SIMULATION OF WATER TRANSFER IN SPRAY DRYING

A drying method by desorption in a water activity meter (Aw-meter) was used to simulate the conditions of spray drying and to determine the water transfer inside the dairy concentrate to the surface (first transfer) and from the surface to the drying air (second transfer). A limitation in the first transfer decreased the second transfer. The percentage of bound or unbound water was determined as a function of the nature of concentrates (milk concentrate, high protein milk concentrate, native casein suspension, caseinate dispersion, ) before drying. The water transfer in the different dairy concentrates during drying was shown as a function of the environment of their water content and the nature of the constituents. The percentage of bound or unbound water and the drying behavior of any dairy concentrate could be determined in 4 to 6 hours and might predict spray drying behavior in an industrial tower.