Most of the articles about the difference between freeze-dried and dehydrated are from brands who want to sell you their freeze dryers or freeze-dried products.
A lot of them spout numbers about how much nutrients are retained and moisture removed, but without any info to back up these “facts.”
I dug in deep to honestly look at freeze drying vs. dehydrating. Here’s how they compare in terms of:
- Types of foods that can be dried
- Shelf life
Freeze Dried vs. Dehydrated Food Which is Best?
In terms of shelf life, freeze-drying is hands-down better than dehydrating. The process removes more moisture so the dried foods can last years or even decades if stored properly.
You can freeze-dry more types of foods, and they usually retain their quality better than dehydrated foods. However, dehydrating is much cheaper and easier, so is usually the better choice for people on a budget or taking the DIY approach.
Freeze drying is a reasonably new food preservation method that utilizes lyophilization: a process in which ice is turned directly into a gas. It involves freezing the food and then reducing the pressure in the chamber, which causes the ice to evaporate. You can read more about freeze-drying here.
Dehydrating is one of the oldest forms of food preservation. It is a straightforward process that uses heat to evaporate moisture from food. You can hang foods to dry or use the sun, an oven, or dehydrator machine.
Types of Foods that Can Be Dried
You can dry many more types of food with freeze-drying than dehydrating.
For example, it is possible to freeze-dry raw or cooked eggs in a freeze dryer. Dehydrating doesn’t work well with eggs because the proteins become too hard and chewy. The same is true with many raw vegetables.
Likewise, you can’t really dehydrate liquids like milk or yogurt because it is too messy and takes an extremely long time. With a freeze dryer, you could dehydrate all sorts of liquids to make your powdered milk, powdered coffee, etc.
For more about which foods can (and can’t) be dehydrated, read:
|Cooked carbs (rice, pasta, etc.)||Yes||Yes|
|Baked goods, pancakes||Yes||Some|
|Fatty foods (nuts, peanut butter, mayo, butter, etc.)||No||No|
Freeze drying typically removes more moisture than dehydrating. Because there is less water activity, freeze-dried foods have a longer shelf life than dehydrated foods.
However, the shelf life of freeze-dried foods is usually greatly exaggerated. Without special packaging, freeze-dried foods will typically last 6-12 months, whereas dehydrated foods last 4-12 months.
So why do people say freeze-dried foods can last up to 25 years?
This is the shelf life of freeze-dried fruits and vegetables with special packaging. This packaging is usually a Mylar bag or sealed can which has had oxygen removed from it (either with oxygen absorber packets or nitrogen flushing).
Because the freeze-dried food is protected from moisture and oxidation, the shelf life really can be 25 years (or longer).
Once you open the package, the freeze-dried food will be exposed to air. Oxygen will start breaking down the food. Moisture from the air will get absorbed into the food, and it could get wet enough for microbes to grow.
That’s why the shelf life of freeze-dried foods in normal packaging conditions is only 6-12 months.
Dehydrated foods can also be packed with oxygen absorbers.
You can also package dehydrated foods in Mylar bags with oxygen absorbers. Packaged like this, many dehydrated fruits and vegetables can last 10 to 15 years.
The catch is that you need to make sure the dehydrated foods are very dry. Many store-bought dehydrated foods aren’t dry enough to be stored this way.
You’ll have to take the DIY approach and make sure you leave the foods in the dehydrator for long enough. As a general rule, for long-term storage, dehydrated foods need to be so dry that they snap when bent.
Also Read: How Long Do Dehydrated Foods Last?
Shelf Life Comparison of Freeze-Dried vs. Dehydrated
|Dehydrated Fruits/Veggies||Freeze Dried Fruits/Veggies|
|Conventional Packaging||4-12 months||6-12 months|
|Packaged with Oxygen Absorbers||10-15 years||25 years|
Both freeze-drying and dehydrating preserve fiber and minerals like calcium and iron in food. Nutrients like vitamins and antioxidants are more sensitive, though, and some are lost during the process.
Because dehydrating uses heat and freeze-drying does not, more nutrients are retained with freeze-drying than dehydrating.
However, the nutritional difference is not that significant in real-world conditions!
A lot of websites say “freeze-dried foods retain up to 97% of their nutrition” compared to just “40%” or “60%” with dehydration. It is unclear where they are getting these facts since no studies are mentioned. It seems that one website quoted these numbers, and other websites just copied them.
With some digging, it isn’t that difficult to get actual stats on how many nutrients are retained.
For example, this study found that freeze-drying causes a 37% drop in vitamin C levels in tropical fruit, whereas dehydrating causes 49% losses.
Another study found that freeze-drying caused a 21% drop in vitamin C levels compared to a 64% loss in dehydrated fruit.
Nutrition Will Drop in Storage Anyway
It’s worth noting that many vitamins – especially vitamin C – are susceptible to heat, light, and oxygen. Even if you store your dried foods carefully, these vitamins will break down anyway. The same applies to antioxidants, enzymes, and many other nutrients.
Long-term, the fact that “freeze-drying preserved X amount of nutrients versus Y amount with dehydrating” won’t really matter.
Also read: Are Dehydrated Foods Good for You?
Dehydrating causes food to shrink as it dries. It gets a leathery feel and chewy texture.
By comparison, freeze-dried foods do not shrink as they dry. They end up crunchy and crispy.
Neither is better: some people prefer snacking on chewy dehydrated apples, whereas others love crispy freeze-dried ones. However, freeze-drying is usually better than dehydrating at preserving flavor and color.
It is easier to rehydrate freeze-dried foods than dehydrated foods. The freeze-drying process doesn’t cause the food to shrink, and there are many air pockets within the food. These air pockets mean the freeze-dried food can easily absorb water. Some foods rehydrate into almost their original state.
By contrast, most dehydrated foods will never rehydrate back into their normal state.
Dehydration causes foods to shrink and become very dense. The density means that the dry foods won’t absorb water well. It can take hours of boiling to rehydrate fibrous foods like raw vegetables (which is why you should cook most veggies before dehydrating).
Dehydrated foods are much cheaper than freeze-dried. Store-bought dehydrated strawberries can easily be found for $0.60 per ounce. Freeze-dried strawberries in similar packaging cost at least $3 per ounce – which is 5x more.
Even the DIY approach will cost much more. A small freeze dryer machine costs thousands of dollars. By contrast, even high-end dehydrators usually don’t cost more than $300. You can find some models for incredibly cheap or even make a dehydrator for free.
Freeze drying machines also use at least twice the amount of electricity per hour as dehydrator machines. There are also costs of maintaining the freeze dryer, like replacing oil.
If you want to stockpile food for emergencies, it doesn’t get easier than buying freeze-dried foods. The best emergency food brands pack their freeze-dried foods, so they last 15-25 years. There are no brands selling dehydrated food with comparable shelf lives.
But, if you want to take the DIY approach to food storage and don’t necessarily need a 25-year shelf life, dehydrating is more convenient than freeze-drying. Dehydrators are easier to use, take up less space, are faster and quieter. Here is how it breaks down.
|Size of Typical Machine||19x17x13||18x22x29 inches|
|Noise||0-65 decibels||65 decibels|
|Batch Time||1-24 hours||20-40 hours|
The bottom line?
If you are stockpiling food long-term, it’s likely worth the cost of buying a freeze dryer or buying from emergency food brands. If you just want a way to preserve fruits and veggies longer, then dehydrating is the way to go.