In principle, an aqueous dispersion of oil in water emulsion containing carrier material dissolved in the water phase is converted into a dry powder by spraying the feed into hot dry air resulting in moisture evaporation.
It is used for drying liquid solutions and suspension with the objective producing light porous powder. Now, spray drying is a common practice in the food and dairy industries to make powders for capturing bioactive components and nutrients for a longer period of time.
Spray drying normally contains the following stages: atomization, air contact, evaporation, and product recovery.
Finely divided drops of liquid food are dried by direct contact with heated air in extremely short residence time of 3 – 30s, which results minimum heat degradation of dried product.
Liquid is transferred to fine drop by using their:
*Rotary
*Pressure nozzle
*Pneumatic two fluid atomizing device
Spray drying is the accepted method for the production of milk and whey powders, coffee creamers, cheese powder, dehydrated yeast extract, instant coffee and tea, isolated soybean protein, enzymes, maltodextrin, egg powder and many other products in powder forms.
Process of spray drying