Nanoemulsion- and emulsion-based delivery systems for curcumin: Encapsulation and release properties

Curcumin has been reported to have many biological activities, but its application as a functional ingredient is currently limited because of its poor water-solubility and bioaccessibility. This study investigated the impact of different lipid-based formulations on curcumin encapsulation and bioaccessibility. Oil-in-water nanoemulsions (r < 100 nm), or conventional emulsions (r > 100 nm), were prepared with different lipids: long, medium, and short chain triacylglycerols (LCT, MCT and SCT, respectively). An in vitro model simulating small intestine digestion conditions characterised rate and extent of lipid phase digestion. A centrifugation method determined fraction of curcumin released into mixed micelles after digestion (bioaccessibility). Initial digestion rate decreased in the order SCT > MCT > LCT, while final digestion extent decreased in the order MCT > SCT > LCT. The bioaccessibility of curcumin decreased in the order MCT > LCT ≫ SCT and appeared to be slightly higher in conventional emulsions than in nanoemulsions.