Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 35684
Title Comparison of the dilational behaviour of adsorbed milk proteins at the air-water and oil-water interfaces.
Author(s) Williams, A.; Prins, A.
Source Colloids and Surfaces. A: Physicochemical and Engineering Aspects 114 (1996). - ISSN 0927-7757 - p. 267 - 275.
Department(s) Integrated Food Science and Food Physics
Publication type Refereed Article in a scientific journal
Publication year 1996
Abstract The interfacial dilational properties of two milk proteins, β-casein and β-lactoglobulin, have been compared at the air-water and paraffin oil-water interfaces. The measurements were performed as a function of bulk protein concentration using a modified Langmuir trough technique at a frequency of 0.1 Hz. It appears that the dilational properties of the two proteins are essentially the same whether the upper phase is paraffin oil or air. This is attributed to rather limited penetration of the oil phase by the protein molecules. The interfacial properties have been shown to be dependent upon the bulk concentration of the protein. This, together with the history of the surface, presumably determines the interfacial concentration and conformation of the protein molecules. At low bulk concentrations both the modulus and the loss tangent are similar for the two proteins. It is conjectured that both proteins have a similar, reasonably extended, structure in the interface. At higher bulk concentrations the behaviour of the two proteins diverges. The interfacial dilational modulus for β-lactoglohulin is around 62 mM m-1 for bulk concentrations ≤ 3 x 10-2 g l-1, and the viscosity of the surface is rather low. It is postulated that this protein forms a cohesive elastic network within the interface. The interfacial dilational modulus for β-casein at similar concentrations is around 13 mM m-1. It is thought that some intermolecular cohesion is present in the interface, but that this is much weaker than for the globular protein. High concentrations of β-casein impart significant dilational viscosity to the interface, due either to diffusional relaxation or to rearrangement of the adsorbed primary layer and multilayers of protein.
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