Define the Spray Drying Method?

Spray drying is a unique drying process since it involves both particle formation and drying. It is most suitable for drying of liquid foods such as milk, fruit juices etc. The feed is converted into small droplet with the help of a nozzle or atomizer and then droplets are dried in a drying chamber when they come in contact with hot air. The product is separated from hot air by a cyclone separator and collected. The characteristics of the resultant powder can be controlled and powder properties can be maintained constant throughout a continuous operation. With the designs of spray dryers available, it is possible to select a dryer layout to produce either fine- or coarse-particle powders, agglomerates or granulates. Spray drying involves the atomisation of feed into a spray, and contact between spray and drying medium resulting in moisture evaporation. The drying of the spray continues until the desired moisture content in the dried particles is achieved, and the product is recovered from the air. There are various types of spray dryers such as two stage dryers, three stage dryers, multi stage dryers and compact spray dryers.