What Is Freeze-dried Food?


I first ate Freeze-dried food doing a section hike on the Appalachian Trail in Vermont. I looked forward to my nightly freeze-dried dinner, that’s how good some of the meals are. As a lightweight hiking food, for long-term storage, or emergency preparedness, freeze-dried food is arguably the best choice out there.

What Is Freeze-dried Food?

Freeze-dried food is processed to remove 97% of its moisture, increasing shelf-life 25 to 30 years, retaining 97% of its nutritional value. Freeze-dried food is used primarily for outdoor activities like hiking and emergency preparedness. Freeze-dried food is made ready to eat by adding hot water. 

How Freeze-dried Food Is Made

Freeze-drying (also known as lyophilization) of food uses a process called sublimation that removes moisture by lowering the pressure in a vacuum and fast freezing the food. The temperature in the vacuum slowly increases, causing the ice in the food to vaporize, dehydrating it.

Is Freeze-drying Food The Same Thing As Dehydrating Food? 

Freeze-dried food and dehydrated food have different characteristics, especially when it comes to nutritional value and storage life. Check out the comparison chart below to get the fundamental differences between the two.

Comparison Chart Of Freeze-dried Vs. Dehydrated Food

CharacteristicsFreeze-dried FoodDehydrated Food
Method of DehydrationDeep-freezing in a vacuumHeat*
Shelf-Life**25 to 30 YearsSelf-processed: 1 to 10 Years
Commercially Processed:15 Years
Retained Nutritional Value95% to 97%40% to 60%
TasteHigh QualityLoss Of flavor
Moisture Removed95%60% to 80%
Prepping Time To Eat12 Minutes20 to 30 Minutes
CostHighRelatively Inexpensive
Stock RotationNot-requiredRequired
Do It Yourself Method Of ProducingHome Freeze DryerElectric Dehydrator
Optimum Storage TemperatureUnder 75° FUnder 75° F
Food Can Be PurchasedYesYes
Requires RefrigerationNoNo
*Regular dehydration uses heat to remove moisture, which removes nutritional value. Heat also removes less moisture than freeze-drying.
**Food Shelf-life will vary depending on the type of food, the packaging, and the storage environment
Mountain House 30 Year Shelf Life Click Here

Dehydrated food has 1/2 the nutritional value, 1/2 the flavor, and 1/2 the shelf-life of freeze-dried foods. If you can afford it, freeze-dried foods are a superior choice for long-term storage and emergency preparedness.

Storing Freeze-dried Foods

Properly store Freeze-dried food in vacuum packing, and you’ve eliminated two of the main threats to a food’s shelf-life, moisture, and oxygen. Now all you have to worry about is keeping the temperatures down.

Optimum storage temperatures for freeze-dried foods are between 32°F to 77°F, but room temperature is acceptable. Keep in a dark location away from light, humidity, and heat fluctuations.

Foods That Can Be Freeze-dried

You can freeze-dry just about any food that contains moisture. Some foods do not freeze-dry well like foods with high oil content (peanut butter) or foods that will turn into a sopping mess when rehydrated (bread.)

Foods You Can Freeze-DryFoods NOT To Freeze-Dry
DairyPeanut Butter
FruitsPure Chocolate
VegetablesButter
MeatHoney
Entire MealsSyrup
DessertsJam
CoffeeBread, Cake, and Muffins


Check out the Video, Freeze-Dry Meals at Home, with the Harvest Right Freeze Dryer.
I have no vested interest in Harvest Right, but they are the industry standard for home freeze-dryers.

How Do You Rehydrate Freeze-dried Food?

  • To rehydrate freeze-dried meals add warm or boiling water and wait for 10 to 12 minutes (Use a pan on the stovetop or a bowl to rehydrate individual ingredients)
  • Vegetables: Eat dehydrated as a crunchy snack or rehydrated in hot or boiling water
  • Meat: Place raw or cooked freeze-dried beef in a bowl of hot water. You can’t use too much water with meat. It won’t get soggy.
    • Pre-cooked dehydrated meat can be rehydrated in broth or sauces, i.e., hamburger and tomato sauce.
    • Use rehydrated raw meat the same way you would use it from the store. Rehydrate and cook.
  • Fruit: Eat dry or add a little bit of water at a time to avoid sogginess

