Improving the physical and wettability properties of skim milk powders through agglomeration and lecithination

Abstract

This study aimed to reduce the bulk density of skim milk powders (SMP) and improve subsequent wettability and dissolution by a combination of agglomeration and lecithination. Agglomeration significantly increased powder particle size from a D90 of 120–201 μm, and decreased tapped bulk density (0.73–0.65 g/cm3), although it led to increased friability (32.7%) compared to regular SMP (22.9%). Spraying lecithin on to SMP in the fluid bed improved wettability (8.94 s) compared to regular SMP (>300 s). Agglomeration without lecithination had no effect on powder wettability, similarly, adding lecithin in to liquid skim milk concentrate prior to drying did not improve subsequent powder wettability. Overall, improving the functionality of skim milk is quite complex, and while powder bulk density can be reduced by agglomeration, the particles remain susceptible to breakdown, and the wettability is relatively poor, although this can be improved by spraying lecithin directly on to the powder particles.