Physicochemical characterization and stability of microbeads containing cod-liver oil encircled with natural cyclodextrins

The ability of cyclodextrins (CDs) to solubilize cod-liver oil in aqueous solutions was evaluated. Only the natural α-cyclodextrin (αCD) and γ-cyclodextrin (γCD) were able to fully disperse 10 % (v/v) cod-liver oil in aqueous solutions. Confocal imaging revealed that the oil was located in the center of the CD enveloped microbeads (<20 μm in diameter) where it was enclosed within nanocompartments (<1 μm in diameter). The aqueous microbead suspensions were lyophilized to produce dry powder microbeads with rough surfaces. To assess the stability of the cod-liver oil/γCD (3:1 molar ratio) microbead powder, three groups of samples were incubated over a period of 1, 2, 4, 12 and 84 weeks. Group 1 (G1) and group 2 (G2) were incubated at 25 °C and 60 % humidity. G1 was exposed to O₂ for 10 min before sealing off the glass containers while G2 was kept under nitrogen. Group 3 was stored under accelerated conditions at 40 °C and 75 % humidity under nitrogen. The reference was pure cod-liver oil. Results indicated that encapsulating cod-liver oil with γCD delays oxidative degradation when oxygen is present, but does not significantly decrease or increase the long term stability of cod-liver oil under anaerobic conditions. Cod-liver oil/γCD microbeads could be compressed into tablets without decreasing the integrity of encapsulation. The cod-liver oil/γCD microbead powder might be of interest to the pharmaceutical industry as a carrier for lipophilic drugs.