Dehydrating and freeze-drying are two very popular methods for food preservation. They offer similar results and shelf-stable products, but how are they different, and which is better for your situation? In this article I get into dehydrating vs. freeze drying, so you can figure out which option is best for you.
The main difference between dehydrating and freeze-drying is moisture. Dehydration reduces the moisture content of your food to between 5 and 20%. This moisture reduction causes food shrinkage, resulting in smaller storage space and greater preservation. Freeze drying food is the process of freezing moisture content out of your food. Freeze-drying preserves your food’s size, color, and nutrition while extending its lifespan.
|Cost||Less expensive||More expensive|
|Food Preservation Efficacy||Reduces size & sometimes the nutritional value of the food.||Best at preserving flavor, color, and nutrition.|
|Food Shelf-Life||Shorter shelf-life||Longer shelf-life|
|Methods||Sun-drying, Air drying, Oven drying, Electric dehydrating, Microwave||Freeze drier, Freezer Dry ice, Vacuum chamber|
|Cons||Weight gain, Vitamin deficiencies, Dehydration||Expensive, Learning curve, Takes up space|
While the two offer similar results, there are very different benefits to each method and other negatives.
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The dehydration process reduces the moisture content of your food to between 5 and 20%. The bacteria that cause food to decay cannot survive in this range. Therefore, by removing moisture from food, you extend its lifespan.
It is an ancient method of food preservation. Water is extracted from the food through the sun or machine drying. The food is thereby reduced in size, requiring less storage space. It preserves well for longer, making it ideal for emergency food storage. Additionally, it’s one of the top go-to foods for hikers and backpackers.
Types of Dehydration
There are several different types of dehydration, and some methods are more successful than others. These are the most common food dehydration methods used today:
Sun-drying is the oldest and simplest food preservation method. Anywhere with a minimum temperature of 86℉ and relative humidity of 60% is sufficient. Fruit does take several days to dry thoroughly. You will need to place it on a mesh screen but avoid anything that is galvanized. Then cover it with another screen to keep bugs away.
2. Air Drying
Air drying typically takes place in the shade, differentiating it from sun drying.
This method works well for anything that needs protection from the sun’s rays.
3. Oven Drying
Oven drying uses your home’s oven to dry food, and it works at temperatures of 140℉. However, due to the size of the range, it is not the most efficient tool to dry food.
Additionally, using your oven will warm your house as you will have to keep the door propped open to release the moisture.
You will need to ensure that your oven’s temperatures go low enough. Anything above 140℉ will cook your food, not dry it.
Another problem with oven drying is that you can’t use your oven for anything else while dehydrating food. Since dehydrating food takes a long time, using your oven to dehydrate food can be a major inconvenience.
4. Electric Dehydrating
Electric dehydrators are equipped with fans and heating elements that quickly and efficiently dry your food. Most dehydrators also come equipped with a temperature gauge and an adjustment dial, which assists with the speed up (or slow down) of drying time depending on what you are processing.
If your dehydrator has a fan, you can use it in your garage so that you do not have to listen to the noise of its operation. However, most dehydrators are quiet enough that the sound of the fan shouldn’t disturb you much.
Since electric dehydrators put out some heat, you may want to move them into the garage to avoid heating your house in the summer. On the other hand, the small amount of heat an electric dehydrator generates is a nice bonus in the winter!
5. Dehydrating Food in a Microwave
You can even dehydrate in your microwave. Using the defrost setting, you can dehydrate most fruits in 20 to 40 minutes. You will have to keep checking on them to ensure that you do not overdo it. You can also dehydrate herbs, but this will only take an average of 2 to 3 minutes.
Cons of Dehydrating Food
Dehydrated foods are a great source of nutrients; however, they are highly concentrated in calories and sugar. Because the serving sizes are smaller after dehydration, overeating can be a problem.
Let’s take a closer look at the cons of dehydrating food:
1. Unwanted Weight Gain
Depending on the food, dehydrated foods have higher calorie, sodium, and sugar contents.
In excess, these foods can contribute to unwanted weight gain, increasing your risk of obesity, heart problems, and diabetes.
Pro tip: Since dehydrated food has shrunk down a lot, simply eat less. As an example, raisins are dehydrated grapes. Instead of eating the same volume as a big bunch of grapes, eat just a tablespoon or two of raisins.
2. Vitamin Deficiencies
Vitamins A, B, and C may be reduced or destroyed through dehydration.
If you depend on your dehydrated food for these nutrients, you may find yourself in a deficiency.
Pro tip: Heat is one of the biggest culprits when it comes to nutrient loss. Except for foods such as meat that needs to be dehydrated at 160 degrees, to retain as many nutrients as possible, dehydrate food at a lower temperature. Food is actually considered “raw” if it is dehydrated at a temperature of 115 degrees or lower.
