FAQ: Freeze Dried & Dehydrated Foods

Questions & Answers - Freeze Dried and Dehydrated Foods

Q. What is the shelf life of freeze-dried and dehydrated foods?

Both options are favorable for long term storage. Shelf life is dependent upon temperature and storage conditions. All stored foods should be kept in a cool, dry location whenever possible. Dry canned items should be stored in areas with little to no humidity (15% humidity or less) for longest shelf life. See Food Storage Recommendations.

Predicting actual shelf life of freeze dried and dehydrated foods is not an exact science; however, many studies have been done. Shelf life of storable foods can be dramatically increased by lowering the constant temperature. It is possible to double, triple, or even quadruple the shelf life by lowering the temperature proportionally. The basic rule of thumb is to store your food items in the lowest temperature possible -- a constant temperature between 40–60 degrees F is ideal to maintain estimated shelf life and retain nutritional value. In general, the most susceptible ingredients to aging are products with dairy items, shellfish, brown rice, and tree nuts.

  • Mountain House #10 Cans: Mountain House #10 cans will store for 30+ years when stored as recommended in a cool, dry environment. Recommended storage temperature is 72 degrees F or less (above freezing) with little to no humidity. Shelf life is dependent upon storage conditions.
  • Mountain House Pouches: Mountain House pouches have a 30+ year shelf life (announced in July 2016) when stored at room temperature (except Ice Cream products, which have a 2-year shelf life). There are no humidity requirements for pouch products. Recommended storage temperature is 70–75 degrees F or less (above freezing). Shelf life is dependent upon storage conditions.
    See the Mountain House Taste Guarantee for additional information.
  • Peak Refuel Pouches: Currently, all Peak Refuel meals are labeled with a 5-year "best by date" — however, being 100% fully freeze dried and having the same packaging process as others that claim a 25+ year shelf life, Peak Refuel products should store much longer than the current 5 year stated best by date. Being a young company, only 4 years in business, Peak Refuel has not been able to do the testing to claim the 25+ year shelf life...yet...but plan to as they get older as a company.

Q. What happens after the shelf life has "expired"?

Many manufacturers do not specify an "expiration date" — but instead use a "production date" or "best if used by" date. These dates should be used to determine the shelf life of products for long-term storage. If the products are stored under recommended conditions and the product packaging (can or pouch) is unopened and unpunctured, a slight difference in taste and appearance in product contents may be noticed.

A food’s palatability life is the point at which undesirable changes occur to foods taste, texture, color, and cooking qualities. This is the reason for the "use by" and "sell by" dates on many foods and for the shelf life of foods in general. Palatability will almost always be in excess of good nutritive life. If you don’t have anything to replace old food with, it’s not necessary to throw the food out just because it’s reached the end of its best palatable storage life. Do, however, keep in mind that advancing age will only further decrease the useful nutrition, increase the foods’ unattractiveness, and increase the chances that something may cause the food to spoil, especially when not stored as recommended.

Q. How do freeze-dried and dehydrated foods differ?

The freeze-drying process uses cold temperatures where fresh or cooked foods are flash frozen. Moisture is then removed in a vacuum chamber, as a low-level heat is applied to evaporate ice without returning it to a liquid form. Since the food remains frozen during the process, the food's cell structures do not change and the products generally retain the original taste and nutritional values.

The dehydration process uses hot temperatures. Some items (such as as apples and onions) are better when dehydrated (retaining nutritional values and tasting better when dehydrated). Dehydrated-only items include dried beans (navy beans, pinto beans, black beans, lentils), diced carrots, chopped onions, diced apples, and diced potatoes, for example.

NOTE: Freeze-dried and dehydrated foods require clean, drinkable water to rehydrate prior to consumption.

In Summary:

  • Taste: Dehydrated foods do not typically have any additional ingredients (i.e., seasonings), and usually require cooking and seasoning. Cooking times vary, but most are added to hot boiling water. By adding water, the food is "rehydrated" back into its original natural state before dehydration. Most dehydrated food will benefit from adding seasonings and other items (i.e., dehydrated vegetables, rice, meat, potatoes, etc. and seasoning, such as salt, pepper, Tabasco® sauce, garlic). Pasta doesn’t taste like much until something is added (Spaghetti is a favorite, but it's all in the sauce). Any ingredients or topping can be added to dehydrated foods. Seasoning is recommended simply for taste.Freeze dried foods, on the other hand, are usually foods containing a multitude of ingredients and seasonings. No additional ingredients are needed—just a little cook time in hot water to rehydrate and be ready to eat. Freeze-dried foods are typically pre-seasoned, pre-cooked, and pre-mixed with other ingredients, making fast, easy, and tasty meals.
  • Cooking: Cooking/heating times are pretty short, usually 10–15 minutes for most foods. Some items, such as rice, legumes, and wheat (whole grains) take longer to cook and can be simmered for 30 minutes to an hour or more. Dehydrated and freeze dried foods are rather easy to prepare and cook.
  • Seasoning: Dehydrated food may be seasoned for best taste. Freeze dried entrees don’t require additional seasoning.
  • Ingredients: Freeze dried foods don't require additional cooking or adding ingredients to make a complete meal. With freeze dried items, you simply add hot water and wait about 10 minutes. This rehydrates the food completely and it’s ready to eat! Mountain House products are 100% freeze dried. Dehydrated foods are usually single ingredients. You can mix any dehydrated food with any other food product for a combination of tastes, textures and varieties.
  • Best Value: Dehydrated foods usually cost less than freeze dried food but, if you don't like to cook and want great food with great taste, freeze dried food is the hands-down winner.

