What Is Freeze-Drying: A Full Guide on Freeze-Dried Products

November 3, 2023
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Preserving food and extending its shelf life has always been important. That’s why there are various food preservation methods available. In the past decade, freeze-drying has become especially popular. Even though it’s not suitable for all products, it has many applications in pharmaceuticals, the restaurant industry, and the food and beverage industries. In this guide, we’ll give information on all important aspects of freeze-drying. So if you want to know what is freeze-drying or what products can you dehydrate with the help of this method, you’re at the right place.

What Is Freeze-Drying

It is often referred to as lyophilization. This process removes around 99% of the water content of products. That way, bacterial growth practically stops. The shelf life of freeze-dried products is extended significantly. If stored properly, products that have gone through this process can be safely consumed even after decades.

Freeze-drying has other applications as well. It’s used by pharmaceutical companies to extend the useful life of vaccines or some drugs. The method can be used by taxidermists for preserving various animals.

Unlike other food preservation methods, proper freeze-drying can only be done in a specialized freeze-dryer machine. 

Freeze-Drying Process

  1. Freezing. As its name implies, the first step of the process is to freeze the products in the freeze-dryer’s chamber. The machine reduces the temperature to −30 °F. Some commercial dryers can lower the temperatures even further to −110 °F.
  2. Vacuum. When the water molecules in products are already frozen, the pressure in the chamber is reduced. By creating a vacuum, the ice crystals can be evaporated instead of liquefied.
  3. Sublimation. As the temperature and pressure have been lowered, the machine will start to slowly introduce heat in the chamber. That will result in a sublimation where the frozen water molecules inside the products will turn directly into vapor instead of liquid.
  4. Further dehydration. During the initial dehydration process, most of the water content is removed. However, in order for the products to lose almost all water molecules, a second dehydration stage is necessary.
  5. Storage. After the items are removed from the freeze-dryer’s chamber, they need to be stored properly. If certain storage conditions are not met, their shelf life will still be increased by a couple of years, but they might be prone to bacterial growth if they are in contact with air or moisture. That’s why it’s recommended to put these dehydrated products in airtight containers or sealable mylar bags.

Freeze-Dried Food

The reason why this food preservation method has become so popular is the fact that it’s a popular food trend right now. Many buy residential freeze-dryers and experiment with different products. Business owners utilize the popularity of this method and implement it in restaurants or other food service establishments. It can also help significantly with waste reductions as the shelf life of freeze-dried products is increased drastically. That’s why restaurant managers should also consider investing in such equipment.

Popular Food Products to Freeze-Dry

  • Vegetables. Peas and peppers are among the most common vegetables that can be dehydrated with this method. They can be used for cooking.
  • Fruits. Apples and berry fruits can also be dried and used for dessert recipes. Alternatively, many people who enjoy this dehydration method consume the products without rehydrating them. They become a delicious and crunchy snack.
  • Meat. Hikers often purchase freeze-dried products for their trips. Beef and chicken are among the most popular options. Cooked meat should be sliced before the dehydration process begins in order to guarantee that all water molecules will be removed. 
  • Candy. Owners of freeze-dryers experiment by dehydrating various candy brands. During the process, their texture might change significantly. For example, gummy candies increase their size and become crunchy. Usually, dehydrated candy cannot be rehydrated without losing its texture and is consumed in its crunchy form.
  • Beverages. Wholesale coffee distributors offer a variety of freeze-dried coffee options. They are more commonly known as instant coffee. Other drinks that can be dehydrated and turned into powder include tea, milk, and juice.
  • Other cooked meals. Scrambled eggs and pasta are just a few examples of meals that can be dehydrated and stored in airtight containers.

Pros and Cons of Freeze-Drying Food

There are various reasons for the rise in popularity of this method. Allow us to briefly share the main pros of freeze-drying.

