title: Polyphenol-beta-casein complexes at the air/water interface and in solution: effects of polyphenol structure.
abstract: The interactions between proteins and plant polyphenols are responsible for astringency and haze formation in beverages and may participate in foam stabilization. The effect of phenolic compounds with different structures, namely, catechin (C), epicatechin (Ec), epigallocatechin (Egc), epicatechin gallate (EcG), and epigallocatechin gallate (EgcG), on the surface properties at the air/liquid interface of beta-casein, chosen as model protein, were monitored by tensiometry and ellipsometry. The formation of complexes in the bulk phase was measured by electrospray ionization mass spectrometry (ESI-MS). Adsorption of polyphenols from pure solution was not observed. Surface pressure, surface concentration, and dilational modulus of the protein adsorption layer were greatly modified in the presence of galloylated flavanol monomers (EcG and EgcG) but not of lower molecular weight polyphenols (<306 g/mol). The formation of polyphenol-protein aggregates in the bulk, as evidenced by ESI-MS and light scattering experiments, was related to the slowdown of protein adsorption.
authors.affiliation: INRA UMR 614 Fractionnement des Agro-Ressources et Environnement (FARE) INRA/Universite de Reims Champagne Ardennes, Centre de Recherche en Environnement et Agronomie, 2 Esplanade R. Garros, BP 224, F-51686 Reims, France. Veronique.Aguie@reims.inra.fr
authors.forename: V
authors.initials: V
authors.lastname: Aguié-Béghin
authors.forename: P
authors.initials: P
authors.lastname: Sausse
authors.forename: E
authors.initials: E
authors.lastname: Meudec
authors.forename: V
authors.initials: V
authors.lastname: Cheynier
authors.forename: R
authors.initials: R
authors.lastname: Douillard
mesh_terms: D002364:Caseins / Q000737:chemistry*; D005419:Flavonoids / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry*; D059808:Polyphenols; D021241:Spectrometry, Mass, Electrospray Ionization; D013499:Surface Properties
chemical_list: D002364:Caseins; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols