Lyophilization? What is that? It’s not surprising if you haven’t heard the term, but lyophilization (lī-ˌä-fə-lə-ˈzā-shən) is the proper name for freeze-drying. Freeze-drying is both art and science, ultimately leading to a product that can serve many uses (and not just in the food industry). The process can be broken down into three components, which when performed together, result in perfectly freeze-dried food.
Freezing the product
Freeze-drying relies on a process called sublimation. Predictably, the phase change from solid to gas requires that you begin with a solid. Many fruits and vegetables, for example, have a lot of liquid inside of them that must be frozen first. Usually, the freezing is done on trays or in vials at atmospheric pressure. You don’t want to freeze too much or too little, as that can adversely affect the final product.
Next, we move to the vacuum chamber.
In order for sublimation to take place, the pressure and temperature must be exactly right for the ice to turn to vapor. First, pressure: The atmospheric pressure within the freeze-drying chamber must be low enough to force the phase change from solid to gas. If the pressure isn’t low enough, the ice will simply melt, resulting in liquid and mushy fruit.
The heat is on
Once the pressure has been lowered enough, subtle levels of heat are applied to trigger sublimation. The frozen liquid in whatever product is being preserved is forced out as a gas, which then travels to a different part of the machine and is frozen again, or collected separately from the food being freeze-dried. This can take hours, or sometimes days. Once it’s complete, however, you have freeze-dried food ready for packaging.
We take pride in our custom-built freeze-dryers, and our process ensures speed and quality no matter the product. If you are curious about freeze-drying and would like to learn more, contact us or get in touch on Twitter or Facebook.