Comparing the evaporation kinetics and dried morphologies of particles generated by spray dryers and single-particle techniques

Understanding the fundamental processes that govern the morphology development of particles in spray dryers is crucial for optimising product quality and process efficiency. Previous attempts at utilising single droplet drying (SDD) studies to recreate spray dried powder morphologies have failed to account for the large temperature gradients present in an industrial drying chamber. Furthermore, only simple dairy-based solutions have been investigated. Here we present a novel method for reproducing the morphologies of a bench-top spray dryer using an SDD approach, by parameterising the drying regime of droplets in a spray dryer and recreating limits of that drying regime in a falling droplet column (FDC). A matrix of complex, fat free, dairy-based solutions were produced to observe the effect of carbohydrate content, protein type and fibre content on the drying behaviour and morphology of the resultant particles. It was observed that the casein content had the largest affect on both droplet evaporation rate and particle morphology, making the particles more buckled. Fibre content had no effect on the particle morphology.