Zein-coated versus zein-inserted kaempferol liposomes: enhancing bitterness masking, stability, and bioaccessibility

Kaempferol, a plant flavonoid with antioxidant, anti-inflammatory, and anti-allergenic bioactivities, has limited use in functional foods due to its bitterness and low bioavailability. This study compared two zein-based modification strategies, insertion and coating, for kaempferol-loaded liposomes in terms of bitterness masking, stability, and bioaccessibility. At 0.2 mg/mL zein, insertion showed 4.67% higher encapsulation efficiency than coating. (P < 0.05). E-tongue analysis showed coating reduced bitterness more effectively than insertion. Raman spectroscopy revealed coating involved electrostatic interactions, while insertion involved hydrophobic ones. Fluorescence probing indicated insertion expanded liposome internal space, whereas coating resulted in a compact structure. TG and DSC analyses confirmed coating provided greater thermal stability. Additionally, coated liposomes exhibited superior environmental stability, antioxidant activity, and bioaccessibility. In vitro tests showed zein-coated liposomes released 62.98 ± 1.35% kaempferol, while zein-inserted liposomes released 50.32 ± 0.59%. These findings offer new insights for integrating bitter bioactives into functional foods.