Showing papers by "Ganesan Narsimhan published in 1998"

Effect of contaminant on adsorption of whey proteins at the air-water interface

Abstract: The dynamics of adsorption of commercial samples of α-lactalbumin and β-lactoglobulin was investigated through the measurement of dynamic surface pressure and surface concentration via a radiotracer method. An unusual two-step adsorption behavior was observed for both proteins at low concentration which was believed to be due to the presence of a surface active contaminant. This hypothesis was tested by comparing the native whey protein samples with those purified with charcoal extraction. Analysis of the charcoal extract by thin-layer chromatography revealed the presence of contaminating free fatty acid and triglycerides in the commercial samples. β-Lactoglobulin was found to contain a higher concentration of these contaminants than α-lactalbumin. Extraction by charcoal was found not to modify the protein structure with respect to their near-and far-UV circular dichroism spectra. The presence of contaminant resulted in a higher steady-state surface pressure for β-lactoglobulin, but the protein was not displaced from the interface. On the other hand, the presence of a low concentration of surfactant was sufficient to decrease the steady-state surface concentration of α-lactalbumin due to the displacement of the protein from the interface by the lipids.