Encapsulation and release of curcumin using an intact milk fat globule delivery system†
The stability and dispersibility of lipid-soluble bioactives in food systems are often modified via encapsulation in oil in water emulsions and lipid or protein-based nanoparticles. These encapsulation approaches frequently require the addition of surfactants/emulsifiers, sacrificial antioxidants, and high-energy methods to create the dispersed phase and stabilize encapsulated compounds. In contrast to conventional encapsulation approaches, this study evaluates pre-formed and naturally occurring lipid structures, milk fat globules (MFGs), for the encapsulation of a model lipid-soluble bioactive, curcumin. Intact MFGs were separated from raw milk and dispersed in water, and then curcumin was added in the presence of ethanol. Partitioning of curcumin to the lipid core of MFGs was confirmed using fluorescence imaging. The encapsulation efficiency and loading capacity of curcumin were measured. 1186.65 ± 14.63 μg of curcumin were encapsulated per gram of milk fat, in the presence of 10% v/v of ethanol with an encapsulation efficiency ranging between 59 and 64%. The study also evaluates the release of curcumin from MFG carriers under simulated gastrointestinal conditions, and correlates the release with morphological changes in milk fat globules during digestion. The results show limited release of encapsulated curcumin in the gastric phase (∼27%), and substantial release in the intestinal phase (>80%). Regarding their morphology, MFGs showed little changes in the gastric phase, and significant changes in the intestinal phase. Overall, the results of this study demonstrate encapsulation of a lipid-soluble bioactive compound in naturally occurring MFGs using a simple, rapid, and low-energy alternative to conventional encapsulation systems.