Freeze dryer or lyophilizer is a dehydrator machine, it dry product and uses a technology called vacuum freeze drying: Works by freezing the materials, then reducing the drying chamber pressure, adding heat to materials and enable frozen water in materials to sublimate.
Tips: Freeze drying theory based on water triple point graph, that is: under water triple point pressure 610.5Pa, no liquid water exists, solid ice can sublimate directly to vapor if any heat energy provide.
Water Triple Point Chart
So, freeze drying actually is a low temperature drying method, and most of its processes are finished below zero degree. Which means it removes water from raw product but no ruin their texture, flavor and nutrition. In this regard, it is one of the best recommended drying methods, for any industry and application field.
Freeze Dryer Structure
Since the freeze drying process involves freezing, vacuum, heating and drying. So, a freeze dryer includes at least a drying chamber (where material placed), a vapor collector (temporary store the sublimated water), a vacuum system (create vacuum environment), a compressor system (chill the condenser) and a controller (control components working at automatic basis).
Freeze Dryer Structure
What’s the difference between freeze drying and lyophilization?
There is no difference, they are synonymous. Lyophilization is commonly used in the pharmaceutical and biological industries, while food manufacturers generally refer to Freeze Drying.
What are the steps of freeze drying? How to use a freeze dryer?
1, Freezing the product first
After product load on trays, put it in a low-temp freezer, until freeze solid.
2, Place it in vacuum chamber
Once the product is frozen, place it into drying chamber and create vacuum environment.
3, Add heat energy to frozen product
Under vacuum environment, proper add heat to frozen product, will encourage the solid ice sublimate to vapor and leave frozen product.
4, Collect the water vapor
The vapor leaves frozen product, has to go somewhere. Most freeze dryers inbuilt a vapor collect system called condenser, the condenser is ultra-low temperature (-25C or lower), it captures the vapor by simply condensing it and storing it as ice form. After freeze drying process finish, fill water into condenser, thaw and discharge it.
5, Harvest and packing
Once all ice in products has been sublimated and move to vapor collect condenser, the products are freeze dried and can be removed from lyophilizer.