Food Freeze Dryers
Food freeze dryer is a machine that stores and preserves high-quality food by dehydrating food content. The machine operates at low temperature and high pressure. It uses a process known as the lyophilization. Through this process, it lowers the temperature of food to be preserved.
The freeze drying process was first applied to food products after the Second World War, in order to preserve and store foods without the need for refrigeration. Coffee was one of the first freeze dried food products to be produced, but now vegetables, fruits, meats, fish, dairy products, herbs and food flavourings can be successfully freeze dried.
The primary purpose of freeze drying within the food industry is to extend the shelf-life of the food while maintaining the quality.Freeze-drying is known to result in the highest quality of foods amongst all drying techniques because structural integrity is maintained along with preservation of flavors.Because freeze drying is expensive, it is used mainly with high-value products. Examples of high-value freeze-dried products are seasonal fruits and vegetables because of their limited availability, coffee, and foods used for military rations, astronauts/cosmonauts, and/or hiker.
The Food freeze-drying process
Freeze-drying, or lyophilization, removes moisture from raw, frozen product through a vacuum system and process called sublimation.
Frozen raw product is cut down to the desired piece size and spread evenly onto trays that are stacked and stored in freezers. The sized product freezes at an even colder temperature, reaching an optimal state at which the original shape of the product can be retained.
The trays are then loaded into a refrigerated freeze-drying chamber that seals tightly shut. The chamber’s vacuum system removes ice from the product and converts it directly to a vapor without moving through the liquid state, in a process called sublimation. Since the water is removed from the product in a frozen state, cell structure remains intact and finished product bears close resemblance to its fresh counterpart, thus retaining its piece identity.
Advantages of freeze-drying
1. Whole food nutrition
Shifting consumer values have led more people to seek nutrition from real, high-quality food sources with understandable labels. Because they are minimally processed, freeze-dried foods can be clean ingredients, free from synthetic, artificial, and highly processed materials.
Freeze-dried fruits and vegetables are also real fruits and vegetables, giving brands the ability to make claims based on nutritional value. Van Drunen Farms’ TruServ™ program provides an exclusive method of substantiation that connects our production data and the USDA nutrient database to only our fruit, vegetable and leafy green ingredients.
Consumers’ desire for nutrition from real and understandable sources drives the appeal of verified, whole food serving claims from freeze-dried fruits and vegetables. Reach on-the-go millennial consumers with whole food servings in convenient delivery forms like bars or bites.
2. Closest to the fresh form
Freeze-drying retains nutritional value better than other drying methods, further supporting consumers’ desire for nutrition from whole foods. The process also preserves the actual color and shape of the original raw material, reassuring consumers they are actually getting real fruits and vegetables in their diets. The intense flavor and aroma of freeze-dried ingredients also closely resembles the profile of the raw material.
Another advantage of freeze-drying is the ability to customize to unique needs and project goals. Freeze-dried ingredients can be cut or ground into many different sizes and shapes – everything from whole fruits and vegetables down to fine powders. Finished product can be easily mixed into any blend or formulation for a flavor profile completely unique to your final product.
4. Application variety
Customization and blending capabilities give food processors the ability to incorporate real fruits and vegetables into a large variety of applications. Growing categories of freeze-dried applications include breakfast applications like hot and cold cereals, retail-ready or ready-to-eat snacks, and beverage applications like smoothies or whole fruit pieces added to beverages.
5. Prolonged shelf life
The shelf life of any given product directly links to the moisture content of that product. Removing water through the freeze-drying process removes potential for bacterial growth. Moisture content varies from product to product, but an average for freeze-dried products is around 3% moisture. Actual length of shelf life for any given freeze-dried product depends on packaging, storage temperature and the product itself.
Food Types Suitable For Freeze Drying
NASA and military rations
Because of its light weight per volume of reconstituted food, freeze-dried products are popular and convenient for hikers, as military rations, or astronaut meals. A greater amount of dried food can be carried compared to the same weight of wet food. In replacement of wet food, freeze dried food can be easily be rehydrated with water if desired and shelf-life of the dried product is longer than fresh/wet product making it ideal for long trips taken by hikers, military personnel, or astronauts. The development of freeze drying increased meal and snack variety to include items like shrimp cocktail, chicken and vegetables, butterscotch pudding, and apple sauce.
Coffee contains flavor and aroma qualities that are created due to the Maillard reaction during roasting and can be preserved with freeze-drying.Compared to other drying methods like room temperature drying, hot-air drying, and solar drying, Robusta coffee beans that were freeze-dried contained higher amounts of essential amino acids like leucine, lysine, and phenylalanine. Also, few non-essential amino acids that significantly contributed to taste were preserved.
With conventional dehydration, berries can degrade in quality as their structure is very delicate and contains high levels of moisture. Strawberries were found to have the highest quality when freeze dried; retaining color, flavour, and ability to be re-hydrated
Some foods freeze dry very well, but not all food is suitable for freeze drying. Small fruits and vegetables can be easily freeze dried, whereas whole fruits and large vegetables would not be suitable, although they can be freeze dried if cut into small pieces first. This also applies to meat; small chunks of meat freeze dries well, but larger fillets need to be cut into pieces. Meat and seafood also require cooking before freeze drying. For some foods freeze drying is not cost-effective.
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