Increased stability and protease resistance of the β-lactoglobulin/vitamin D3 complex

The stability of the beta-lactoglobulin (beta lg)/vitamin D-3 (D-3) complex at 4 degrees C and upon exposure to UV-C light, and in simulated intestinal fluid, were studied in vitro. Caco-2 cells were used to demonstrate the passage of the beta lg/D-3 complex across the monolayers. Furthermore, an in vivo experiment was conducted by force-feeding rats with the free D-3 and beta lg/D-3 complex, with subsequent determination of the plasma concentration of 25-hydroxy-D-3. The beta lg/D-3 complex significantly improved the stability of the vitamin at 4 degrees C and when exposed to UV-C light. The resistance of pig to proteases was increased, indicating a mutual protective effect. The beta lg/D-3 complex crossed the monolayers, which was confirmed by the significant increase in the concentration of 25-hydroxy-D-3 in rats fed the beta lg/D-3 complex compared to the ones fed the free D-3. Therefore, the current study suggests that the beta lg/D-3 complex can effectively be used for the fortification of milk products and low-fat content foods to improve the intake and bio-availability of D-3. (C) 2013 Elsevier Ltd. All rights reserved.