Sanxan–Whey Protein Isolate Composite-Fabricated Pickering HIPEs: Synergistic Stabilization, Environmental Tolerance and Enhanced Curcumin Bioaccessibility

Abstract

Traditional high internal phase emulsions (HIPEs) require high protein dosage and exhibit poor thermal-saline tolerance, limiting their application as clean-label food carriers for lipophilic nutrients. Sanxan (SAN) possesses unique gelling and emulsifying properties, while its application in HIPE systems remains largely unexplored. This study fabricated curcumin (Cur)-loaded HIPEs using SAN and whey protein isolate (WPI) at lower concentrations. A stable gel network formed at 0.8% SAN and 3% WPI. The oil-binding capacity reached 97.39%, remaining 96.74% and 97.03% after 0.1 M NaCl and 90 °C heating for 30 min. Cur encapsulation efficiency attained 83.23% at 3.5 mg/mL. FTIR verified non-covalent interactions, including hydrogen bonds, hydrophobic and electrostatic forces among SAN, WPI, and Cur. The SAN-WPI (SW)-HIPEs improved the antioxidant activity of Cur; compared with the WPI-HIPEs, ABTS and DPPH radical scavenging capacities increased by approximately 36.94% and 66.22%. In vitro digestion showed merely 1.06% Cur release in gastric fluid; the final intestinal release and bioavailability were 94.77% and 80.46%. This work clarifies the synergistic stabilization mechanism of SAN-WPI binary HIPEs and provides a low-protein formulation strategy to encapsulate and orally deliver lipophilic bioactives for functional food production.