In situ nanoencapsulation of curcumin in egg yolk low-density lipoprotein gels: Calcium-regulated protein network restructuring and stability enhancement.

The structural compactness of egg yolk low-density lipoprotein (LDL) limits its application in protein-based hydrogels for hydrophobic bioactive delivery. In this study, calcium ion-regulated gelation was employed to induce LDL network restructuring and enable in situ nanoencapsulation of curcumin. Ca2+ promoted LDL aggregation and gel network formation through electrostatic screening and charge bridging, accompanied by increased β-sheet content and enhanced hydrophobic interactions. As a result, a hierarchically interconnected protein network with hydrophobic microdomains and nanoscale confinement spaces was generated, allowing synchronous incorporation of curcumin during gel formation rather than post-gelation entrapment. Consequently, curcumin encapsulation efficiency increased from 63.3% to 93.2%, with markedly improved photothermal stability and digestion-responsive release behavior. The resulting gels exhibited elastic-dominant viscoelasticity and pronounced shear-thinning behavior. This study elucidates an ion-regulated lipoprotein gelation mechanism and provides a structurally tunable platform for functional bioactive encapsulation in food systems.