Physicochemical properties of casein-dextran nanoparticles prepared by controlled dry and wet heating.

Casein-dextran nanoparticles (CDNs) were prepared from casein-dextran conjugates by heating in a dry/wet state and then adjusting the pH to the isoelectric point of the protein (pH 4.6) to investigate their physicochemical characteristics. The effects of the dry and wet heating methods on the properties of the CDNs were also evaluated. The CDNs were spherically shaped and uniformly dispersed, as confirmed by atomic force microscopy. Compared with CDNs prepared by wet heating (CDN-W), those prepared by dry heating (CDN-D) were much smaller (P<0.05) and showed superior stability and enhanced the release of curcumin under simulated gastrointestinal conditions. However, both types exhibited the same encapsulation ability of curcumin. Meanwhile, the CDNs displayed good thermal, gastrointestinal and storage stability, and good redispersion behaviour. Our findings indicated CDN-D exhibited superior physicochemical properties and could serve as a potential delivery vehicle to encapsulate hydrophobic active ingredients to intestine.