Encapsulation of fish oil into hollow solid lipid micro- and nanoparticles using carbon dioxide

• Fish oil-loaded powder hollow solid lipid micro- and nanospheres were formed.
• The highest loading efficiency of 97.5% was at 50% initial fish oil concentration.
• Polymorphic form transformed from α to β and β′ when loaded with fish oil.
• Oxidative stability of fish oil in solid lipid micro- and nanospheres increased.

Fish oil was encapsulated in hollow solid lipid micro- and nanoparticles formed from fully hydrogenated soybean oil (FHSO) using a novel green method based on atomization of supercritical carbon dioxide (SC-CO2)-expanded lipid. The highest fish oil loading efficiency (97.5%, w/w) was achieved at 50%, w/w, initial fish oil concentration. All particles were spherical and in the dry free-flowing form; however, less smooth surface with wrinkles was observed when the initial fish oil concentration was increased up to 50%. With increasing initial fish oil concentration, melting point of the fish oil-loaded particles shifted to lower onset melting temperatures, and major polymorphic form transformed from α to β and/or β′. Oxidative stability of the loaded fish oil was significantly increased compared to the free fish oil (p < 0.05). This innovative method forms free-flowing powder products that are easy-to-use solid fish oil formulation, which makes the handling and storage feasible and convenient.