Liquid droplet-like behaviour of whole casein aggregates adsorbed on graphite studied by nanoindentation with AFM
Author
Summary, in English
AFM measurements in the force volume mode were performed over the total penetration depth for different positions on casein aggregates adsorbed to a graphite surface in a liquid cell. The stiffness of the force curves was correlated to indentation depths, layer depth and lateral position within the aggregates with the aim of arriving at a credible explanation for the shapes of the force curves. The commonly used Hertz-based models did not fit the experimental data. The ratio between the height and diameter of the adsorbed casein aggregates was found to be linear, suggesting surface energy dominated liquid droplet behaviour. To investigate the possibility, numerical simulations were performed using the Surface Evolver, an interactive finite element program for the study of surfaces shaped by surface tension and other energies. Simulated force curves were in good agreement with experimental findings, both with respect to slope as a function of indentation as well as describing the variation with indentation position on the aggregate due to interfacial and geometric effects. By comparing the simulated force curves to the measurement data it was found that there would have been an interfacial energy equivalent to 10 mJ/m2.
Department/s
- Department of Food Technology, Engineering and Nutrition
Publishing year
2007
Language
English
Pages
726-738
Publication/Series
Food Hydrocolloids
Volume
21
Issue
5-6
Full text
- Available as PDF - 711 kB
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Document type
Journal article
Publisher
Elsevier
Topic
- Food Science
Keywords
- CaseinNanorheologyAdsorptionAFMSurface evolverModelling
Status
Published
ISBN/ISSN/Other
- ISSN: 0268-005X