Freeze Drying vs. Dehydrating: What You Need to Know

Preserving food will allow you to save money, reduce food waste, and prepare for emergencies. 

To learn more about freeze-drying and dehydrating food, continue reading below. 

What is Freeze Drying?

Freeze drying is a food preservation method that involves freezing food and then removing water through sublimation. Sublimation is when water changes from solid straight to gas without passing through the liquid state.

Freeze drying is a relatively new method of food preservation, but it has become very popular in recent years.

Pros and Cons of Freeze Drying

When considering freeze-dried foods vs. dehydrated foods, you should know the pros and cons of each. Below are the advantages and disadvantages of freeze-dried foods.

A few of the advantages of freeze-drying foods are: 

• Retains Nutrients: One of the main benefits of freeze-drying is that it preserves most of the nutrients, flavor, color, and texture of food. Unlike other methods that use heat or chemicals, freeze-drying does not alter the chemical structure or degrade the quality of food. Freeze-dried foods taste almost like fresh food when rehydrated.
• Extends Shelf Life: Another benefit of freeze drying is that it extends the shelf life of food up to 25 years or longer. Since freeze-drying removes almost all the moisture from food, it prevents the growth of bacteria, mold, and yeast that can spoil food. Freeze-dried food can be stored at room temperature without refrigeration or freezing.
• Easy to Rehydrate: A third benefit of freeze drying is that it rehydrates easily and quickly with water. Freeze-dried food can be ready to eat in minutes by adding hot or cold water. This makes it convenient for camping, hiking, emergency situations, or everyday use.
• Versatile Preservation Method: A fourth benefit of freeze drying is that it can be done with different kinds of food like fruits, vegetables, meat, and dairy. Freeze-drying preserves the natural shape and color of food, making it appealing and appetizing. Freeze drying also allows for mixing and matching different ingredients to create customized meals.

A few of the disadvantages of freeze-drying foods are:

• High Cost: One of the main drawbacks of freeze drying is that it requires a special piece of equipment called a freeze dryer, which can be bulky and expensive. A home freeze dryer can cost anywhere from $2,000 to $6,000, depending on the size and capacity. A commercial freeze dryer can cost much more. Freeze dryers also need regular maintenance and cleaning to function properly.
• Long Wait Time: Another drawback of freeze drying is that it takes up a lot of energy and time to complete the process. Depending on the type and amount of food, freeze-drying can take from 24 to 48 hours or more. Freeze dryers also consume a lot of electricity, which can add up to the cost of operation.

Ways to Freeze Dry

There are three main methods you can use to freeze dry food: using a freeze dryer, using dry ice, or using a freezer.

Using a Freeze Dryer

A freeze dryer is a machine that freezes food and makes a vacuum to remove the water through sublimation. Freeze dryers come in different sizes and capacities to fit your needs. To use a freeze dryer properly, follow these steps:

1. Prepare your food by washing, slicing, peeling, or cooking as needed.
2. Put your food on trays inside the freeze-dryer chamber.
3. Set the time and temperature according to your freeze dryer’s user manual.
4. Wait for the freeze dryer to complete the cycle. This can take a few hours or a few days, depending on what kind of food you’re drying.
5. Remove the food from the trays and keep it in airtight containers with oxygen absorbers. 

Using Dry Ice

Dry ice is basically frozen carbon dioxide that sublimates at room temperature. If you don’t want to use a machine, you can use dry ice to freeze dry food. But you’ll need to be careful when you handle it since it can cause frostbite. To use dry ice safely, follow these steps:

1. Prepare your food by peeling, washing, slicing, or cooking as needed.
2. Put your food in freezer bags and squeeze out as much air as you can.
3. Put a layer of dry ice in a cooler or a big container with a lid.
4. Put your food bags on top of the dry ice layer and cover them with another layer of dry ice.
5. Shut the lid tightly but not completely, allowing some gas to escape.
6. Wait for 24 hours or until all the dry ice has sublimated.
7. Remove your food bags from the cooler and keep them in airtight containers with oxygen absorbers.

