Surface formation phenomena of DHA-containing emulsion during convective droplet drying

Encapsulation of docosahexaenoic acid (DHA) protects this environment-sensitive substance from oxidation and also masks its odor. In this study, DHA was encapsulated with octenyl succinic anhydride modified (OSA) starch and whey protein concentrate. Single droplets of emulsions with different compositions were suspended on a glass filament to observe the dissolution behavior of dried and semi-dried particles. At each drying stage, the drying process were stopped to monitor changes in the semi-dried particle's morphology, either by attaching an additional water droplet or by keeping the semi-dried particle suspended in the drying chamber without air flow. Based on observations in the above-mentioned test, the crust formation phenomena of emulsion droplets with different compositions were compared at various drying stages. The microstructures of dried particles containing DHA were examined by scanning electron microscopy (SEM). The surface oil coverage and distribution were studied by observing the surface structure before and after oil extraction. The results obtained in this study indicate the underlying particle formation mechanisms during drying of DHA-containing emulsions formed with different wall materials.