Fabrication and Characterization of High Internal Phase Pickering Emulsion Gels Stabilized by Hesperidin and Lysozyme.

The development of novel multifunctional emulsifiers using protein-polyphenol interactions is a common strategy. Previously, we investigated the emulsifying properties of the four citrus flavonoids alone. This study investigated how complexing lysozyme (LY) with four citrus-derived flavonoids affects emulsifying properties. Results demonstrated that the emulsification performance was enhanced when flavonoids were complexed with LY, following the order: hesperidin (Hpd) > neohesperidin dihydrochalcone (Neohpddic) > neohesperidin (Neohpd) > hesperetin (Hpt). This enhancement was positively correlated with the intrinsic emulsification abilities of the flavonoids, suggesting that the synergistic effect should not overlook the emulsifying capacity of the flavonoids themselves. The Hpd-LY mixture increased the three-phase contact angle (to near 90°) compared to Hpd alone (51.16° ± 0.58), which helped form high internal phase emulsion (HIPE) gels. Stable HIPEs were achieved at an oil phase fraction φ = 80%, mixture concentration w ≥ 0.8%, and Hpd-to-LY ratio k ≥ 1:1. Droplet size decreased as w increased from 0.6% to 1.2%, but increased with higher φ and k, while gel strength improved. In addition, these HIPEs protected encapsulated lutein and suppressed lipid oxidation. The findings show that flavonoid-protein complexes, especially Hpd-LY, can build stable and functional HIPEs for protecting bioactive compounds.