How often have you gotten the chance to pick the fresh fruit or berries and eat them right away? The fresh product often loses a large number of benefits during the time it ships to the country of destination. But there’s a solution to this problem!
Have you ever heard of freeze-drying food? Have you ever wondered why freeze-dried goods are even healthier sometimes than fresh alternatives from your local store? Though freeze-drying seems like a relatively new trend in food processing, it is quite an old technique, and it is still considered one of the most effective food preservation methods today.
What you will find in this article:
- Freeze-drying is considered the most successful method for food preservation, preserving about 97% of a food’s original nutritional value. It is considered more profitable nutrition-wise than buying imported fresh fruit from the store because freeze-dried foods are harvested in the time they are at the top of their ripeness level and packed with good nutrition. They are immediately frozen, which keeps in all the goodness of the fresh food!
- Removing moisture and water from food keeps it from spoiling and gives it a long-long shelf-life. Since freeze-dried food is not heated, it contains all the power of fresh food.
- Freeze-dried fresh fruit and berries possess superior quality due to extremely low temperatures and bypassing the liquid phase. Freeze-drying preserves the original color, taste, and nutritional value of the fresh product.
What exactly is freeze-drying?
Freeze-drying is a form of product preservation that removes all moisture and water, leaving the basic structure and content of the material intact. Freeze-drying, also known as lyophilization, is a low-temperature dehydration process that involves freezing the product, lowering the pressure, and removing the ice from the product through sublimation.
Freeze-drying is an amazingly effective method of food preservation, keeping all the nutrients, antioxidants, color, and taste of the ripe, in-season food. Freeze-drying can also separate and purify materials.
It sounds like freeze-drying is a relatively new process that has evolved with the development of technology. The first freeze-drying testing began as early as the 1890s when Richard Altmann successfully devised a method to freeze-dry tissues. He created a vacuum chamber run by an electrical pump. Still, it was not until World War II that the method was used both in medical and commercial food processing.
How freeze-drying food works?
Taking one of the most popular freeze-dried products, berries, as an example, let us see how the process unfolds step-by-step.
1. Picking the product. Imagine walking down an isolated forest road on a sunny day. A fresh pine scent fills your nose and birds sing the songs of ancient forest lore. With all this around you, you feel sheer happiness. That is why we always jokingly say that the forest berries are the most blessed berries – they are harvested by happy people in the fresh air with happy birds singing ‘Best of Happy Songs’ in the background. These ‘blessed’ berries are harvested from the beautiful organically certified Nordic forest at the exact right time when they have reached their full ripeness. That means if you choose Nordic wild blueberries, for example, you can enjoy getting the berries harvested in a small month-long window when they are most ripe and packed with antioxidants and nutrients. That means they contain as much goodness and nutrients as they ever would in the year-long period (you can read more about Nordic wild blueberries here).
2. Quality Control. Before the production process begins, the berries go through an in-depth cleaning process. In the case of organic products, they are also thoroughly analyzed to ensure that non-organic matter never reaches the final product. Not only are organic berries harvested from clean, certified forests, but they are restricted to a separate production line, apart from other non-organic products.
3. Freezing of the berries. The berries are transported to the freezer, where they are flash-frozen at an exceptionally low temperature. These temperatures are as low as -58 °F/-46 °C. Freezing berries right after they are harvested keeps a large portion of the nutrients from breaking down and, preserving the berries full of nutrients.
4. Freeze-Drying (aka Sublimation). The frozen berries are then placed under a vacuum, where the machine creates a powerful vacuum around the food, enabling the frozen solvent in the product to vaporize without passing the liquid phase. Then the sublimation process begins. It means the water in food is turned from solid directly to gas. The sublimation process begins when the molecules in food gain enough energy to break free from the molecules around it. The water turns from a solid state directly to a gaseous state, skipping a liquidus state, when the molecules have enough power to break free, but the surrounding conditions are not right for them to form a liquid state.
The water is removed from the food by vacuum. That process is the reason berries retain their original nutrition, good shape, color, and taste. All this process takes about 20-36 hours.
5. Secondary drying. This part of the process is also called desorption drying, which means berries are dried to the required final humidity. This takes place under reduced pressure with simultaneous heating. Removing moisture and water from food keeps it from spoiling and gives it an extra-long shelf-life. Removing the water makes the food a lot lighter as well. All that is left are the berries, preserving all the vitamins, minerals, antioxidants, and other nutrients as the fresh berries.
6. Packaging. When the product is dried sufficiently, it is sealed in a moisture-free package. When the package is secure, the product can have a years-long shelf-life.
Even after starting to use your goods, you should always seal the package as air-free as possible. Make sure to properly seal the package after each use to keep the powder from clumping and to preserve the quality of nutrients.
While the freeze-drying process may sound simple, it can be complex in practice due to the specific requirements for different raw materials.
The freeze-drying process allows the berries not only to keep their nutritional value but also gives them a longer shelf-life! Think about it: it’s the same healthy berry, but it lasts not only a couple of days but a couple of years (but of course this only happens when you forget the package to the pack of your cabinet or someone hides it for you – otherwise it would never happen, these berries are so good you will finish them by the end of the first week! 😉)
Why should you prefer freeze-dry food?
There are many benefits to choosing freeze-dried foods. Freeze-drying is a universal method of preservation. You can freeze-dry almost all kinds of foods, starting from fruit up until full plates of dinner meals.
Here are some benefits of choosing to freeze-dry preserved food:
- The original nutritional value of freeze-dried food is about 97%.
- If you are interested in an exotic or rare piece of food, then freeze-drying is your best option! The product is harvested at the peak of its ripeness and is flash-frozen right after, so they contain maximum nutrition. When fresh fruits are usually exported and transported, the time it takes for transportation is time spent on wasting vitamins and nutrients.
- Freeze-drying preserves a food’s original color, taste, appearance, and texture.
- Freeze-dried foods contain superior quality compared to other dehydrated methods.
- The product reconstitutes to its original state when placed in water.
- It will have a longer shelf-life.
- This food is lighter in weight, which why it is also preferred by hikers or mountaineers.
What is better: the freeze-dried or dehydrated approach?
Freeze-drying and dehydration are often compared. Dehydration and freeze-drying are both preservation methods that involve removing moisture. When freeze-drying involves removing the water and moisture by lowering pressure and then removing the ice by sublimation, then dehydration is a conventional method that evaporates water through heat.
Dehydration is an ancient method of preserving food. Dehydrating means removing moisture and water from food as much as possible. People have been doing this for a long time by leaving food in the sun to dry, to make it longer lasting.
Dehydrated food generally removes about 80-90% of its moisture, on the other hand, freeze-drying removes approximately 98-99%, giving it a longer shelf-life. Methods like canning and dehydration use high temperatures that destroy most of the food’s nutritional value. Also, freeze-drying gives food a long shelf-life of up to 20 years, whereas dehydrated, canned, or frozen food only lasts 2-4 years. To get the maximum amount of nutrients, the freeze-drying method is recommended.
Freeze-Drying vs. Dehydration
- Freeze-drying preserves more nutritional value. Heat-involved dehydration diminishes the nutritional value by 40-50%.
- The freeze-drying method keeps less moisture; therefore, the product has a longer shelf life.
- A larger variety of foods can be freeze-dried.
- The disadvantage of freeze-drying is the increased cost of the full process.