In vitro release of α-tocopherol from emulsion-loaded β-lactoglobulin gels

Cold-set oil-loaded protein gels based on an emulsifying step followed by Ca2+-induced gelation of pre-denatured β-lactoglobulin (β-LG) have been recently developed. In vitro release and stability of a fat-soluble compound (α-tocopherol) therein were investigated in this work. Release of α-tocopherol was found to be controlled mainly by matrix erosion due to protein degradation. Compound release and matrix erosion were almost complete after incubation under gastric or intestinal conditions for 6.5 h. However, both processes were basically inhibited upon changing the dissolution medium from the gastric to the intestinal type, possibly due to β-LG partial hydrolysis products with greater emulsifying capacity anchoring to the surface of gel oil droplets. The stability of released α-tocopherol was apparently improved by binding to protein and/or hydrolysis products thereof.