title: Interfacial properties, thin film stability and foam stability of casein micelle dispersions.
abstract: Foam stability of casein micelle dispersions (CMDs) strongly depends on aggregate size. To elucidate the underlying mechanism, the role of interfacial and thin film properties was investigated. CMDs were prepared at 4°C and 20°C, designated as CMD4°Cand CMD20°C. At equal protein concentrations, foam stability of CMD4°C(with casein micelle aggregates) was markedly higher than CMD20°C(without aggregates). Although the elastic modulus of CMD4°Cwas twice as that of CMD20°Cat 0.005Hz, the protein adsorbed amount was slightly higher for CMD20°Cthan for CMD4°C, which indicated a slight difference in interfacial composition of the air/water interface. Non-linear surface dilatational rheology showed minor differences between mechanical properties of air/water interfaces stabilized by two CMDs. These differences in interfacial properties could not explain the large difference in foam stability between two CMDs. Thin film analysis showed that films made with CMD20°Cdrained to a more homogeneous film compared to films stabilized by CMD4°C. Large casein micelle aggregates trapped in the thin film of CMD4°Cmade the film more heterogeneous. The rupture time of thin films was significantly longer for CMD4°C(>1h) than for CMD20°C(<600s) at equal protein concentration. After homogenization, which broke down the aggregates, the thin films of CMD4°Cbecame much more homogeneous, and both the rupture time of thin films and foam stability decreased significantly. In conclusion, the increased stability of foam prepared with CMD4°Cappears to be the result of entrapment of casein micelle aggregates in the liquid films of the foam.
authors.affiliation: Top Institute Food and Nutrition, P.O. Box 557, 6700 AN Wageningen, The Netherlands; Wageningen University, Physics and Physical Chemistry of Foods, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.affiliation: Top Institute Food and Nutrition, P.O. Box 557, 6700 AN Wageningen, The Netherlands; Wageningen University, Physics and Physical Chemistry of Foods, P.O. Box 17, 6700 AA Wageningen, The Netherlands; Wageningen UR, Food and Biobased Research, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Guido
authors.initials: G
authors.lastname: Sala
authors.affiliation: Top Institute Food and Nutrition, P.O. Box 557, 6700 AN Wageningen, The Netherlands; Wageningen UR, Food and Biobased Research, P.O. Box 17, 6700 AA Wageningen, The Netherlands. Electronic address: marcel.meinders@wur.nl.
authors.forename: Marcel B J
authors.initials: MB
authors.lastname: Meinders
authors.affiliation: Wageningen University, Food Quality and Design, Dairy Science and Technology, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Hein J F
authors.initials: HJ
authors.lastname: van Valenberg
authors.affiliation: Top Institute Food and Nutrition, P.O. Box 557, 6700 AN Wageningen, The Netherlands; Wageningen University, Physics and Physical Chemistry of Foods, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Erik
authors.initials: E
authors.lastname: van der Linden
authors.affiliation: Wageningen University, Physics and Physical Chemistry of Foods, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Leonard M C
authors.initials: LM
authors.lastname: Sagis
mesh_terms: D000327:Adsorption; D002364:Caseins / Q000737:chemistry*; D055119:Elastic Modulus; D005427:Flocculation; D008823:Micelles; D012212:Rheology; D013499:Surface Properties; D013535:Suspensions; D014867:Water / Q000737:chemistry*
chemical_list: D002364:Caseins; D008823:Micelles; D013535:Suspensions; D014867:Water
keywords: Casein micelle aggregates; Foam; Surface rheology; Thin film stability