Spray drying behaviour and functionality of beta-lactoglobulin-/pectin-stabilized oil-in-water emulsions

Aim of the present study was to investigate the impact of atomization and drying on the functionality of emulsions with an oil/water-interface (o/w-interface) consisting of beta-lactoglobulin (single layer emulsion) and sequentially adsorbed pectins with varying degree of methylation at pH<pI (bilayer emulsions). Thus, the emulsion systems were characterized with respect to their behavior during atomization, their drying behavior in single droplet experiments and the oxidative stability of the dispersed phase (fish oil) during storage of liquid and spray-dried single and bilayer emulsions. The o/w-interface of the emulsions was predominantly elastic, although the elasticity was higher in single layer emulsions compared to bilayer emulsions. The drying behavior of the different emulsions during levitation of single droplets was similar. Regarding the atomization process, the emulsion spray droplet size generally decreased with increasing energy input irrespective of the type of atomizer. With rotary atomization, the spray droplet size distribution of the different emulsions was similar. The oxidative stability of the oil was influenced by both the physical state of the emulsions and the different constituents at the o/w-interface. In the liquid state, the oxidative stability was higher in the original emulsions when compared to the reconstituted emulsions. The differences in oxidative stability in the spray-dried emulsions can partly be attributed to the microencapsulation efficiency, but also the physical characteristics of the o/w-interface, which needs to be investigated in more detail.