't end up tasting the best, and it's not energy efficient.
  4. HOMEMADE: Some people make their own. Another friend built his house to have a "drying room" - on the South side of his greenhouse. It was enclosed, with fans that circulated filtered out from outside. There were many spaces for trays (like baking racks). This is a good thing for people with the need to dehydrate huge harvests.
  5. ELECTRIC DEHYDRATORS: There are so many of these on the market, ranging in price from $40 to well over $800 each. Some are circular, some rectagular. Some can add additional layers, some have fruit leather trays, and some have temperature control. Some even rotate the trays so you won't have to. They are all energy efficient and operate at the low temperatures needed to keep nutrition in the food. Make sure the one you choose has a fan to circulate the air which will aid the drying process.
How To Dry:
  • Keep the temperatures steady. Under 110 degrees will not dry it properly and will cause the food to spoil sooner. Temps around 110 to 115 degrees F will dehydrate it enough to prevent bacteria growing on the food as it dries, while keeping it RAW. Most electric dehydrators have a set temp of around 120-140 degrees F, which is fine. Going a little higher, up to 200 degrees, will dry the food between RAW and COOK. Over 200 degrees F and the food is not only cooked, but also will cause the food to lose its nutrition and flavor.
  • Most instructions recommend turning the food about halfway or 3/4-the-way through the drying process to help get both sides.
  • Slice your vegetables, fruit, etc to be even in size. If you have a very thin slice of zucchini, and a thick chunk, they will dry at different rates. It will be easier to gauge drying times if the sizes are consistent.
  • Your food is dry when it's crisp or leathery to the touch, with no moisture. Tear it in half - if there are moisture beads at the tear, or if it just bent, it's not dry enough. Meat is a little different; it should NOT snap apart but should be leathery.

Storing Dehydrated Food:

  • When your food is appropriately dried, we place it in a baggy and place that baggy in the freezer to kill any bugs that might be on the food. After 2-3 days, we take it from the freezer, let defrost, check it for moisture, dehydrate it additionally if needed, and store the baggy in a container.
  • You need your final storage to be containers that will not allow any moisture in. Mason jar, empty-clean-dry mayonnaise or mustard jar, plastic freezer "tupperware", etc. You could also use a sealing machine or plastic freezer baggies.
  • Store fruit leather by laying the leather on plastic wrap and rolling it up. Cut to fit your storage container.
  • We place oxygen and moisture absorbers in our containers before we seal them. Never allow moisture to get into the container.
  • Store your containers in a cool, dark, dry place. Under 60 degrees F is best. If your storage container is glass or see-through, wrap it with dark construction paper. That is also a good place to put your label.
  • Label each with contents and date dehydrated/stored. Very important. Use the oldest first.

Coming soon: we'll post dehydrating information for fruits, veggies, stews, meats, fruit leathers, and more - each with it's separate post.


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