Surface behaviour of adsorbed films from protein-amphiphile mixtures

Abstract

The effect of interaction between proteins and amphiphiles on the surface tension reduction have been measured by the drop-volume method. The equilibrium surface tension reduction isotherms at the air/water interface of serum albumin and of ovalbumin in sodium dodecylsulphate and of ovalbumin in l-monocaproin are reported. The surface tension reduction isotherms of the proteins in the anionic amphiphile solutions exhibit plateau regions, which have been interpreted in terms of different states of protein-amphiphile interaction in the bulk solution. Any interaction between ovalbumin and the monoglyceride is not reflected in the surface tension isotherm. At increased amphiphile concentration the protein seems to be replaced by 1-monocaproin in the surface.

Surface tension of protein and insoluble lipids at the air‐aqueous phase interface

“…The interfacial behavior analyzed previously is practically similar to that observed with monocaproin + ovalbumin (18) and with mono-and diglycerides and casein (19). As a consequence of these results, we can speculate that, at higher BSA relative concentrations in BSA-lipid mixed systems, the surface activity is determined by the protein.…”

“…There have been many studies of protein-lipid interactions in relation to the formation and stability of food emulsions and foams. Several groups have studied the interactions between proteins and soluble lipids (14)(15)(16)(17), but much less is known about the details of protein-insoluble lipid interactions (8,18,19). In previous papers, we studied the interfacial characteristics-surface rheological properties, drainage, and diffusion in thin films-of protein-lipid mixed films as a function of interfacial and aqueous phase compositions (20)(21)(22)(23).…”

Food Emulsifiers and Their Applications

“…5.7b), a gradual decrease of the surface tension with increasing surfactant concentration is observed. This might be assigned to the more efficient packing in the formed mixed surfactant /protein layer compared to the one formed by the individual components at this concentration (Ericsson and Hegg, 1985). Even at the lowest concentration of cationic surfactant (0.05 mole HPC per mole ovalbumin), where the pure surfactant has the same surface tension as water, a decrease in surface tension for the protein surfactant mixture, compared to pure ovalbumin, is observed (Fig.…”

“…The surface tension value after 2000 s has been used for the isotherms. Further details are given elsewhere (Ericsson and Hegg 1985) which is observed at increased surfactant concentration is likely to be connected with saturation of the cooperative binding sites. As surfactant concentration further increases the surface tension isotherms for the two protein surfactant mixtures coincide.…”

“…Surface tension measurements have often been used to study protein-lipid interaction, (cf., Nishikido et al, 1982;Ericsson and Hegg, 1985;Fainerman et al, 1998;Miller et al, 2000a;Vollhardt and Fainerman, 2000). However, it must be born in mind that any impurity with higher surface activity than the studied components will accumulate at the interface giving a lowering of the surface tension (Miller and Lunkenheimer, 1986;Lunkenheimer and Miller, 1987;Lunkenheimer and Czichocki, 1993) and thus affect the interpretation of the data.…”