Freeze-Dried & Dehydrated Explained
When heading out for a backpacking or camping adventure, it can be a struggle to choose between packing dehydrated or freeze-dried ingredients for the backcountry menu. And rightly so: there are some key differences to be aware of, with the most differentiating factors being cost, cook-time, weight, water need for rehydration, and the amount of space they take up in the pack.
|Freeze-Dried Spinach||Dehydrated Spinach|
|Shown: 0.5 oz/1cup||Shown: 0.67 oz/1 cup|
|Freeze-Dried Food||Dehydrated Food|
~ 1 – 20 minutes
|3 minutes -1-1/2 hours
in cold water
5-20 minutes in boiling water
What is Freeze-Dried Food?
Freeze-dried food is fresh or cooked food item that has been frozen – then had the water removed. The result is a light-weight, fresh appearing and tasting preserved food that can be rehydrated with a minimum amount of water: making them a great option for backpackers.
The process involves freezing a fresh food (fruit, dairy, vegetable, cooked meat or fish) in a special “freeze drying chamber,” then removing the water by quickly changing the chamber’s pressure and temperature. This causes the water in the food to change from a solid to a gas without ever changing back into a liquid. This “quick change” process preserves the cell structure of the food without compromising vitamins, nutrients, color or aroma1. Because the freeze-drying process requires specialized equipment, it is not something the average backpacker can do themselves at home; however, freeze-dried ingredients and meals are readily available in a variety of retail stores.
What are the Advantages of Freeze-Dried Food?
Since all of the water and oxygen have been removed from freeze-dried food it does not require refrigeration when stored and is, therefore, considered to be “shelf stable.” This means the food is safe to store at room temperature for long periods of time without refrigeration. And although all food is best when eaten as soon as possible after being packaged, the properties of freeze-dried food allow it to last several years when stored in a cool dry location.
Water is the main source of weight in all food; and alll fresh foods contain water. However, once the water has been removed, the weight can be reduced by as much as 70% – 90%. For example: a package containing one-half pound of frozen cooked chicken will weight a mere 2 ounces once it is freeze-dried1. Now that’s a significant reduction in weight!
Fast Rehydration Time
Freeze-dried foods are very moisture sensitive; SUPER moisture sensitive, in fact! They will, therefore, rehydrate in a matter of minutes when exposed to water. Freeze-dried items can be fully reconstituted with cold water or hot waterl, but the time to achieve the desired texture may take longer with cold water for some items, like meats. This being said, it is important to keep freeze-dried food in a moisture-proof environment – since any degree of moisture will impact the stability of the food item. Unlike dehydrated food, most freeze-dried fruits and vegetables can be eaten ‘raw’ (without adding any water) and usually have a crispy texture similar to a potato chip. This makes them a good choice for a tasty and healthy trail mix in addition to using them for in-camp recipes.
Cooking Tip: Freeze-dried foods are pre-cooked; therefore, due to the quick rehydration time, freeze-dried food may be incorporated into the recipe toward the end of the cooking cycle to lend a more “fresh crunch” texture to the dish or to retain a more “fresh food” flavor.
The Freeze-Drying process uses very low levels of heat – and this makes it possible for most foods to closely retain the taste, texture and aroma of it’s fresh state when rehydrated; therefore most people find the flavor and texture of freeze-dried foods superior to dehydrated .
How is dehydrated food made?
|Dehydrated or dried food is made by slowly removing the water from the food through the use of heat. This is a practice that has been performed for hundreds of years with previous generations relying on air drying, sun drying, smoking or wind drying to achieve the desired results for preserving the harvest.
Today, dehydrated fruit and vegetables are made commercially and can be purchased through any number of food outlets like Packit Gourmet; however, a wide-range of individuals – including self-sufficient outdoor enthusiasts – prefer to dehydrate their own ingredients through the use of a commercial home dehydrator or convection oven. Although this “do-it-yourself” method is very time consuming, it provides a low-cost option that allows individual control over the ingredients and flavors that go into meals.
Tomatoes in Dehydrator
What are the advantages of dehydrated food?
Like freeze-dried food, dehydrated food is preserved by having all of the water removed; thus making it safe to store it at room temperature for long periods of time. Although all food is best when eaten soon after being dehydrated, when stored properly, dehydrated food can be stored safely for many years without losing flavor.
Dehydration removes about 98% of the water content from fresh food, making it considerably lighter and easier to store.
When fruits and vegetables are dehydrated, the plant cells compact making each piece of dehydrated food considerably smaller. Although this results in shriveled looking appearance, the food plumps back to life quickly when added to boiling water. Freeze-dried food on the other hand, retains its original shape making it nice looking; but it also takes up more space than the more compact dehydrated food.
Dehydrating food is simple and does not require expensive machinery; it can easily be made at home with a countertop dehydrator. This makes dehydrated food much less expensive than their freeze-dried counterparts, especially when you consider the savings of doing-it-yourself.
Fruits and vegetables sacrifice very little flavor through the dehydration process; however, because the resultant texture is more “chewy,” many consider them slightly less desirable than freeze-dried. Dehydrated ingredients stand up well in dishes requiring a longer cooking time, and imparts a rich flavor to soups, gravies or sauces.
Published on wiki.backpackinglight.com by Packit Gourmet, November 2008