We find great satisfaction in preserving our own food and storing a supply of shelf-stable food at our home. We use various food preservation methods including freezing and freeze drying foods. I was surprised to hear someone ask the other day, “Is freeze drying and freezing food the same thing?” The answer is no, freeze drying and freezing food are two different methods for preserving foods so that they can be stored long-term.
We use both methods, however, it is important to note that there are several big differences between the two food preservation methods. So what are the main differences between freezing and freeze drying food?
The main differences between freezing and freeze drying are that freezing involves lowering the temperature of food to below the freezing point of water to preserve it, while freeze drying removes the water from the food by sublimation, leaving behind a lightweight, shelf-stable product with a longer shelf life and better preservation of taste, texture, and nutritional value.
9 main differences between freezing and freeze drying include:
- Process: Freezing involves lowering the temperature of the food to below the freezing point of water (32°F or 0°C), while freeze drying involves removing the water from the food by sublimation.
- Equipment: Freezing can be done using a standard household freezer, while freeze drying requires specialized equipment, such as a freeze dryer or lyophilizer.
- Time: Freezing is a quicker process than freeze drying, which can take a day or more to complete.
- Cost: Freeze drying is generally more expensive than freezing, due to the cost of the specialized equipment and the longer processing time.
- Shelf life: Freeze dried products have a longer shelf life than frozen products, due to the removal of water, which is a key factor in the spoilage of food.
- Weight: Freeze dried products are much lighter than frozen products, due to the removal of water.
- Storage: Freeze dried products take up less space than frozen products, due to their lighter weight and smaller volume.
- Nutritional value: Freeze drying can help preserve the nutritional value of some foods better than freezing, due to the lower temperatures used and the shorter time the food is exposed to heat.
- Rehydration: Freeze dried products need to be rehydrated before they can be eaten, while frozen products can be thawed and eaten without further processing.
| Differences | Freezing | Freeze Drying |
| Process | Freezing involves lowering the temperature of the food to below the freezing point of water (32°F or 0°C). | Freeze drying involves removing the water from the food by sublimation. |
| Equipment | Freezing can be done using a standard household freezer. | Freeze drying requires specialized equipment, such as a freeze dryer or lyophilizer. |
| Time | Freezing is a quicker process. | Freeze drying can take a day or more to complete. |
| Cost | Freezing food is cheaper. | Freeze drying is generally more expensive due to the cost of equipment and time. |
| Shelf Life | Frozen foods have a much shorter shelf life. | Freeze dried products have a longer shelf life. Up to 30 years. |
| Weight | Frozen foods weigh more. | Freeze dried products are much lighter due to the removal of water. |
| Storage | Frozen foods take up more space and have limited storage in a freezer. | Freeze dried products take up less space due to their lighter volume and weight. |
| Nutritional Value | Frozen foods tend to lose their nutritional value quicker. | Freeze dried food tends to hold on to its nutritional value better and for longer. |
| Rehydration | Frozen products can be thawed and eaten without further processing. | Freeze dried products need to be rehydrated before they can be eaten. |
Freezing and freeze drying are two methods of preserving food that involves lowering the temperature of the food to prevent the growth of bacteria and other microorganisms. However, they differ in the way they remove water from the food.
Freezing involves lowering the temperature of the food to below the freezing point of water, which causes the water in the food to solidify into ice crystals. This can help slow down the growth of bacteria and other microorganisms, but it does not remove the water from the food.
Freeze drying, also known as lyophilization, is a more advanced process that removes the water from the food by sublimation, which is the process of turning a solid directly into a gas without passing through the liquid phase. The food is first frozen and then placed in a vacuum chamber, where the pressure is lowered to allow the ice to sublimate. The resulting process removes the water from the food and leaves behind a lightweight, shelf-stable product.
Freeze drying is more expensive and time-consuming than freezing, but it results in a product with a longer shelf life and better preservation of taste, texture, and nutritional value. It is often used for long-term storage of perishable foods, such as meats, fruits, and vegetables, as well as for the preservation of non-food items, such as pharmaceuticals and biological samples.
The Process of Freezing Food Versus Freeze Drying Food
Freezing food involves the following steps:
- Preparing the food: Wash and cut the food into appropriate sizes and shapes.
- Blanching (optional): Some foods, such as vegetables, may need to be blanched (briefly boiled and then chilled) to inactivate enzymes that can cause changes in texture, flavor, and nutrients during storage. For example see how to blanch corn before freezing it.
- Packaging the food: Place the food in airtight containers or bags and remove as much air as possible to prevent freezer burn. To help get longer storage life, consider using a vacuum sealer (see our top picks).
- Freezing the food: Place the packaged food in a household freezer set at 0°F (-18°C) or lower.
The process of freeze-drying food involves the following steps:
- Preparing the food: Wash and cut the food into appropriate sizes and shapes. See a complete list of foods can and cannot be freeze dried.
- Blanching (optional): Some foods, such as vegetables, may need to be blanched (briefly boiled and then chilled) to inactivate enzymes that can cause changes in texture, flavor, and nutrients during storage.