Q. Why are some products sold in both freeze-dried and dehydrated varieties?

There are benefits to each. Freeze-dried foods rehydrate more quickly and dehydrated foods condense further, allowing more to be stored in less space. Often, dehydrated foods are processed in a "raw" form while many freeze-dried foods are processed in a "fully cooked" condition.

Q. Are any nutrients lost during the freeze-drying and dehydration processes?

Freeze Dried Food: The product remains frozen during the freeze-drying process, and as such the product’s cell structures do not change.  Almost 100% of the water is removed during the freeze dry process, reducing the food’s weight by about 90%. Freeze-drying is generally more expensive than dehydrating. Uniform, low temperature storage conditions are recommended. Some specifics include:

  • Freeze dried food retains the fresh flavors, vitamins, nutrient values, colors, and aromas of the original ingredients.
  • Freeze-dried fruits have antioxidant phytochemicals almost as high as the fresh fruit.
  • To get the nutritional benefits of freeze-dried fruits and vegetables, the correct serving size is about 1/4 cup, according to the American Institute for Cancer Research.
  • Freeze-dried fruits maintain vitamins such as E and contain folic acid.
  • Foods containing vitamin C tend to have lesser amounts of the vitamin in freeze-dried form as compared to fresh.
  • The freeze-drying process allows food to maintain its nutritional value while also providing a long shelf-life.

Dehydrated Food: Some products are better suited for dehydration (90-95% of moisture is removed), as it allows the product to reconstitute back to its original state more easily (onions, bell peppers, tomatoes, celery, carrots, and mushrooms for example). Here are some specifics about dehydrated foods:

  • Vitamin A is retained during the dehydration process.
  • Some Vitamin C is lost during the dehydration process because Vitamin C is an air-soluble nutrient and food drying is an air-based process. When a food is sliced and its cells are cut, the surfaces exposed to air lose some Vitamin C during dehydration.
  • The Caloric value of a fresh food stays the same when it is dehydrated, although some dried foods (i.e., fruits) taste sweeter because the water has been removed and the sugar is concentrated.
  • Dried fruits and vegetables are high in fiber and carbohydrates, neither of which is affected by the dehydration process. Dried fruits and vegetables are also naturally low in fat. Minerals (i.e., potassium, sodium, magnesium, etc.) are not altered when fresh fruit is dried.

Q. Do you offer freeze dried food for those with dietary restrictions?

Yes! Both Mountain House and Peak Refuel have product options for those with dietary restrictions:

  • Gluten Free
  • Dairy Free
  • Soy Free
  • Vegetarian
  • No Pork

Q. What about Dented Cans?

Minor dents and scratches on #10 cans will have no effect on the shelf life of the can contents unless the seam or end seal is compromised. Even severely dented cans can store for many years although we discourage storing cans with large dents or with seam seal breaks.

Please see our April 2013 taste test review of a Severely Dented Can of Chili Mac with Beef that we received in May 2011. After two years of storage, we decided to see if the food was compromised in any way. Upon opening the can, there was no unusual odor, color, or texture of the contents, as proof that even the contents of a severely dented can are still safe to eat and tastes great!

Q. How do I properly rehydrate freeze-dried or dehydrated foods?

Most freeze-dried and dehydrated items are reconstituted by adding hot/boiling water, waiting about five to twelve minutes, and draining the excess water if necessary. Follow instructions on the product packaging.

Q. Do I need to rehydrate the entire contents upon opening the container?

Not all of the product inside of the container must be rehydrated upon opening. Each product identifies the amount of dry product and amount of water needed to rehydrate. Scoop out the needed dry product and reseal the package for later use.

Helpful Hint: Give the container a good "shaking" prior to scooping out dry product for smaller serving portions since the ingredients tend to settle during storage.

Q. How long does freeze-dried and dehydrated food last after opening?

As a general rule, most manufacturers recommend using opened packages within one to three weeks after opening* — Treat any leftover food as you would fresh food.

However, in ideal storage conditions, the product may stay good for up to several months or even years after opening.

CAUTION: Products containing dairy, shellfish, brown rice, or tree nuts should generally be consumed within a week or two after opened.

Q. Why are sodium levels so high in the storable food products?

Emergency storable food products were originally designed to fit a high-performance lifestyle, replacing some of the sodium lost during heavy exertion.

Q. How does higher elevation affect cooking time?

The boiling point for water drops one degree Fahrenheit for every 550 foot rise in elevation, so cooking time doubles for every 5,000 feet above sea level. Presoaking and simmering ingredients may be helpful to minimize cooking/heating time. Always cover pot while cooking/heating to allow ingredients to completely rehydrate/reconstitute.