Characterization of spray-dried layer-by-layer emulsions

Aim of the present study was to characterize the process of atomization and drying of layer-by-layer emulsions containing lecithin (single layer emulsion) and lecithin/chitosan (multilayer emulsion) and the oxidative stability of the spray-dried emulsions during storage. For this purpose, the analysis of the emulsion spray droplet size during atomization by two different atomization devices, i.e. two-fluid nozzle and rotary atomizer, was carried out to identify suitable process parameters. The drying behaviour of single layer and multilayer emulsions was investigated by single-drop drying via calculation of the mass transfer during acoustic levitation. In spray-dried emulsions, the oxidative stability in the single layer emulsions was higher than in the multilayer emulsion. This was partly attributed to a lower microencapsulation efficiency in the spray-dried multilayer emulsion compared to the spray-dried single layer emulsion. Furthermore, it could be shown, that excess chitosan in the bulk carrier matrix affects the free volume elements and thus oxygen diffusion.