Sodium caseinate/pectin complex-stabilized emulsion: Multi-frequency ultrasound regulation, characterization and its application in quercetin delivery

This study used dual-frequency countercurrent probe ultrasound (DFU) to prepare sodium caseinate (Cas)-Pectin (Pec) complex-stabilized emulsion. Besides analyzing the physicochemical properties and structural characteristics, the current study assessed the impact of DFU on the encapsulation efficiency (EE), bioavailability, antioxidant activity , and stability of quercetin (QUE)-loaded emulsions. The results indicated that DFU (20/28 kHz) improved the emulsion resistance to environmental stress by increasing the interaction between the lipid-complex and decreasing the droplet size (from 12.60 to 3.09 μm), mainly manifesting the higher stability index (improved to 97%). Furthermore, DFU enhanced the interface Cas/Pec adsorption than high-speed shear homogenization (improved from 3.55 to 6.29 mg/m 2 for Cas and from 3.28 to 5.83 mg/m 2 for Pec) and exhibited better uniformity. The aforementioned enhancements exhibited a positive impact on emulsion loading QUE, improving its EE (from 69 to 83%) and increasing its bioavailability (from 12% to 48%). Furthermore, emulsion stability was improved through the reduction of free radical production and QUE degradation induced by environmental factors.