Enhanced stability and bioavailability of astaxanthin via piperine co-encapsulation in whey protein fibril- sodium...

This study developed a dual-delivery system for astaxanthin (AST) and piperine (Pip) by complexing sodium alginate (SA) with whey protein fibrils (WPF) to enhance AST stability and bioavailability. Hydrophobic Pip was first loaded onto WPF followed by electrostatic complexation with SA at pH 5.0 to form soluble composites for AST encapsulation. Using a solvent extraction method, the results demonstrated that the optimized WPF/SA (1: 2) system achieved an exceptional AST encapsulation efficiency of 99.39 % and outstanding storage stability, with only a 7.5 % increase in particle size after 28 days. SA addition markedly increased emulsion viscosity (W(P)/SA(1:2)-E: 4.913 Pa∙s), forming a dense network. The system effectively resisted bile salt displacement (5 mg/mL) and minimal change in zeta-potential (Δζ = 0.60 mV), representing an 83.56 % reduction versus unmodified emulsions. During in vitro digestion, it achieved a free fatty acid release rate of 91.85 % ± 2.67 % and an AST bioaccessibility of 72.17 % ± 1.03 %, which was 11.5-fold that of free AST in oil. With Pip's bioenhancing effect, the Caco-2 cellular absorption of AST reached 37.47 % ± 1.54 %, a 2.78-fold increase over the non-Pip loaded group. This study provided a strategy to improve the stability and bioavailability of lipophilic bioactives.