Using a Freezer

Another method you can use to freeze dry food is by using a freezer. You can use a regular freezer to freeze dry food, but it’ll take longer and might not be as effective as using a freeze dryer or dry ice. If you opt to use a freezer, follow these steps: 

1. Prepare your food by washing, peeling, cooking, or slicing as needed.
2. Put your food on baking sheets or trays in one layer.
3. Place your trays in the freezer and set the temperature to the lowest possible setting.
4. Check your trays every couple of hours and flip your food over to expose all sides to the cold air.

What is Food Dehydration?

Food dehydration is a process that involves using air movement, heat, and dry air to remove water from food. Dehydrating can remove up to 95% of water in food.

This is a traditional food preservation method that has been practiced for centuries by cultures all over the world.

Pros and Cons of Dehydrating

Dehydrated foods come with their own benefits as well as downsides; below is what you should know about dried foods.

Some of the advantages of food dehydration are:

• Affordable Price: Compared to a freeze dryer, a food dehydrator is relatively cheap and widely available. You can find a food dehydrator for as low as $50. However, for better working, and more efficient food dehydrators, you will likely have to spend upwards of $150. However, you can also rely on sun-drying or an oven to dehydrate fruits and vegetables.
• Reduces Weight of Food: Since much of the water is removed in the dehydration process, it reduces the weight and size of the dehydrated foods. This makes food storage, as well as storing food for backpacking and camping, much easier.
• Enhances Flavor: Dehydration improves the flavor and sweetness of dry fruits by concentrating the natural sugars.
• Versatile Method: Food dehydration can work on lots of different foods, even those with low water content.

Some of the disadvantages of dehydration are:

• Reduced Nutrients: In the food dehydration process, some of the nutrients can be lost due to heat exposure. This is not the case in the freeze-drying process.
• Longer Rehydration: To rehydrate dehydrated foods, you may find yourself waiting much longer. But this depends on the food itself.

Ways to Dehydrate Food

There are four main ways to dehydrate food: oven drying, air drying, sun drying, and electric drying.

Oven Drying

Oven drying uses your home oven to slowly dry food at around 140 degrees Fahrenheit. To use an oven to dehydrate food, follow these steps:

1. Prepare your food by washing, peeling, slicing, or cooking as needed.
2. Put your food on baking sheets or trays.
3. Set your oven to a low temperature possible. Ideally, set your oven to 140F or lower.
4. Prop the oven door open slightly to let moisture escape.
5. Check on the food every hour and flip it over to ensure even drying.
6. Wait for six to ten hours, depending on the type and thickness of your food. 

Sun Drying

Sun drying requires higher temperatures and lower humidity. If you want to sun dry your food, follow these steps:

1. Prepare your food as needed.
2. Put your food on mesh screens or trays.
3. Cover your food using cheesecloth or thin fabric to protect it from dust and bugs.
4. Put your screens or trays in a sunny space with good air circulation. Ideally, the space should be hotter than 95 degrees Fahrenheit and should have a relative humidity of 60% or less.
5. Check your food every few hours and rotate your screens or trays as needed.
6. Wait a couple of days until your food is dry and brittle.

Air Drying

To air dry your food, follow this procedure:

1. Prepare your food by peeling, washing, cooking, or slicing as needed.
2. Put your food on racks.
3. Hang your racks in a cool, dry, well-ventilated area far from direct sunlight and sources of moisture or heat.
4. Check your food every day and get rid of any moldy or spoiled pieces.
5. Wait for a few weeks until your food is dry and leathery.

