Informative — Medicine
History of Freeze Drying 0
Freeze-drying, or lyophilization, is the removal of water from frozen food through a process called sublimation.1 This process is done under a vacuum and low temperatures, and the product freezing solidly during the process.2Freeze drying removes water from the food to make it last longer. The water's vaporized through the process of sublimation, where water, in solid state, changes directly to vapor, producing a product with controllable moisture.2 It's a perfect way to preserve food, since freeze dried food products don't shrink.3 Freeze dried foods can be stored without cooking or refrigeration. They need no additional flavor or color modification. Freeze dried foods are also light and are ideal for space travel, camping, backpacking, and traveling.1
The Process
Freezing - the product frozen to enable low-temperature drying.
Vacuum - placed under vacuum to allow the frozen solvent to vaporize through sublimation: it doesn’t pass through the liquid phase.
Heat - applied to the frozen product to accelerate sublimation.
Condensation - low temperature enforced by the condenser plates to remove the vaporized solvent from the vacuum chamber by converting it back to a solid. This completes the process of separation. The result is a dry product.2
The History of Freeze Drying
Freeze drying origins are traced back to the ancient Peruvian Incas of the Andes in the 15th century. 2 1 They stored their crops, like potatoes, on the mountain heights above Machu Picchu. The cold mountain temperatures froze the food stores, and water gradually vaporized under low pressure because of the high mountain altitudes - freeze drying the food.3 Buddhist monks living on the sacred mountain "Koya" used this technique. They stored tofu in the mountain snow, where the high altitudes and cold winds freeze dried the tofu. 3
In 1905, Benedict and Manning created the first freeze dryer, which dried the blood tissues using a chemical pump.3 In 1910, Shackell modified the basic design of the Benedict and Manning pump to an electrically driven pump to create the required vacuum, instead of the displacement of air with ethyl ether used in the original design.2 In 1934, the US patent was issued to Elser for creating the drying equipment that replaced Shackell’s design with a cold trap chilled with dry ice.3
Modern Freeze Drying
In the 1940s during World War 2, freeze drying took on the modern method, due to the need for blood.3 The blood sent to Europe from the US for the medical treatment of wounded soldiers required refrigeration.4 Due to the lack of refrigeration and transport, blood supplies would spoil before arriving at their destination;1 So, more modern freeze drying techniques had to be created to preserve blood plasma, making it possible for the blood to be chemically stable without the need for refrigeration. 2
The medical community implemented freeze drying for penicillin and bone.4 They recognized freeze drying as an important technique for preservation of biological matter.1 A freeze dryer was used, and it had a large chamber for freezing and a vacuum pump for removing moisture.2 From then on, freeze drying became a preservation technique for pharmaceuticals and food.1 Since the 1960s, over 400 different types of freeze dried foods have been produced commercially using freeze drying.2 NASA adopted this technique in 1968, and created freeze dried ice cream.
Freeze dried coffee outruns all other freeze dried products in popularity. 2 First produced in 1938 by Nestle after Brazil requested the company to help them find a solution to the coffee surplus, Nescafe, an instant coffee powder, debuted in Switzerland. It paved the way to the production of powdered food products.2
Freeze drying evolves continually. More products pop up more every year, because freeze drying's popularity has grown for a variety of different foods and flavors. They retain their natural composition, and the integrity of minerals, vitamins and other nutrients.
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