Pickering emulsion hydrogel beads for curcumin encapsulation and food application

Curcumin is a bioactive supplement known to have many medical benefits. However, it has low bioavailability due to its insolubility and rapid degradation in aqueous solution. In this paper, sodium alginate beads and cellulose nanocrystal-stabilized Pickering emulsion (CNCPE) were employed to improve the bioavailability of curcumin. In brief, curcumin was first encapsulated in the CNCPE, and then immobilized in an alginate hydrogel matrix, to yield CNCPE-Alg beads. Curcumin was successfully encapsulated in the oil droplets of the beads with near 100% encapsulation efficiency. Besides, the improved storage stability of curcumin was achieved, with a half-life of 160 days. As part of the study, the curcumin-containing beads were incorporated into common food systems (i.e., milk, apple juice, yogurt, and mineral water). The beads demonstrated high physical stability, even after 28 days of storage in food systems. Notably, about 30% of curcumin leaked from the beads into the milk and yogurt systems due to the presence of the inherent fat contents in both systems. The release profile of curcumin was investigated using mathematical models, indicating a diffusion-driven release. In vitro experiments showed that curcumin was completely released from CNCPE-Alg beads during intestinal digestion. Our findings indicated the great potential of CNCPE-Alg beads as a food-compatible encapsulation system for sensitive lipophilic bioactive compounds.