The role of viscosity in morphology development during single droplet drying

Abstract Particle morphology influences the final quality of a powdered product. However, the mechanisms behind morphology formation are not completely understood yet. In this study particle morphology is linked to rheological properties of the concentrated liquid formulations at high concentration. Shear rate sweeps showed jamming of the whey protein at concentrations of ~50% (w/w), whereas maltodextrin remained liquid-like up to concentrations of ~70% (w/w). Morphology development of the latter components during single droplet drying showed that it could be influenced by altering initial droplet size and dry matter content. If droplets had a high initial dry matter (50% (w/w) morphology development started immediately, and the formed morphology could be explained by the rheological behavior of the mixture at that concentration. This indicated that measuring the rheological properties at high concentrations can provide insight in morphology development. Gaining insight on morphology development will eventually lead to higher quality powdered products.