ABSTRACT Spray drying of emulsions is a commonly used technique in the food industry for the encapsulation of oil in food powders, yet oil droplet redistribution to the surface of a drying emulsion droplet can negatively affect powder flowability. While previous studies have investigated either the influence of process and formulation parameters or certain powder structure parameters such as encapsulation efficiency and residual moisture on flowability, this work aims to deepen the understanding of the mechanistical link between the flowability (‐value determined using a ring shear cell) and relevant structural parameters. For this, residual moisture, water activity, encapsulation efficiency and extractable surface oil were chosen and compared in their ability to correlate with powder flowability. Crucially, water activity and extractable surface oil were identified as significantly stronger predictors of flowability compared with traditional metrics such as residual moisture. A reduction in the oil content and a lower drying outlet temperature led to improved flowability, which could be linked to changes in the extractable surface oil content and water activity of spray dried particles. By highlighting these water activity and free surface oil as the primary drivers of powder flowability, this work allows for a more optimized spray drying process design.
Höhne et al. (Tue,) studied this question.