  1. Products that have been dehydrated through this method are lightweight and easy to store. That lowers transportation costs for wholesale food distributors that deliver freeze-dried goods;
  2. Freeze-drying retains all nutrients;
  3. The shelf life of the products is significantly increased;
  4. Most products that have been dehydrated with this method can easily be mixed with water or through exposure to moisture.

As with most things in life, there are also cons to this method. Here are some of them.

  1. Unlike dehydration, freeze-drying requires specialized equipment which can be costly;
  2. There are many food products that cannot be preserved by freeze-drying them;
  3. Freeze-dried items need to be stored in airtight containers which can be inconvenient.

Freeze-Dried Drinks

Although freeze-drying is mostly popular for food and candy, it can be used for beverages as well. Unlike other dehydration methods where the beverages are turned into a concentrate, with freeze-drying they become solid like powder. In order to rehydrate them, you just need to mix them with water or other substances with high moisture content such as yogurt. 

Popular Freeze-Dried Drinks

  1. Instant coffee. The process of making instant coffee includes dehydrating the beverage in order to turn it into powder.
  2. Tea. You can also freeze-dry tea. It can be then rehydrated and enjoyed as a beverage or used for cooking and baking.
  3. Juice. This dehydration technique can be used not only for fruits but also for their juice. 
  4. Milk. When freeze-dried, milk becomes like powder too. It’s important to keep in mind that not all varieties of milk can go through this process. Some plant-based milk varieties that are rich in fat cannot be freeze-dried.
  5. Soup. You can easily create soup mixes at home with the help of a freeze-dryer. The machine removes the water content and leaves a powder-like substance. Mixing it with water and adding some additional ingredients will result in a tasty meal.

Businesses can use freeze-dried drinks for a variety of reasons. For example, they can be used by smoothie bars or by smoothie manufacturers. Using freeze-dried ingredients instead of fresh ones means these businesses can cut transportation and storage costs. 

Another application of freeze-dried beverages is in the alcohol industry. Distilleries might purchase concentrated forms of juice to produce flavored liquor or hard seltzers.

Adapting to the latest trends is important for businesses. That’s why they can benefit from introducing healthy snack ideas or mocktail drinks made with freeze-dried ingredients.

Freeze-Dried Fruits

Most owners of home freeze-dryers frequently use their machines to dehydrate fruits. After they go through this process, fruits become crunchy and even more delicious. Allow us to briefly share more information about the most common fruits you can freeze-dry.

  1. Berries. A crunchy and delicious snack, berry fruits are among the most popular things to freeze-dry. They can also be used for recipes like bowls or desserts. They are usually rich in fiber and can be used to make granola bars.
  2. Apples. Dehydrated apple slices can be used as a trail snack or for decoration of plates or the interior.
  3. Bananas. If you enjoy chips but also want to be healthy, you might want to try banana chips.
  4. Citrus fruits. Oranges, lemons, and lime can be dehydrated and turned into sour snacks. Alternatively, they can be mixed with water to achieve a refreshing fruit-infused beverage.

Fruits That Shouldn’t Be Freeze-Dried

Even though a lot of products can be dehydrated through this technique, there are some limits to the method. Let’s briefly dive into the fruit items you should avoid freeze-drying.

  • Oily fruits. If freeze-dried, these products will not become crunchy as the method cannot remove the fat content, only the water. Examples in this category include avocados and olives.
  • Jams. Fruits that have gone through other food preservation methods should not be freeze-dried as well. The high sugar content will make them sticky instead of crunchy.
  • Nuts. Some nuts can be freeze-dried but those that are rich in fit are not protected from going rancid.

Freeze-Dried Candy

The main reason for the popularity of freeze-dried products in recent years is the trend to dehydrate candy with this method. Owners of home freeze-dryers enjoy experimenting with various candy brands. What is specific about these products is that most of them cannot be rehydrated. Instead, they are consumed as snack food in their crunchy and delicious freeze-dried form. 

