The influence of emulsion drying on the fatty acid composition, bioactive compounds content and oxidative stability of encapsulated bio-oils

The study investigated the influence of spray- and freeze-drying on the bio-oil powder quality. The powders were characterized by process efficiency, structure, colour, oil and bioactive compounds contents, fatty acid composition and oxidative stability. Cold-pressed bio-oils of evening primrose, borage and blueweed were homogenized with wall materials and water followed by spray-drying at 130°C inlet air temperature or freeze-drying at −56°C. It was shown that lower encapsulation efficiency of freeze-drying process correlated with higher surface oil content. The content of bioactive compounds was more affected by the processes than the fatty acid composition regardless of the method of drying. The powders produced by freeze-drying had a higher tocopherol content than those produced by spray-drying. Both spray- and freeze-drying significantly contributed to the changes of sterols concentration, but the changes were greater for bio-oil powders obtained by spray-drying.