Improvement of curcumin loading properties and bioaccessibility of beta-lactoglobulin-hyaluronic acid nanocomplexes conjugated via ultrasound-assisted Maillard reaction.

Curcumin (Cur) has many potential applications in the food industry. However, it suffers from poor water solubility, low plasma and tissue uptake and susceptibility to oxidation. In this study, β-lactoglobulin (β-LG)-hyaluronic acid (HA) binary covalent complexes were prepared by ultrasound-assisted Maillard reaction and used as the carrier to deliver Cur. Results of SDS-PAGE, degree of grafting, and SEM showed that β-LG was successfully grafted to HA, and the degree of grafting increased from 15.30 ± 0.28 % to 29.70 ± 0.45 % under ultrasound treatment. There was a decrease in α-helix and β-sheet contents, and an increase in random coil content, and the amide I bands, and tryptophan motifs in the covalent secondary and tertiary structures of the nanocomplexes. Encapsulation by β-LG-HA could form the controlled release of Cur, resulting in a decreased release rate in the oral and gastric phases and an increased release rate in the intestinal phase, as demonstrated in an in vitro digestion simulation. Furthermore, the β-LG-HA-Cur nanocomplex exhibited the superior antioxidant and enzyme inhibition of α-amylase and α-glucosidase. The inhibition rates of α-amylase and α-glucosidase could reach 48.91 ± 0.81 % and 49.88 ± 0.61 %, respectively. This study will help to understand the ultrasound-assisted Maillard reaction covalent binding of protein- polysaccharides complexes, demonstrate the potential for Cur delivery, and develop functional dairy products with hypoglycemic activity.