Preparing O/W/O Emulsion for Curcumin (Curcuma longa) Delivery and In Vitro Digestibility Assay

In this study, simple oil-in-water emulsions (O/W) and multiple O/W/O emulsions were employed as carriers for a curcumin delivery system. The stability of emulsions was evaluated using DSC (differential scanning calorimetry), accompanied by particle size measurement by DLS (dynamic light scattering) and rheological analysis. The amount of freezable water (W_fs) in O/W emulsion was determined to be 80.4%, while that in O/W/O emulsion was 23.7%. Multiple emulsions had a more complex structure than simple emulsions, being characterized by higher stability with predominant loss modulus over storage modulus (G" > G'). The mean surface diameter for O/W emulsion was 198.7 ± 9.8 nm, being approximately two times lower than that for multiple emulsions. Curcumin in vitro digestibility was observed for both emulsions and, additionally, the digestibility of fresh and dried curcuma root powders was investigated. Multiple emulsions were found to be a superior matrix for curcumin delivery, with higher stability and emulsion digestibility of 50.6% for the stomach and small intestine. In vitro digestion of dried curcuma powders and curcuma root samples was monitored by HPLC (high-performance liquid chromatography). The DMD (dry matter digestibility) for dried curcuma powders ranged between 52.9% to 78.8%, and for fresh curcuma (KF) was 95.5%.