Adsorption Experiments from Mixed Protein + Surfactant Solutions - Food Colloids: Self-Assembly and Material Science - page 209

Chapter 14
Adsorption Experiments from Mixed
Protein + Surfactant Solutions
Veneta S. Alahverdjieva, 1 Dmitry O. Grigoriev, 1 James K.
Ferri, 2 Valentin B. Fainerman, 3 Eugene V. Aksenenko, 4 Martin
E. Leser, 5 Martin Michel 5 and Reinhard Miller 1
1 MAX-PLANCK-INSTITUT FU ¨ R KOLLOID- UND GRENZFLA ¨ CHEN
FORSCHUNG, AM MU ¨ HLENBERG 1, 14424 POTSDAM, GERMANY
2 DEPARTMENT OF CHEMICAL ENGINEERING, LAFAYETTE
COLLEGE, EASTON, PA 18042, USA
3 MEDICAL PHYSICOCHEMICAL CENTRE, DONETSK MEDICAL
UNIVERSITY, 16 ILYCH AVENUE, 83003 DONETSK, UKRAINE
4 INSTITUTE OF COLLOID CHEMISTRY AND CHEMISTRY OF
WATER, 42 VERNADSKY AVENUE, 03680 KIEV, UKRAINE
5 NESTLE ´ RESEARCH CENTER, VERS-CHEZ-LES-BLANC, CH-1000
LAUSANNE 26, SWITZERLAND
14.1 Introduction
There is great practical importance in the study of the adsorption of proteins
with or without surfactants at fluid interfaces for a wide range of areas, such
as food foams and emulsions, 1 cosmetics, coating processes, 2 pharmacy and
biotechnology. This has led to the development of various theoretical models
which describe the equilibrium and dynamic behaviour of protein adsorption
layers. The properties of protein adsorption layers differ in many aspects
from those characteristicofsimplesurfactants. 3 First,foraprotein,surface
denaturation may occur, leading to the unfolding of the protein molecule
within the surface layer, at least at low surface pressure. In contrast to
surfactants, the partial molar surface area for proteins is large and it can
vary. This feature, and also the fact that the number of configurations for an
adsorbed protein molecule exceeds significantly that of the protein molecules
in the bulk, leads to a significant increase in the non-ideality of the surface
layer entropy. This also makes it impossible to apply the simplest models (i.e.,
Henry and Langmuir isotherms) to the description of protein adsorption
layers.
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