Spray drying of dairy products: state of the art

Milk is extremely perishable, and yet, for a number of reasons, it has to be preserved for later consumption. The removal of water prevents the growth of micro-organisms and facilitates preservation and storage of milk constituents. Spray drying is one of the most convenient techniques for producing milk powders and for stabilizing milk constituents. Before spray drying, the milk undergoes several processes (such as heat treatment, cream separation, membrane processes, vacuum evaporation and homogenization). The chemical, physical, technological, nutritional, functional and microbiological properties of final products are influenced by a number of factors such as operating conditions, properties of the dairy products and storage conditions. The aim of this review is to describe the process of spray drying of dairy products and to review the present and recent advancements of knowledge on the properties of spray-dried milk products, on modelling and water transfer simulation (drying and rehydration), dairy powders and the spray drying equipment and energy consumption.