Surface composition analysis of nano-particle encapsulated powders

In this work, nano-particle encapsulation by spray drying was undertaken by preparing sub-micron emulsions via high energy emulsifying techniques, namely Microfluidization and ultrasonication. The attention was given to the surface oil content and surface oil coverage of encapsulated powders which are very significant parameters in the encapsulation process. The surfaceoil content and composition of the fish oil encapsulated powders was analyzed by extraction and X-ray photoelectron spectroscopy (XPS), respectively. Our results revealed that Microfluidization was an efficient emulsification techniqueresulting in h the lowest unencapsulated oil at the surface of particles, mainly due to its capability to produce emulsions at the nano-range (d43 of 210-280 nm). XPS analysis showed that different biopolymers (Hi-Cap and WPC) resulted in almostsimilar encapsulated powders in terms of surface oil coverage, and emulsion size was significantly affecting the final results. In fact, there was a strong correlation between emulsion droplet size and surface oil coverage of encapsulated powders. The results were confirmed with scanning electron microscopy (SEM) analysis of encapsulated powders.

Keywords:

Surface oil content , Nano-emulsion , Emulsification , Surface oil coverage , Microfluidization