Lipases at interfaces : a review

Milk protein interfacial layers and the relationship to emulsion stability and rheology.

β-Lactoglobulin and WPI aggregates: Formation, structure and applications

Structural and functional changes in ultrasonicated bovine serum albumin solutions.

In this paper, recent progress in our knowledge of how the interface influences the formation and stability of emulsions has been reviewed. Attention was focused on the effect of molecular structure, interfacial rheology, competitive adsorption and interfacial structure and composition.

Interfaces: their role in foam and emulsion behaviour

Effect of thermal treatment on interfacial properties of β-lactoglobulin

Dynamics of adsorption of 14C radiolabeled beta-lactoglobulin and alpha-lactalbumin at the air-water interface was investigated through the measurement of surface pressure (pi) and surface concentration (Gamma) via a radiotracer technique. Adsorption was diffusion controlled at short times, the rates of increase of pi and Gamma being lower at longer times because of an energy barrier. At low concentrations, an apparent time lag was observed in the evolution of pi for beta-lactoglobulin but not for alpha-lactalbumin which was shown to be due to the nonlinear nature of the pi-Gamma relationship for the former. The area per molecule of an adsorbed beta-lactoglobulin during the dynamics of adsorption was smaller than that for spread monolayer since beta-lactoglobulin was not fully unfolded during adsorption. For alpha-lactalbumin, however, no such difference in the molecular areas for adsorbed and spread monolayer was observed indicating thereby that alpha-lactalbumin unfolded much more rapidly than beta-lactoglobulin. Evolution of Gamma for alpha-lactalbumin was found to occur in two steps possibly due to the change in the orientation of the adsorbed protein from a side-on to an end-on orientation. A previously developed mechanistic model (G. Narsimhan and F. Uraizee, Biotechnology Prog. 8, 187 (1992)) was improved to account for the presence of hydrophobic patches on the surface of the protein molecule as well as an adsorbed protein layer at the air-water interface. The model predictions agreed quite well with the experimental evolution of Gamma for beta-lactoglobulin and alpha-lactalbumin. The model calculations seem to indicate that alpha-lactalbumin changes its orientation at the air-water interface from side-on to other orientations at higher surface concentrations. Copyright 1999 Academic Press.

Adsorption Dynamics of α-Lactalbumin and β-Lactoglobulin at Air–Water Interfaces

Adsorption dynamics and interfacial properties of α-lactalbumin in native and molten globule state conformation at air–water interface

Spread monolayer isotherms of β-lactoglobulin, monopalmitin, monolaurin, and their mixtures were measured at the air−water interface. The isotherms exhibited hysteresis behavior. A phase transition...

Adsorption and Exchange of β-Lactoglobulin onto Spread Monoglyceride Monolayers at the Air−Water Interface

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.

Michel Cornec

Papers

Effect of thermal treatment on interfacial properties of β-lactoglobulin

Adsorption Dynamics of α-Lactalbumin and β-Lactoglobulin at Air–Water Interfaces

Adsorption dynamics and interfacial properties of α-lactalbumin in native and molten globule state conformation at air–water interface

Adsorption and Exchange of β-Lactoglobulin onto Spread Monoglyceride Monolayers at the Air−Water Interface

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