Encapsulation of quercetin in zein/sodium caseinate nanoparticles: Fabrication, characterization, stability and...

The poor stability and low bioavailability of quercetin (Que) have limited its application in the food industry. Que-loaded zein/sodium caseinate (SC) nanoparticles were prepared at different zein/SC mass ratios. The aggregated nanoparticles at low SC concentrations due to weak electrostatic repulsion, while a zein/SC ratio of 1:4 produced well-dispersed nanoparticles with high encapsulation efficiency and good stability. The hydrogen bonding, electrostatic interactions, and hydrophobic associations contributed to the successful encapsulation of Que. and the transformation of Que. into an amorphous form. Stability tests revealed that SC markedly improved the resistance of Que. to environmental stresses, with the best performance observed at zein/SC ratios of 1:4 and 1:8. Furthermore, an improved re-dispersibility of the nanoparticles was found after addition of SC. In vitro gastrointestinal digestion showed that higher SC levels modulated a sustained release of Que. Overall, zein-SC nanoparticles provided an effective delivery system for protecting and enhancing the functional properties of Que., offering potential applications in functional foods and nutraceutical formulations.