Years ago, when my children were toddlers and I first dipped my toe into the world of home dehydrating, I remember a friend saying, "But why? Food loses all it's nutritional value once you dehydrate it!" In years since, I've heard similar thoughts from friends and readers - but the question is, are they right?
First, let me be clear that today I'm only addressing home dehydrated food. Store bought dehydrated food usually has sugar and preservatives added - which is definitely not something I want for my family. Home dehydrated food, however, has no preservatives and no added sugar (unless you chose to add it). In addition, I'm discussing food that's dried either by the sun or by a conventional electric food dehydrator, not food that's preserved in a home freeze drier, which is something else entirely.
Does Dehydrating Remove Fiber Content? What About Sugar?
A common belief is that dehydrated fruit and vegetables do not contain fiber. This is untrue. The fiber does not dry up and float away - in fact, compared to fresh fruit, there's more fiber in proportion to weight. This is why dried fruit is often used as a remedy for constipation; there's simply more fiber per bite than fresh food can offer.
I also think it's important to note that the carbohydrates or sugar in food do not diminish when that food is dehydrated. Just like fiber, sugar stays put - which means dehydrated food has a higher sugar content than the same food in fresh form.
|Plums prepared for dehydrating.|
Some sources claim dehydrated food loses no minerals, while others claim food "generally retains its mineral content well during the drying process." However, if you blanch food before dehydrating - a practice sometimes used to help retain the food's color and vitamin content - it will lose more minerals than if you don't. Still, the mineral loss is scant.
Does Dehydrating Remove Vitamins?
The quick answer is: To a certain extent. The amount, and which vitamins, depends upon the methods used to dry the food.
According to Harvest Right, the makers of a home freeze drying (not dehydrating) machine, canned food retains 40% of its nutritional value, while dehydrated food retains 60% of its nutrients. (Home freeze dried food, they claim, retains 97% of its nutrients.)
This jibes with what I've read elsewhere; a nutritionist in The New York Times states that a cup of fresh, halved apricots "is 86 percent water, with 74 calories, and a cup of dried fruit is 76 percent water, with 212 calories. Fresh apricots have 3.1 grams of fiber versus 6.5 for dried; 0.6 milligrams of iron versus 2.35 milligrams; 15.5 milligrams of vitamin C versus 0.8 milligrams; and 149 retinol activity equivalents of vitamin A versus 160."
According to the University of Missouri Extension Office website, Vitamins A and C are most likely to see a reduction through dehydrating because they "are destroyed by heat and air." In fact, if you cut a piece of fruit, it will begin losing those nutrients right away, just from air exposure. In addition, heat - including heat used in cooking or dehydrating - reduces the amount of vitamin C in any given food.
What About Enzymes?
|Dehydrated tomato paste (made from tomato skins).|
Whenever you heat food, some enzymes are lost. However, the low temperatures used in home dehydration are less likely to kill enzymes than cooking that same food.
How to Prevent Vitamin Loss in Home Dehydrated Food
The single best way to preserve as much of the nutrients in home dehydrated food is simply to dry it at the right temperature. This is one area where an electric food dehydrator trumps using the oven or a solar dehydrator to dry food: Controlling temperature and keeping it low equals more nutrients in the finished food. This easy guideline ensures that almost all the food's original nutrients remain in place. So it pays to follow the standard heat recommendations for home dehydrating:
Herbs - 95 degrees F.
Nuts and seeds - 105 degrees F.
Fruit and vegetables - 135 degrees F.
Pasta - 135 degrees F.
Meat - 160 degrees F.
* Pre-treating by dipping vegetables and fruit in lemon juice or citric acid. This not only helps prevent browning, but it helps preserve vitamin A and C in the food. Unfortunately, this treatment can also reduce thiamine in dried food.
* Blanching vegetables before dehydrating helps preserve their carotene...but it also lowers a food's vitamin C content and may cause a small amount of mineral loss. Steam blanching is less likely to reduce nutrients in food than blanching in boiling water.
* Not letting the food sit in direct sunlight. This is why dehydrated food should be stored in a dark location - and also why solar dehydrators should have a shading cover (like this one).
* Slicing food evenly, to ensure you don't over-heat and over-dry smaller pieces. Using a mandoline to slice makes this much easier. (This is mandoline I use.)
* Rotating dehydrator trays to prevent over-heating and over-drying of some portions.
* Planning ahead. If a food is likely to only take a couple of hours to dry, for example, don't put it in the dehydrator at bedtime, or by morning it will be over-dried.
* Making Dried Apples in an Oven
* Drying Tomato Skins to Make Easy Tomato Paste
* Why I Love My Dehydrator
* How to Make Jerky in a Dehydrator