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 433357
Title Interfacial properties of air/water interfaces stabilized by oligofructose palmitic acid esters in the presence of whey protein isolate
Author(s) Kempen, S.E.H.J. van; Maas, K.; Schols, H.A.; Linden, E. van der; Sagis, L.M.C.
Source Food Hydrocolloids 32 (2013)1. - ISSN 0268-005X - p. 162 - 171.
Department(s) Physics and Physical Chemistry of Foods
Food Chemistry
Publication type Refereed Article in a scientific journal
Publication year 2013
Keyword(s) air-water-interface - beta-lactoglobulin - competitive adsorption - rheological properties - surfactant systems - dynamic properties - foaming properties - liquid interfaces - mixed films - displacement
Abstract To study the applicability of oligofructose palmitic acid esters (OF-C16) as novel surfactants in food systems, the functional properties of OF-C16 were studied in the presence of whey protein isolate (WPI). Surface tension measurements, surface dilatational rheology, foam stability tests and Brewster Angle Microscopy were used to study the competitive adsorption of WPI and OF-C16 and the displacement of WPI by OF-C16. Pure WPI stabilized interfaces had a moderate surface tension (48 mN/m) and a dilatational modulus of 90 mN/m, while pure OF-C16 stabilized interfaces had a low surface tension (30 mN/m) and a dilatational modulus of 50 mN/m. The stabilization mechanisms of WPI (elastic network formation) and of OF-C16 (surface solidification) are very different, and the combined adsorption of these two components led to a structure with a much lower dilatational modulus. At the lowest WPI concentrations (0.5% and 1%), the equilibrium surface tension was similar to a pure OF-C16 stabilized interface, pointing to a low WPI surface concentration. However, apparently still sufficient WPI had adsorbed either at or just below the interface, to prevent the OF-C16 from solidifying. Despite the low moduli, the foam stability for the mixed systems was high. The interfaces were probably stabilized by the Gibbs-Marangoni mechanism. In contrast, at the highest WPI concentration (2%), the equilibrium surface concentration of WPI was sufficiently high to decrease the interfacial mobility of OF-C16, which decreased the Gibbs-Marangoni effect and resulted in decreased foam stability. Finally, OF-C16 could also displace a fully developed WPI network from the interface.
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