Complexes of black kidney bean protein, pectin, and quercetin as potential antioxidant food ingredients: Fabrication and characterization.

This study developed non-covalent complexes of black kidney bean protein isolate (BBPI), pectin (PEC), and quercetin (Que) as nutraceutical delivery systems. The optimized Que-BBPI-PEC (mass ratio 0.1:3:1) exhibited a particle size of 479.73 nm (PDI = 0.38) with 94.72 % Que encapsulation efficiency. Electrostatic and hydrogen bonding primarily governed BBPI-PEC interactions, while Que integrated spontaneously at a single binding site, driven by hydrogen bonding and hydrophobic interactions. Overall, the amorphous Que-BBPI-PEC significantly enhanced Que stability under UV exposure, heat, and storage, achieving retention rates of 22.29 %, 35.05 %, and 22.04 %, and displayed superior antioxidant ability, with DPPH• radical and ABTS•+ radical scavenging rates of 60.79 % and 55.26 %, respectively. Que-BBPI-PEC significantly reduced Que dissolution and decomposition in the stomach, achieving only 58.15 % release during in vitro digestion, much lower than free Que. This study elucidates complex formation mechanism and preparation parameters, highlighting potential as delivery carriers for phenolic compounds and functional food additives.