Sodium caseinate decorating on shellac nanoparticles as a stabilizer for the encapsulation of quercetin

• The effects of sodium caseinate on the stability of SNPs were investigated. • The optimal concentration for sodium caseinate decorating SNPs was 0.3%. • SQCNPs were fabricated based on hydrophobic and hydrogen-bonding interactions. • The decoration of sodium caseinate improved the functional properties of SNPs. To protect quercetin and address some of the barriers about shellac as a delivery carrier, we investigated the effects of sodium caseinate surface decoration on the formation, stability, and physiochemical properties of shellac nanoparticles (SNPs) for the first time. Herein, 0.3% caseinate was selected to prepare the quercetin-loaded shellac/sodium caseinate complex nanoparticles (SQCNPs), ensuring stable formation of nanoparticles and preventing irreversible aggregation of SNPs in acid. Fourier transform infrared spectroscopy and complex nanoparticle dissociation test indicated SQCNPs were fabricated based hydrophobic and hydrogen-bonding interactions among Que, shellac, and caseinate. Besides, the modification of sodium caseinate can address salt instability and low redispersibility and improve encapsulation efficiency of SNPs. Meanwhile, SQCNPs possessed good antioxidant capacity, low cytotoxicity and controlled release in simulated gastrointestinal digestion. In summary, this work might open up a new, green, and sustainable method to design a bioactive substance delivery system by employing shellac as a vehicle.