Freeze Drying vs. Dehydrating: 5 Differences That Matter

Dried fruits and vegetables are delicious and healthy snacks whether at home or while you’re camping. Freeze-drying and dehydrating are two methods of food preservation that have been around for decades. However, while some people use these terms interchangeably, there are five significant differences between these two methods.

Differences that matter between freeze-drying and dehydrating include the way moisture is removed from foods, the nutrition value and shelf life of the dried foods, the equipment needed for each process, and the texture and taste of the finished products.

Ultimately, the foods go through a similar process of removing the liquid. However, understanding the differences between these food preservation methods is helpful in determining which one is right for your purposes. This article will cover everything you need to know about freeze-drying and dehydrating foods. 

What Is Freeze Drying?

Freeze-drying foods are a relatively new concept in the grand scheme of things. It is a food preservation technique invented in 1906 by a French scientist named Jacques-Arsene d’ Arsonval.

It was not until almost fifty years later that foods were freeze-dried on a large, industrialized scale. Over the last one hundred years, freeze-drying has been used on a number of foods, pharmaceuticals, and other heat-sensitive products. 

Phases of Freeze Drying

The process of freeze-drying is an expensive one and requires specialized equipment. Its different phases are as follows: 

  • Freezing Stage: The first and most important phase is the freezing stage. Foods are frozen rapidly at extremely low temperatures, as low as -40°F (-40°C). The rapidness at which the foods are frozen is critical in preventing ice crystals from forming, potentially ruining the final product. 
  • First Drying Phase: Next, the foods go through their first drying phase. They are placed in the bag, the air is vacuumed out, and heat is applied to lower the pressure in the bag. This phase removes all but 5% of the food’s moisture and can take anywhere from a few hours to a couple of days. 
  • Water Removal Phase: The third and final phase of freeze-drying makes an attempt to remove any water that was not removed during the second phase. The food is once again exposed to higher temperatures to lower pressure to remove extra moisture. By the end of this process, freeze-dried foods contain as low as 1% of their original moisture content, enabling them to have a shelf life of a few decades. 

Pros of Freeze Drying

The variety of foods that can be freeze-dried is practically endless, which makes it an excellent option for camping and survivalists. Some of the foods you can freeze dry include meats, vegetables, fruits, coffee, dairy products, and seafood. You can pack an entire day’s worth of freeze-dried meals, and they will rehydrate quickly, easily, and deliciously. 

Perhaps more importantly, your meals will retain almost 100% of their nutritional value. The rapid freezing method allows for nearly all of the essential vitamins and minerals to stay in your food, making for a convenient and nutritious meal while you are camping or backpacking. Foods also keep their natural colors and flavors, which makes for a beautiful and healthy meal. 

Another benefit of freeze-dried food is that it lasts for decades. That’s right – your freeze-dried fruits, vegetables, and meats can last up to 25 or 30 years if they are stored and appropriately packaged! Freeze-dried foods should be stored in a dry place with a very tight seal; Air-tight containers and vacuum-sealed bags will work well. 

Cons of Freeze Drying

One of the most significant drawbacks of freeze-drying foods is that it requires specialized equipment. Most people cannot do it themselves at home. Freeze dryers typically cost thousands of dollars, even for the small ones. While some freeze-dried foods are accessible at the grocery store, you may not find all the foods you want, making it much less accessible for some people. 

The second drawback of freeze-dried foods is the cost. After you consider the special equipment required for freeze-drying, labor hours, and energy of preserving foods using this method, the foods tend to be more expensive than dehydrated foods.  

What Is Dehydrating?

Food dehydration is one of the oldest methods of food preservation. This method dates back thousands of years ago and was likely discovered by accident. It evolved as a popular food preservation technique out of necessity, as freezers and refrigerators could not extend the shelf life of foods back then. Today, most dehydrated foods retain only about 5 to 20% of their original moisture content. 

It wasn’t until the Medieval period that Europeans began to dry out their fruits, vegetables, and herbs by fire in specially built rooms and buildings.

Like in freeze-drying, French inventors had a big hand to play in developing the first industrialized dehydration techniques. By the mid-1800s, they had figured out how to dry fruits and vegetables with air temperatures of over 100°F (37.7°C). 

Since then, the popularity of dehydrated foods has ebbed and flowed in the United States. It often regains popularity during times when people recognize a need for lightweight and long-lasting foods.

For example, its first boom in popularity came during World War II when soldiers needed compact and lightweight nutrition. Dehydrated foods became popular again in the 1960s when U.S. hikers and campers discovered how easily they can be carried. 

Dehydrating foods is conceptually a much simpler process. When you break it down, it simply evaporates moisture from foods by exposing them to heat for a long time.

