Construction and Characterization of Quercetin-loaded Enzymatic Glycosylated Casein Composite Nanoparticles

In this study, glycosylated composite nanoparticles were prepared by transglutaminase glycosylation to modify casein (Cas), and quercetin (Que) was embedded with nanoparticles to investigate its stabilization effect on Que. Enzymatic glycosylation was used to conjugate Chito-oligosaccharides (Cos) into Cas, and casein-chito-oligosaccharides composite nanoparticles (_n-Cas-Cos) were constructed by ultrasonic self-assembly method. Que was embedded with Cas and casein-chito-oligosaccharides to form quercetin nanoparticles (_n-Cas-Que and _n-Cas-Cos-Que).The appearance, micro morphology and binding mechanism of the quercetin nanoparticles were analyzed by Transmission electron microscopy (TEM), Fourier transform infrared spectrum (FITR) and X-ray diffractometer (XRD). The thermal stability of quercetin nanoparticles was investigated at 37, 60 (pasteurized) and 99 ℃ (boiling) conditions. The results showed that when the pH was 5.8, the ultrasonic power was 200 W, and the concentration of glycosylated products was 4 g/L, the average particle size (Dz) of _n-Cas-Cos was the smallest, which was 125.6 nm. After loading with Que, the encapsulation efficiency (EE) of _n-Cas-Que and _n-Cas-Cos-Que were 74.14% and 85.21% respectively. Besides, the quercetin nanoparticles were spherical under transmission electron microscopy, and there was no significant difference between the nanoparticles before and after embedding Que. At 37, 60 and 99 ℃, the casein-chito-oligosaccharide composite nanoparticles loaded with Que showed better thermal stability, the retention rates of Que were 87.6%, 63.5% and 5.13% respectively.