Role of powder particle size on the encapsulation efficiency of oils during spray drying

In this study, emulsions prepared by microfluidizer and ultrasound were spray-dried to produce encapsulated powders containing d-limonene or fish oil (20% w/w). Maltodextrin combined with a surface-active biopolymer (modified starch or whey protein concentrate) was used as the wall material (40% solids w/w). It was shown that volatility of the core material significantly affects the surface oil content of the encapsulated powder. Also, by the classification of encapsulated powders into various sizes, our results revealed that larger particles (> 63 mu m) retain more volatiles than smaller ones (< 38 mu m), but at the same time there is more unencapsulated oil at the surface of big particles. In the case of fish oil, although surface oil content obtained by solvent extraction was high in larger particles, X-ray photoelectron spectroscopy analysis showed that different particles had similar surface oil coverage.