Electric Food Dehydrator (Electric Drying)

Electric drying makes use of a dehydrator machine that uses a heating element and a fan to circulate hot air around the food. Electric dehydrators can have different features and sizes depending on your needs. Follow these steps to use one:

1. Prepare your food.
2. Put your food on dehydrator trays in a single layer without overlapping.
3. Set the temperature and time according to the manufacturer’s instructions.
4. Wait for your dehydrator to complete the cycle. This can take a few hours or a few days.
5. Remove your food from the trays and store it in airtight containers with oxygen absorbers.

Comparison: Freeze Drying vs. Dehydrating

Now that we’ve seen how the freeze-drying and dehydrating methods work let’s compare them in terms of a few important factors. Here is a quick summary of our findings:

Equipment Required

One factor to consider is the equipment required for each method. For example, freeze-drying may require a freeze-dryer. This piece of equipment can be bulky and expensive, upwards of $2,000. Of course, you can freeze dry using dry ice or a freezer, but doing so may not be as effective. 

On the other hand, you can dehydrate food with or without a dehydrator. You can use your own oven or rely on natural sun or air drying. However, these methods might not be as reliable as using a dehydrator.

Energy and Time Consumption

Another factor to consider is how much energy and time are required for each method. Freeze drying takes a lot of energy and time to complete. It may take several hours or days, depending on the type and amount of food. 

On the other hand, dehydrating consumes less energy and time than freeze drying. Of course, this will depend on the freeze-drying method and the type and thickness of the food. 

Nutrition

A third factor you should consider is the nutrition of the food after using each method. Freeze-dried food retains most of its nutrients, flavor, color, and texture. It can do this because it removes water without using heat or light. 

Conversely, dehydration may cause some loss of nutrients, color, flavor, and texture. This is because dehydration uses heat and light, which can degrade some vitamins and minerals in food. However, dehydration concentrates the natural sugars in food, which can sometimes enhance the flavor and sweetness of certain food.

Rehydration

A fourth factor you should keep in mind is the rehydration of the food after each method. You can rehydrate freeze-dried food easily and quickly using water. This is because the food will keep its original shape and structure after freeze-drying. 

Comparatively, dehydrated food will take longer to rehydrate and will need more water. This is because dehydrated food shrinks and becomes leathery after drying.

Texture

Another thing to consider is the texture of the food after using each method. Freeze-dried food produces crunchy and crispy food that you can eat as snacks. On the other hand, dehydrated food produces chewy and leathery food.

Shelf Life

The shelf life of freeze-dried foods can be as long as 25 years. Dehydrated foods have a much shorter shelf life of 2-3 years. Still, both are much longer than the few weeks or months foods will last without preserving food long term.

Variety

The final factor you should consider is the variety of food that you can treat with each method. You can use freeze-drying with various types of food, including fruits, vegetables, candy, meat, and dairy. This is because it removes water without affecting the composition of the food. 

Dehydrating, on the other hand, mostly favors low water content food like meat, fruits, and vegetables. This is because it uses heat to remove water, which can affect the structure of high-water-content food.

Final Thoughts

Food dehydration has a much longer history than freeze-drying, but in recent years the freezing-drying method of food preservation has become very popular. And for good reason.

Both methods allow for similar benefits:

• Extend the shelf life of food items
• Enhance the flavor of food
• Reduce the size and weight of food

However, there are some unique benefits to freeze-drying that make us think it is a better food storage method. For starters:

• Food is preserved for up to 25 years
• The nutrients are retained
• It is easier to rehydrate

Still, there is a major downside to using a freeze dryer, and that is the price. The high equipment cost and energy demand make using a freeze dryer expensive and difficult to access for most people.

So for everyday usage at home, it makes more sense to use an electric food dehydrator. A food dehydrator can be purchased for as low as $50. A food dehydrator makes food preservation easy and affordable for most people.

Still, freeze-drying and dehydrating are two effective methods of long-term food preservation that have their own pros and cons. Depending on your needs, budget, and preferences, you may choose one over the other.

To learn more about food preservation, check out the other blog posts on our website. 

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