Fabrication of curcumin-loaded whey protein microgels: Structural properties, antioxidant activity, and in vitro release behavior

This study evaluated the potential use of whey protein microgels (WPM) formed by heating a protein solution at pH 5.90 as carriers for curcumin. The results indicated that the loading amount of curcumin into whey protein isolate (WPI) and WPM was 1.84 +/- 0.18 and 17.51 +/- 0.46 mu g curcumin/mg protein, respectively. Loading of microgels with curcumin significantly increased their diameter and changed their surface charge. Loading of curcumin in the whey protein microgels drastically decreased its sedimentation during storage. Fluorescence measurements revealed that the curcumin was present at the hydrophobic core of whey protein microgels. X-ray diffraction analysis also showed that curcumin was loaded inside the WPM in an amorphous form. Curcumin-loaded whey protein microgels showed a high in vitro antioxidant activity which was measured by DPPH radical scavenging and reducing power assay. The in vitro release experiment also showed that the release of curcumin from WPM was significantly slower than WPI during the simulated gastrointestinal conditions. These findings suggested a possible utilization of WPI microgels in improving the applications of curcumin for the production of functional food products and drugs.