Drying operations involve the removal of all moisture to the required level. Surface moisture (and it is often assumed that it is only type of moisture present) is conventionally removed by raising the product temperature by using hot air to vaporize the moisture. However this can result in product spoilage as many products like cocoa, gelatin, coffee etc are temperature sensitive and need to be dried at low temperature.

Drying operations involve the removal of all moisture to the required level. Surface moisture (and it is often assumed that it is only type of moisture present) is conventionally removed by raising the product temperature by using hot air to vaporize the moisture. However this can result in product spoilage as many products like cocoa, gelatin, coffee etc are temperature sensitive and need to be dried at low temperature.