In vitro bioaccessibility of fish oil-loaded hollow solid lipid micro- and nanoparticles

Fish oil-loaded hollow solid lipid micro- and nanoparticles were prepared by atomization of the CO2-expanded lipid mixture. The obtained particles were spherical and free-flowing with an average particle size of 6.9 μm. Fish oil loading efficiency was achieved at 92.3% (w/w). The in vitro digestive stability, lipid digestibility and EPA and DHA bioaccessibility of the fish oil-loaded particles were examined using an in vitro sequential digestion model. The mean particle diameter increased markedly after oral (15.2 μm) and gastric (32.4 μm) digestion and then decreased after the small intestinal stage (24.0 μm). Fish oil-loaded particles remained spherical and intact but mainly agglomerated on the top phase throughout the oral and gastric digestion. However, a mixed digesta was formed after the small intestinal digestion, which contained digested broken particle pieces, undigested fish oil-loaded particles, free fatty acids, monoacylglycerols and micelles. The extent of lipolysis was significantly increased for the 30% fish oil-loaded particles as compared to physical mixtures of empty hollow solid lipid particles or bulk FHSO and fish oil (p < 0.05). Moreover, EPA and DHA bioaccessibility was significantly improved from 9.7 to 18.2% with the 30% fish oil-loaded particles (p < 0.05).