GENERAL DEHYDRATING INFO

From campers point of view dehydrating has two very important benefits, reduction of weight, and improved storage life without significant loss in nutritional values or change of taste. Weight reduction by dehydrating varies. For example, frozen peas and zucchini lose approximately 50% and 96% of their weight by dehydrating, respectively. It can be pretty safely said that one can expect an average loss of 70% in weight of the camping food by dehydrating.

Estimated weigh reduction of some dried food items.

MATERIAL FRESH WEIGHT g DRY WEIGHT g REDUCTION %
Carrots 100 (3.5 oz) 10 (1/3 oz) 90
Potatoes 100 (3.5 oz) 20 (2/3 oz) 80
Ground beef 100 (3.5 oz) 32 (1 oz) 68
Other meat 100 (3.5 oz) 40 (1.3 oz) 60
Mushrooms 100 (3.5 oz) 10 (1/3 oz) 90
Onions/Leek 100 (3.5 oz) 10 (1/3 oz) 90
Corn (frozen) 100 (3.5 oz) 35 (1.1 oz) 65
Pea soup (canned/fresh) 100/100 (3.5 oz) 27/15 (1 oz/1/2 oz) 73/85
Cauliflower 100 (3.5 oz) 10 (1/3 oz) 90
Zucchini 100 (3.5 oz) 6 (1/5 oz) 94
Blue cheese 100 (3.5 oz) 60 (2 oz) 40

 

Even though opportunity to carry weeks worth of food in the backpack is very nice, real benefit of dehydrating comes from improved storage life. Campers and hikers rarely starve because they were not able to carry enough food, whereas spoilage of the food they are happily carrying, quite often has serious consequences. A healthy person can stay functional for days, if not weeks without food, and, few extreme adventurers aside, hikers usually are not further than few days walk away from civilization, or at least a place where they are able to draw attention of potential rescuers.

Food poisoning is another story. (Link to bacteria info here) Some bacterial toxins can kill a person almost straight away, and many others can make him/her ill enough to starve next to a backpack full of food. Probably the best way to avoid food poisoning on a camping trip is to use properly dehydrated and stored food, and to make sure that the water used for food preparation and drinking is clean.

Bacteria are everywhere, and only things they are waiting for to blossom are suitable temperature, some nutrients, and enough moisture. So,

nutrients + suitable temperature + bacteria + moisture = disaster.

To prevent bacterial growth, at least one part of the equation has to be eliminated.

Removing nutrients could be done by throwing all the food stuff away, which, for obvious reasons, is out of the question.

Next thing to consider is the temperature. In a winter time above the arctic circle the food can be kept frozen, but in most of the hiking or camping situations temperature is close to optimal for bacterial growth, and there is practically nothing a backpacker can do about it.

Also without an autoclave or a pressure-canner, it is not possible to destroy all of bacteria from food. Therefore one must settle with an effort to minimize bacterial contamination and use only the freshest and cleanest materials in an hygienic environment.

Due to the fact that the first three parts of the equation cannot be totally eliminated, extra attention must be given to the dehydrating procedure:

1. The dehydrator must be kept clean.

Any left over mess from previous dehydrating sessions works as a culture dish for bacteria, mold, yeast etc., and the new fresh round of moist material will act as an energy drink, spiked with amphetamine, for the present bacteria.

2. The surrounding conditions.

It may be OK to dehydrate, for example, mushrooms in dry Arizona desert using only an air blower without heating, or using a heater, set on 40 C degrees in room temperature environment, but trying to do either one during a hot humid spell in Louisiana, where the blower would act as humidity feeder, would be suicidal. I would not have mentioned this otherwise, but I happened to find, on a commercial cooking site, some jerky instructions (excellent spice cocktail btw) with an advice to use only an air blower without any extra heating. Comments about the instructions were generally positive, but there was one commenter who wrote that his entire family got sick after eating that horrible jerky. It is of course possible that the poor guy used some contaminated meat to begin with, but I strongly suspect that he made his jerky in some hot and humid place without understanding the basics of dehydrating mechanism.

3. Storage.

I live pretty close to the arctic circle and the climate here is generally cool and dry. I store all my fruits, veggies, spices and mushrooms in either carefully closed zip lock bags or in glass jars, protected from the light, in room temperature. (Some of my friends successfully store their mushrooms in paper bags). The oldest material I have used has been in a kitchen closet for over a year. I try to dehydrate meat, fish, and any other fat containing product right before my next hike, and if I have to store the material for a longer period of time, I put it into the freezer in a zip lock bag.

Common sense is a valuable asset when choosing the right storage method.

4. Rehydration.

All of my outdoor cooking sessions begin with boiling a pot full of water. Next step is to pour the boiling water on top of the material to be rehydrated. There are two reasons to why I do that. First, hotter the water, faster the rehydration, and second, if, and when there are any hostile bacteria in my dried food, they don’t begin to grow under the boiling water. I never ever soak my dried goodies in cold water. Even though there are lots of internet pages with recommendations to rehydrate the next meal by adding some cold water into it, hours before cooking time, and many people do that without any problems, I find such a procedure rather risky. If you are unlucky enough to have unusually large number (not necessarily dangerous number yet) of bacteria in your dehydrated food into which you add some water and put your food container into your backpack in a warm summer day, what do you get? If you have ever seen a laboratory in which researchers try to culture as many bacteria as possible, as fast as possible, you have seen bottles half full of nutritious liquid and bacteria, shaking on a specifically designed table in the set temperature of 37 C (98.6 F) degrees. What is happening in your backpack? Exactly the same. You just created a laboratory standard culture room for bacteria with optimal conditions into your backpack! Good luck with that! I’ll stay with my boiling water strategy.

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