It does take more time to dehydrate food at a lower temperature, but if retaining as many nutrients as possible is your goal, then it’s worth setting the temperature on your dehydrator to 115 degrees.
Make Up for Nutritional Loss by Growing Sprouts and Microgreens
In addition to that, I recommend including sprouts and microgreen seeds in your prepper pantry. Sprouts and microgreens grow super fast, and since you eat them fresh, they are highly nutritious. I find them to be the best way to add fresh food to your prepping plan.
To learn more about this topic, read my article, Why Every Prepper Should Add Sprouts and Microgreens to Their Prepper Pantry.
Because most people do not drink enough water, consuming dehydrated foods may contribute to dehydration.
You will have to supplement your water intake with other foods with high water content, or drink plenty of water if eating a lot of dehydrated food.
Freeze drying food uses a process that lowers the temperature of the food to below freezing, and then a high-pressure vacuum extracts the water vapor.
The vapor collects on a condenser, turns back to ice, and is removed. A gradual temperature increase extracts all remaining moisture from the food.
Through this process, the structure of the food is maintained, while flavor, color, and nutrition are all preserved. Your food is now ready to be rehydrated at a later date.
Foods can dry at low temperatures without causing damage to their structures. Freeze-dried foods do not require refrigeration or preservation by chemicals, and you can quickly reconstitute them with water.
Its advantage over conventional drying methods is that these methods use high temperatures that can cause chemical or physical changes. This results in a change in the taste or texture of the food.
Freeze Drying Methods
There are several methods that you can choose from to freeze-dry your foods.
1. Using a Freeze Dryer
You will want to place your food in the freeze-drying trays, making sure to not exceed the height of the tray.
Place the food-filled trays in the dryer and close the door.
Freeze the food at -40 to -50℉, allowing 24 hours for the process to finish. Place the food in mylar bags for storage.
Pro Tip: Using a freeze dryer is by far the safest, most efficient, and only way to reliably freeze dry food at home. The best company to purchase a home freeze dryer from is Harvest Right.
Learn more about freeze drying in my article, Adding Freeze Dried Food to Your Prepper Pantry.
2. Using Your Freezer
This method is a little more time-consuming.
You will need to place the food on a tray, spreading it out. Then, place the tray in the freezer at the lowest possible temperature.
Allow the food to remain in the freezer until it is entirely freeze-dried, approximately 2 to 3 weeks. Once finished, store it in an airtight container in your pantry.
Since home freezers aren’t intended for freeze drying food, I personally don’t recommend this option since it could be hard to know for sure if the food you’ve freeze dried in this manner is truly shelf stable.
3. Using Dry Ice
You can also use dry ice, which is much faster than a traditional freezer.
Pack the food in freezer-safe bags and put them in a cooler. Fully cover the bags with dry ice and keep them there for 24 hours.
Then store the bags in the pantry.
Again, this is not the preferred method of freeze drying, since it’s harder to regulate compared to a device actually intended for freeze drying.
4. Using a Vacuum Chamber
While it is the most expensive method, a vacuum chamber is also the most efficient.
A special chamber freeze-dries the food, and it is specially designed to speed up the process.
Cons of Freeze Drying
While freeze-drying offers some great benefits, it also has some negative points:
- The equipment needed for this process is way more expensive than dehydrating food.
- Freeze dryers take up a lot of space, and are noisy. You also need to have a lot of space in your regular freezer to freeze food before putting it on a freeze dryer.
- Additionally, freeze-dried foods take up just as much space as fresh foods. This is one of the biggest cons in my opinion, because unless you have a lot of storage space, you won’t be able to store a lot of freeze dried food.
Conclusion: Difference Between Freeze Drying and Dehydrating
Freeze drying methods tend to be more expensive than dehydrating methods. However, they are better at preserving flavor, color, and nutrition. Freeze-dried foods tend to last longer than dehydrated foods as well.
Dehydration reduces the size and sometimes the nutritional value of the food. For the most part, the food is nutritionally preserved, just at a smaller size.
The two processes result in very similar results. The choice of which method to use is really up to you, as they are both excellent options. Using one over the other usually comes down to preference, cost, and purpose.
Recommended Resources for Dehydrating and Freeze Drying
Here’s a short list of what I recommend if you want to dehydrate and/or freeze dry food.
Electric Dehydrators: I use both the Nesco and Cosori Dehydrators. If you prefer to buy American, then the Nesco is the way to go. If you have the budget for it, then Excalibur dehydrators are another great American made option. They have a stellar reputation, and you can dehydrate a lot of food in a small area.
Home freeze dryer: Even though I presented a few options for freeze drying in this article, using an actual freeze dryer is the only way I recommend. Harvest Right is THE company for home freeze dryers.
The Ultimate Dehydrator Cookbook is, in my opinion, the best book on home dehydrating out there. If you only buy one book related to dehydrating, this is the one to buy. You can buy it here, on Amazon.
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