The Upside Of Buying Or Making Freeze-dried Food

  • Freeze-dry the foods that you eat in your regular diet, you are not limited to the basic meals provided by a commercial freeze-dryer
  • Freeze dried-foods have the most extended shelf-life of any preserved food
  • Freeze-dried food retains its nutritional value
  • Any fresh or cooked food that contains moisture can be freeze-dried
  • You can survive by eating freeze-dried food and drinking fresh water.
  • Freeze-dried food does not require refrigeration before rehydration.
  • Food quality is excellent
  • Freeze-dried food is super lightweight, so it keeps pack-weight low
  • Conserves storage space if vacuum packed
  • Don’t waste your leftovers
  • Make larger meals with the intention of freeze-drying the excess
  • Save up to 1500 lbs of food per year freeze-drying at home (Harvest Right)
  • Save money by freeze-drying garden produce or meat you find on sale
  • If organized with your freeze-drying, you can save some serious money on food, and you will eat better
  • Make and sell freeze-dried food for profit
  • Requires less prep time than canning food

The Downside Of Buying Or Making Freeze-dried Foods

  • Commercially packaged Freeze-dried food is super expensive
  • A 1-year supply of commercially packaged freeze-dried food costs thousands of dollars
  • Home- freeze-drying-machines start at $2000.00+
  • Expenses are relative, depending on usage and food savings. Also consider the cost of packaging: oxygen absorbers, mylar packaging, and vacuum packer
  • The more capacity a home-freeze drying unit has, the more the unit will cost 
  • Home freeze-drying units are Noisy (the vacuum pump is loud
  • Home freeze-drying units use electricity. However, you can get rid of large freezer chests if you freeze-dry everything
  • Home Freeze Drying units require maintenance, like a routine oil change on the vacuum pump, (you can purchase an oil-less pump, but they are more expensive)
  • It takes 24 to 48 hours of drying time for each batch of food. The amount of time to dry depends on the food’s specific moisture content.  
  • Home freeze-drying units have a weak point: The vacuum pumps have a limited life-span. However, the replacement cost is much less than the total unit
  • Home freeze-drying units Take Up Floor Space (smaller than a chest freezer)

Check out the Video, Why Freeze Dry?, by Harvest Right

Does The Freeze-drying Process Kill Food-Borne Bacteria Like Salmonella Or E-coli? 

The Freeze-drying process slows the growth of bacteria, but it doesn’t kill it. Freeze-drying food does not kill bacteria, Salmonella, or E-coli.

How Does A Home Freeze-dryer Work?

  • A home freeze-dryer uses a process called sublimation to remove moisture from food by lowering the pressure in a vacuum and fast freezing. The temperature in the vacuum slowly increases, vaporizing the ice in the food, dehydrating it.
  • A home freeze-dryer quickly brings food temperatures down to -30°F to -50°F within hours. 
  • A vacuum pump removes air from the food chamber. 
  • The temperature is raised slowly, allowing moisture to be removed from the food and vacuum area.

The sublimation process uses the evaporation of ice crystals versus burning water out of the food.

Freeze-dried Foods Have Different Shelf Lives

You may have noticed that some manufacturers and home-freeze drying companies have a shelf-life of 25 years while others advertise a shelf-life of 30 years. That’s kind of confusing if you don’t know why.

Shelf life can be affected by a number of things but all things being equal the shelf-life is based on quality control and how long a company has been around to do the testing.

Mountain House, the company that made the first freeze-dried meals for the U.S. military, has a long track record with their freeze-dried meals. They can advertise a 30-year shelf life because they’ve been around long enough to test their meals and packaging. This is why you see different shelf-lives between commercially provided freeze-dried meals.

Mountain House Blog Quote

Actual Mountain House meals stored for at least 30 years in real-world conditions meet consumer expectations of ‘tasting good.’

This was corroborated by numerous astonished reviewers of Mountain House Military meals that had been stored for up to 42 years

Mountain House is the only brand in the industry that can legitimately make this claim.”

Mountain House Blog, July 26, 2016

As a side note, I’m not selling Mountain House meals but I’ve eaten them and can attest to their quality. I have not eaten a 30-year-old freeze-dried meal.

Check out this article On the Mountain House blog if you are interested in reading more about how they came up with a 30-year shelf-life for their freeze-dried foods. Click Here

Helpful Documents

If you’d like to get a feel for how to freeze-dry your food and how a home freeze-dryer works, check out this PDF from Harvest Right. It covers the A to Z’s of freeze-drying. Click Here

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