Enterocyte and M-cell transport of native and heat-denatured bovine β-lactoglobulin : significance of heat denaturation

The three-dimensional structure, digestibility, and immunological properties of bovine β-lactoglobulin (β-lg) are modified by heat treatments used in processing of liquid milk products. Because it is not known if such treatments also modify the intestinal transport properties of β-lg, the transport of native and heat-denatured bovine β-lg was investigated in experimental cell models using Caco-2 cells and M cells. Transport of β-lg labeled with a fluorescent marker was followed with fluorometric measurements, electrophoretic analyses, and fluorescence microscopy. The data show that both cell types transported native β-lg more efficiently than they did heat-denatured β-lg. In addition, M cells transported native β-lg more than Caco-2 cells. Transport of native and heat-denatured β-lg was transcellular. The electrophoretic data also suggest that heat-denatured β-lg may have degraded more than native β-lg during the transport.