Structural Modification of O/W Bigels by Glycerol Monostearate for Improved Co-Delivery of Curcumin and Epigallocatechin Gallate

Bigels of oleogel-in-hydrogel structures were developed as carriers for curcumin and epigallocatechin gallate (EGCG), and the roles of oleogelator (glycerol monostearate, GMS) content on the structures and delivery functionality were elucidated. The results indicated that hardness and viscosity of the bigels were gradually enhanced with the increase in GMS content. In the meantime, oil holding capacity of the bigels was improved, while water holding capacity remained unchanged. XRD analysis and CLSM observation revealed that higher GMS content contributed to higher crystallinity and more compact gel systems. When curcumin and EGCG were incorporated within bigels, their release could also be modulated by the gel structures. Curcumin was slowly released in gastric digestion and rapidly released in intestinal juices. Higher content of GMS led to a much lower release rate of curcumin. EGCG was quickly released in the gastric juice, and the release rate was almost constant afterward. GMS content had little effect on the release of EGCG. The information obtained proved that bigels could codeliver functional ingredients of different polarities, whose release could be modulated by gel structures.