During the freeze-drying process, most candies change their texture significantly. Some of them, like gummy candy brands, get much larger. Not all candies can be freeze-dried though. That is why people often experiment with their freeze-dryers in order to see which ones are suitable for this method.

Popular Freeze-Dried Candy

  • Marshmallows. The freeze-drying process changes their texture. They become crunchy and hard. In that state, they can be used as a hot beverage topping or enjoyed as snacks.
  • Gummy candy. Whether it’s gummy worms or other forms, these candies significantly change their structure. Their size increases and they become similar to corn puffs. They can be crushed and powdered in order to be used as decoration.
  • Skittles. During the process, their shell might crack to allow water content to escape.

Freeze-Drying Machines

One of the drawbacks of freeze-drying is the fact that you need specialized equipment to do it. Freeze-dryers can be expensive and it might not be worth the investment if they’re not used regularly. At the beginning of this article, we explained the steps of the process and how a freeze-dryer works. So, allow us to give some additional details on the different types of machines.

  • Home freeze-dryers. If you’ve watched videos or posts on social media about freeze-dried products, you’ve likely seen these machines. They are similar to a washing machine in size and appearance. The smallest varieties can dehydrate about 5 pounds while the biggest home freeze-dryers can freeze-dry around 20 pounds per cycle. These machines can also be used in businesses such as coffee shops or restaurants.
  • Commercial freeze-dryers. As freeze-dried products become trendy, these machines are often part of the restaurant’s technology. Commercial freeze-drying dehydrators have a capacity between 20 and 100 pounds. Some eCommerce businesses that trade various dehydrated products also use such machines.
  • Industrial freeze-dryers. That category is used by manufacturers in the beverage industry or other large businesses that freeze-dry many products. Their capacity is usually above 500 pounds and it can go as high as a couple thousand pounds.

Freeze-Dryer Power Consumption

Generally speaking, a home freeze-dryer consumes around 1000 watts per hour. Small commercial ones can consume around 1500 watts while large ones can consume more than 2000 watts. That means that a single freeze-drying cycle will cost you around $10.

Freeze-Drying Machine Cycle

The machine needs between 20 and 40 hours to completely dehydrate the products. The time depends on factors such as the quantity and the type of products. If they are not prepared properly, it might take more time as well. Make sure to always prepare the products by slicing them or cutting them into smaller pieces. Otherwise, some of the water content might be trapped inside and the results will not be satisfactory.

Wholesale Freeze-Dried Products

With their rise in popularity, many wholesale produce distributors or wholesale coffee distributors have started offering such products. As freeze-drying equipment can be expensive, a lot of people buy such products instead of making them on their own. Let’s briefly examine some businesses that purchase wholesale freeze-dried products.

  • Food manufacturers. Freeze-drying is used for the production of instant soups or dehydrated snacks. That’s why food manufacturers might purchase freeze-dried wholesale candy or vegetables. This dehydration technique is also common for animal food products.
  • Retailers. Naturally, as freeze-dried products become more popular, retailers want to ride the trend wave and offer them in their stores. You can find various freeze-dried candy or beverages on the supermarket shelves.
  • Restaurants and coffee shops. Freeze-dried products can be used as ingredients in various baked goods or meals. Thus, restaurants might benefit from this popular trend and even use them as part of the restaurant’s marketing.

Freeze-Dried VS Dehydrated

Dehydration is one of the most common food preservation methods. When to freeze-drying, both techniques have their pros and cons. Let’s see what they are.

Pros of Freeze-Drying

  1. It increases the shelf life far more compared to regular drying;
  2. The majority of the nutritional value is preserved;
  3. It has more applications. You can freeze-dry candy and beverages. The method is also used by pharmaceutical companies.

Pros of Regular Drying

  1. It doesn’t require special equipment. You can dry food in an oven or just by exposure to the sun;
  2. The process is far simpler than freeze-drying.
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