Morphology development during sessile single droplet drying of mixed maltodextrin and whey protein solutions

Abstract

A sessile single droplet drying method is employed to gain understanding on spray drying behaviour of mixed maltodextrin and whey protein solutions. Skin formation and subsequent locking of the skin and morphology development were the main aspects studied. Droplets of initial solids content of 30% (w/w), containing maltodextrin DE12 and whey protein in varying ratios were dried at temperatures ranging between 40 °C and 90 °C at a sessile droplet drying platform. The droplet composition did not influence the initial drying rate or locking point, but had major influence on the morphology of the final particle. Particles with high amount of whey protein and/or dried at low temperatures were smooth and spherical with one large vacuole, whereas high maltodextrin concentrations and/or high temperature particles gave a wrinkled surface and multiple vacuoles. Results suggest that composition and drying temperature have a strong influence on particle morphology, and can be altered to steer morphology. Skin formation being a determining factor in morphology development in whey protein-rich systems is explained by sol-gel transition and in maltodextrin-rich systems by reaching a viscosity value that leads to critical skin rigidity.