What’s the Difference Between Freeze Dried and Dehydrated Food?

When you dive into the world of preparing food for outdoor adventures or for disaster preparedness reasons, at some point you’re likely to come across the topic of dehydrated vs. freeze-dried food. Both outdoorspeople and preppers are often confused by the distinction between the terms (rightfully so), and many people think freeze drying and dehydrating are the same thing, which they are not.

Freeze-drying is a form of dehydration, and thus freeze-dried food is a type of dehydrated food. But freeze-drying is a specific process, and in everyday usage a freeze-dried meal (like those we offer here at Mountain House) means something different than a dehydrated ingredient.

In this post, we’ll compare dehydrated vs freeze dried food and weigh the pros and cons of each from the standpoint of outdoor recreation and emergency preparation.

Dehydrating vs Freeze-Drying

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Freeze drying and dehydrating are both commonly used food preservation methods, but the processes and end results differ greatly. The primary difference lies in their approach to moisture removal and the quality of the final product.

Dehydration is an ancient method of preserving food: people have been drying sustenance in the sun to make it longer-lasting, more storable and packable for thousands of years. As the name suggests, dehydrating food means removing as much of the moisture content from it as possible through the use of heat and airflow. This lengthens the time it’ll withstand microbial breakdown and other decay. However, this process relies on evaporation which can alter the food’s taste, texture, and nutritional profile.

Freeze-drying, also known as lyophilization, is a more technologically involved process than basic dehydration, as it subjects foods to freezing first and then a moisture-vaporizing vacuum to remove the water content. The freeze drying process preserves the food's structure, nutritional value, and results in a product that tastes just like fresh food when rehydrated.

Although freeze-drying is a modern technique, it essentially mimics the ancient method used by the Incan Indians, who transported their produce from low elevations to the high altitudes of Machu Picchu, naturally “freeze-drying” their food over weeks. The contemporary process optimizes this by removing water from the product in just hours or days, significantly speeding up the preservation while maintaining the benefits of long shelf life and nutrient retention.

MOISTURE REMOVAL DIFFERENCES

Standard dehydrated food generally has about 80-95% of its moisture removed, depending on the specific process and other factors. By comparison, freeze-dried food removes some 98-99% of the product’s moisture.

Both methods create foods that are more shelf-stable, lighter and more compact, which means maximized storage capabilities and less shipping resources needed.

For outdoors people, the appeal of both freeze-dried and dehydrated foods is obvious: you get to bring ingredients and ready-to-go meals out into the wild without breaking your back or requiring a whole packstring to do so. You can enjoy more varied flavors out in the backcountry where you may not have access to cold storage.

For those who are looking for food for emergency preparedness reasons, both of these types of foods are also appealing due to their long term storage capabilities.

So, Which is Better?

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The benefits of freeze drying food typically outweigh those of dehydrating food. People tend to lean towards freeze-dried meals to both bring along on outdoor adventures and for long term food storage needs.Here are the major advantages of freeze drying:

• More Nutritional and Flavorful - The vacuum process used in freeze drying better preserves the internal structure of food: moisture is removed while the pore space remains. When the food’s rehydrated, it tastes the same as it did when it was first cooked, and the nutritional content it delivers is also the same. 
• By contrast, the heat involved in the standard dehydration process changes the food’s original flavor and texture, and can result in a 40-50% loss of nutritional value.
• Lightweight and Longer Shelf Life - Because the lyophilization process removes much more moisture, freeze-drying produces a lighter product which is great for packing meals for a backcountry trip. The same residual moisture in dehydrated food that makes it a bit heavier, also makes the food have a shorter shelf-life: often only a few years. Compare that to the decades that freeze-dried food can last (Mountain House freeze dried meals are guaranteed for 30 years!).
• Most Versatile - you can freeze-dry just about any kind of food, whereas the items you can realistically, satisfactorily dehydrate are more limited (dehydrated fruits, veggies, and jerky are most common). From pasta primavera to pad Thai to ice cream, opting for freeze-dried meals means you have more variety to choose from when making  backcountry cuisine.
• Faster to Rehydrate - since the structure of freeze-dried food hasn’t been altered, it’s faster to rehydrate than dehydrated food. Mountain House meals can be rehydrated in just minutes! This means less prep time and less camp stove fuel wasted.

Dehydrated foods can make great snacks, but when it comes to needing a full meal, freeze dried food offers a much better option. 

That said, if you’re looking to preserve food at home on your own with a do-it-yourself method, dehydration is likely the best way to go. Whether you’re purchasing a food dehydrator or setting up some other kind of air or sun-drying system, this process is more straightforward and cheaper. Freeze-drying is a more complex undertaking that requires expensive, specialized equipment.

Mountain House’s History with Freeze-Drying

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It wasn’t long after freeze-drying proved its worth during the Second World War that Mountain House’s parent company ( Oregon Freeze Dry), got its start in 1963, producing freeze-dried fruits for breakfast cereals. The company quickly began supplying freeze-dried meals to the U.S. military as well as astronauts, and by the end of the decade, the Mountain House brand was born to serve (quite literally) the booming outdoor industry’s appetite (learn more about their backstory here).

OUR FREEZE-DRYING PROCESS

The process of freeze-drying we use here at Mountain House involves crafting delicious recipes with high-quality ingredients, cooking our meals, freezing them on specialized trays, then placing these trays of frozen goodness in a vacuum chamber to subject them to an air pressure about equivalent to that 46 miles above the surface of the Earth.

The frozen-food trays in the vacuum are also gently heated at a low temperature - the combination of that heat and the vacuum environment causes the moisture in the foodstuffs to sublimate directly into water vapor, which is removed so as not to re-enter the food.

Once this process is complete, our proprietary packaging process begins. We take the freeze dried meals and put them into convenient, bowl-like pouches that provide a great vessel for easy rehydration. Then all that’s left is for you to enjoy a delicious, comforting meal! 

Choose Mountain House Freeze-Dried Food for Your Next Outdoor Adventure

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As our historical snapshot earlier in this article suggests, we’ve been doing the freeze-drying thing a very long time here at Mountain House. It’s been our absolute honor to serve multiple generations of hikers, backpackers, river runners, mountain climbers, hunters, anglers, preppers, and more, and we look forward to doing the same for generations to come!

We invite you to taste for yourself just how tasty freeze-dried food can be out there in the wilds (and even in the home kitchen when you need something quick and delicious). From breakfast items such as our Biscuits & Gravy, our Granola with Milk and Blueberries, and our Scrambled Eggs With Bacon to our Creamy Macaroni and Cheese, Fettuccine Alfredo with Chicken, Chicken Fajita Bowl, and other entrees, we’ve got you covered with home cooked flavor wherever you roam.