When you remove the moisture from foods, they will last much longer. In the case of dehydrated foods, they can last several years if they are appropriately packaged. The ease of dehydrating makes this very attractive to survivalists and campers. 

Pros of Dehydrating

One of the best things about dehydrated foods is that anyone can do it. In many cases, you don’t need any equipment and can use the sun to evaporate the moisture. However, this only works in hot, dry environments. Putting the cut-up foods in the oven or air fryer at low temperatures for 5 to 7 hours will typically do the trick. 

Similar to freeze-dried foods, the list of foods that you can dehydrate is quite long. While fruits and vegetables are the most common, you can also dehydrate herbs, meats, grains, and bread. These foods make great snacks, salad toppings, and even full meals. 

Cons of Dehydrating

Exposure to heat removes a lot of the great nutrients from dehydrated foods. Some essential nutrients, like Vitamin C, are heat-sensitive, and much of their benefits are lost in the process before the food even makes it to your plate.

However, plenty of nutrients are not sensitive to heat, such as fiber, so eating dehydrated fruits and vegetables isn’t a total loss. In general, you can expect that dehydrated foods retain about 60% of their nutritional value. 

Dehydrated foods become much lighter and more compact when you remove all of their moisture. While this is great for traveling light, it is more difficult to judge how much you are consuming. For example, if you eat a cup of fresh blueberries, it is only about 80 calories and 13 grams of sugar.

Alternatively, a cup of dried blueberries has 150 calories and 27 grams of sugar. You can easily consume almost double the calories and sugar without noticing. 

5 Notable Differences Between Freeze Drying and Dehydrating

Many people use the terms freeze-drying and dehydrating interchangeably, but they are two very different processes, as you can see from the sections above.

This section will explore five notable differences between these two methods of food preservation and will also help you know which method will best suit your needs. 

Nutrition Value

One of the best things about freeze-dried foods is the incredible retention of all of the essential vitamins and minerals. Rapidly freezing and drying foods does not damage or kill nutrients the same way exposure to heat does. So, if you are looking for nutritious dried meals, freeze-dried is the way to go. 

On the other side, dehydrated foods lose a lot of their nutritious value through the process of dehydrating. The prolonged exposure to heat kills a lot of the nutrients we need from our foods. Some estimates suggest that they lose as much as 40% of their nutritional value when they are on your plate.

In addition to losing nutrients, it can be harder to monitor your caloric and sugar intake when you are eating dried foods. 

Shelf Life

Freeze-dried foods are the perfect food for survivalists because of the extremely long shelf life. As said earlier, freeze-dried foods can last up to three decades if they are packaged in air-tight containers and a dry environment. Furthermore, it retains its nutritional value for that length of time as well. 

On the other hand, dehydrated foods only have a shelf life of up to five years. One of the biggest contributors to the significant difference in shelf life is the amount of moisture absorbed from the foods. Most dehydrated foods still have up to 20 % of their original moisture content, making their shelf life a lot lower than freeze-dried foods.  

Rehydrating

Freeze-dried foods can be rehydrated quickly and easily. To rehydrate, simply put some hot water with the food in the microwave, and voila! You have a rehydrated meal that tastes, looks, and smells as if it were a fresh meal. You can also heat it on the stove-top or over a fire. 

Dehydrated foods take a longer time to rehydrate and don’t even taste the same as fresh food. In the first part of the rehydrating process, the foods must be soaked in water for at least twenty minutes, but potentially as long as an hour and a half. 

Equipment

As previously noted, the method of freeze-drying foods requires highly specialized and costly equipment. Most people would not spend several thousand dollars on a freeze-dryer, limiting you to the foods you can find at the grocery store or farmers market. For example, this Harvest Right Home Freeze Dryer has a capacity for only seven pounds of food but will cost thousands of dollars. 

Alternatively, dehydrating foods does not require special equipment. People in some parts of the world can dehydrate foods themselves by allowing their fruits and veggies to lay in the sun for several hours in a dry environment. Of course, if you wanted to, you could use equipment to dehydrate.

The Cusimax Dehydrator is much more affordable than the freeze-dryer and will work well for people in more humid environments that can’t rely on the sun to dehydrate food.

Texture and Taste

Another great thing about freeze-dried food is that the taste and texture are almost exactly the same as fresh foods when you rehydrate them. Once again, the method of rapidly freezing and then drying the foods does not alter these components. Freeze-dried foods have more of a fluffy, light, and porous texture before they are rehydrated. 

On the other hand, dehydrated foods have a slightly less desirable texture. They are often brittle and tough in texture. Sometimes they have a leather-like feeling when you chew them.

The taste of dehydrated foods can change quite a bit as well, so make sure you taste them before you get committed. A great, well-known example is jerky. While still delicious, the texture and taste are completely different from the fresh food.