Covalent grafting of corn stover cellulose nanofibers with zein for pickering emulsion stabilization and controlled quercetin delivery

Enhancing hydrophobic bioactives' bioaccessibility remains challenging in functional foods due to instability and insufficient controlled-release ability in conventional protein-polysaccharide carriers. We pioneer a new interaction model by covalently grafting corn stover cellulose nanofibers (CNF) with Zein using N-(3-dimethylaminopropyl)-N′-ethyl carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), creating conjugates with gradient grafting degrees (CNF/Zein 0.5, CNF/Zein 1, and CNF/Zein 2). Excitingly, compared to the non-covalent complex (CNF-Zein), conjugates exhibited a stable network-like microstructure, lower crystallinity, and enhanced thermal stability. Furthermore, the conjugates exhibited excellent amphiphilicity, forming denser and more stable emulsions. Confocal laser scanning microscope (CLSM) revealed a dual stabilization mechanism of “interface adsorption-network encapsulation”. Additionally, CNF/Zein-stabilized emulsions demonstrated controlled quercetin release and improved bioaccessibility during in vitro digestion tests, with the highest grafted CNF/Zein 2 showing 43.65 % bioaccessibility. This study first demonstrates the effectiveness of the EDC/NHS technique in alcohol-solution systems, providing novel strategies for conjugate design and lipophilic nutraceutical delivery.