Encapsulation of Curcumin in Casein-Dextran Sulfate Nanocomplexes to Improve Acid Stability and Bioaccessibility

Lipophilic phytochemicals such as curcumin have attracted considerable interest due to their potential health benefits. Curcumin has poor water-solubility and poor bioavailability due to its crystallinity. Although numerous protein-based colloidal delivery systems have been studied to enhance these functional properties of curcumin, few systems are dispersible at acidic conditions of most beverage products. The objective of this thesis was to study the properties of nanocomplexes formed with sodium caseinate (NaCas) and dextran sulfate in encapsulating curcumin for acid stability and bioaccessibility. For encapsulation, curcumin was dissolved at 3 mg/mL in dispersions with 0.5 % w/v NaCas and 0.5 % w/v DS at pH 13.0, followed by adjusting pH to 7.0, 4.6, and 3.0. The supernatants after centrifugation were either freeze-dried or directly characterized. The encapsulation efficiency at pH 7.0, 4.6, and 3.0was 94.8%, 90.2%, and 77.3%, respectively, while the respective loading capacity was 22.3%, 21.5%, and 19.9%. The encapsulation efficiency remained similar (P > 0.05) after 31-day ambient storage except for the significant reduction at pH 3.0 on day 31 (P < 0.05) due to slight precipitation. Bigger Z-average diameters (