- Freezing the food: Place the food on a freeze dryer tray and in a freezer to be frozen.
- Loading the food into a freeze dryer: Place the frozen food in the freeze dryer and close the door.
- Turn on freeze dryer machine: Let the freeze dryer run through processes of freezing, removing the air, sublimation, and drying the food.
- Packaging the food: Place the dried food in airtight containers or bags and seal them to protect against moisture.
- Storing the food: Store the packaged food in a cool, dry place or in a vacuum-sealed bag or container.
See both methods in use by checking out our article on how to preserve and store pomegranates.
To follow the process above for freeze-drying food you will need to purchase a freeze dryer which can be quite expensive. We have a freeze dryer and use it frequently. Find out if buying a freeze dryer is worth it for you.
Differences in Equipment
Freezing food can be done using a standard household freezer, which is a common appliance found in most homes. A household freezer works by circulating cold air around the interior of the appliance, which lowers the temperature of the food to below the freezing point of water (32°F or 0°C).
Freeze drying, on the other hand, requires specialized equipment, such as a freeze dryer or lyophilizer. A freeze dryer consists of a vacuum chamber, a shelf or tray for the food, and a heating element. The food is placed on the shelf and the chamber is sealed and evacuated of air. The heating element is then turned on to warm the shelf and begin the sublimation process, which removes the water from the food. Freeze dryers can be large and expensive, and they are typically used in commercial food processing or research and development settings.
In summary, freezing food can be done using a standard household freezer, while freeze drying requires specialized equipment such as a freeze dryer.
Differences in Cost
Freeze dryers are generally more expensive than freezers. A freeze dryer can cost several thousand dollars, depending on the size and capabilities of the machine. In contrast, a household freezer can cost anywhere from a few hundred dollars to several thousand dollars, depending on the size and features of the appliance.
Freeze dryers are more expensive than freezers due to the advanced technology and specialized equipment required for the freeze drying process. Freeze dryers are typically used in commercial food processing or research and development settings, while freezers are more commonly used in households and small businesses for the storage and preservation of food.
In addition to the initial cost of the equipment, freeze dryers also have higher operating costs due to the energy required to run the machine and the cost of maintenance and repairs. Freezers, on the other hand, have lower operating costs, although the cost of electricity to run the appliance can vary depending on the size and efficiency of the freezer.
Overall, freeze dryers are generally more expensive to purchase and operate than freezers, but they can provide more advanced preservation capabilities and a longer shelf life for certain types of food.
Differences in Shelf Life
The shelf life of frozen food is generally shorter than the shelf life of freeze dried food.
Frozen food can be stored in a household freezer at a temperature of 0°F (-18°C) or lower for an extended period of time, but the quality of the food will begin to deteriorate over time due to the formation of ice crystals and the growth of bacteria and other microorganisms. The shelf life of frozen food can vary depending on the type of food, the storage temperature, and the packaging, but it is generally between several months and a year for most foods.
Freeze dried food, on the other hand, has a much longer shelf life due to the removal of water by sublimation. Freeze dried food can be stored at room temperature in a sealed container or bag for several years, depending on the type of food and the storage conditions. The lack of water in the food helps to prevent the growth of bacteria and other microorganisms, which allows the food to retain its quality and nutritional value for a longer period of time.
Overall, freeze dried food has a much longer shelf life than frozen food due to the removal of water and the reduced risk of spoilage.
Differences in Storing Frozen and Freeze Dried Foods
Frozen food and freeze dried food are stored differently due to their different physical properties and preservation methods.
Frozen food is stored in a household freezer at a temperature of 0°F (-18°C) or lower. It is typically packaged in airtight containers or bags to prevent freezer burn and to reduce the risk of contamination. Frozen food should be stored in the back of the freezer, where the temperature is most consistent, and should be rotated to ensure that the oldest food is used first.
Freeze dried food is stored at room temperature in a sealed container or bag. It does not require freezing, as the water has already been removed from the food by sublimation. Freeze dried food can be stored in a pantry, cupboard, or other dry, cool place, as long as it is protected from moisture, light, and heat.
In summary, frozen food is stored in a freezer at a low temperature, while freeze dried food is stored at room temperature in a sealed container or bag.
Differences in Nutritional Value
Generally, freeze dried foods retain their nutritional value better and for longer than frozen foods. However, It is difficult to say definitively which type of preserved food, frozen or freeze dried, retains its nutritional value better, as it depends on a number of factors, including the type of food and the storage conditions.
In general, both freezing and freeze drying can help preserve the nutritional value of some foods, particularly when compared to other preservation methods such as canning or drying. However, the specific nutrients and their levels can vary depending on the type of food and the preservation method.
Keep in mind, with frozen foods prolonged storage at low temperatures can cause the nutritional value of some frozen foods to decline, due to the formation of ice crystals and the exposure of the food to heat during the thawing process.
Freeze drying uses lower temperatures and shorter exposure to heat than other methods, which can help preserve the nutritional value of the food. However, the nutritional value of freeze dried food can also be affected by the length of storage and the conditions under which the food is stored.
