Formation and characterization of quercetin-loaded chitosan oligosaccharide/β-lactoglobulin nanoparticle

Food grade materials including chitosan and β-lactoglobulin need to be developed for the application of nanoparticles to food science. It is hypothesized that hydrophobicity of chitosan oligosaccharide and β-lactoglobulin may be a key factor to affect the physicochemical properties of nanoparticle. The aim of this study was to investigate how substitution of chitosan oligosaccharide with linoleic acid (LA) and sub-ambient temperature treatment, which can influence hydrophobicity, affect the formation and physicochemical properties of LA-modified chitosan oligosaccharide/β-lactoglobulin (CSO-LA/β-lg) nanoparticles. CSO-LAs with different charged amounts of LA (0, 10, 20, and 30%) and β-lg mixtures at pH 4.4 were sub-ambient temperature treated at 5, 10, 15, and 20 °C for 30 min followed by treatment with 0.5 mM tripolyphosphate. Quercetin was used as a model hydrophobic bioactive compound. Spherical shape nanoparticles in the range of 170 and 350 nm were successfully formed. An increase in charged amount of LA and temperature resulted in an increase in the size of CSO-LA/β-lg nanoparticles. Increasing charged amount of LA and decreasing sub-ambient temperature treatment led to an increase in the association efficiency of CSO and β-lg, respectively. Encapsulation efficiency of quercetin was enhanced with increased charged amount of LA and decreased temperature. It was concluded that charged amounts of LA and sub-ambient temperature were major key-factors affecting the size of nanoparticles and encapsulation efficiency of quercetin.