On the other hand, freeze drying is a more complex process. One that involves 3 main steps:
Removing the moisture through sublimation
The end product is completely different than “dehydrated” foods. Because of this complexity, it takes dedicated, high-tech equipment to freeze dry food.
Like dehydrating, you place food on large open racks to allow for air circulation. But, instead of placing the food in a high temp environment, you load the racks into a vacuum chamber.
Then the freeze dryer lowers the temperature inside the vacuum chamber. To an incredible low temp (around -40deg F).
Once the food is completely frozen, a vacuum pump lowers the pressure inside the chamber. And then the temperature is slowly raised back to normal.
Due to the reduced pressure, the water in the food “sublimes”.
Sublimation is the process where solid ice changes directly into water vapor without ever becoming liquid.
The food gives up its water content without sacrificing texture, flavor, or nutrition.
So, if it’s more complex to freeze dry foods, why choose it over dehydrating?
More Moisture Removal
One of the main reasons to remove moisture from food is to prevent the spread of mold and bacteria.
All living organisms need moisture to thrive. So by lowering the water contents, it’s nearly impossible for them to survive.
Most home dehydrators can remove about 90 to 95 percent of the water contained in foods.
By comparison, freeze drying will remove up to 98 to 99 percent of moisture content.
The bottom line:
Freeze drying food removes more moisture. Thus it has a much better shelf life than dehydrated foods.
GuanFeng is your specialist in drying techniques and all your partner for Freeze Dry Machine . The great variety of drying processes enables Guanfeng to always give good and honest customized advice and help you decide which machine best matches your requirements.Please contact us or check below link: https://www.gf-machine.com/ if you have any question.