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Liquid droplet-like behaviour of whole casein aggregates adsorbed on graphite studied by nanoindentation with AFM

Helstad, Kristina LU ; Rayner, Marilyn LU ; van Vliet, Ton; Paulsson, Marie LU and Dejmek, Petr LU (2007) In Food Hydrocolloids 21(5-6). p.726-738
Abstract
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... (More)
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. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
CaseinNanorheologyAdsorptionAFMSurface evolverModelling
in
Food Hydrocolloids
volume
21
issue
5-6
pages
726 - 738
publisher
Elsevier
external identifiers
  • wos:000245790200007
  • scopus:33947120643
ISSN
0268-005X
DOI
10.1016/j.foodhyd.2006.10.006
language
English
LU publication?
yes
id
59546161-fe48-4bab-a3c4-f5bfd4ac174a (old id 540391)
alternative location
http://www.sciencedirect.com/science/article/B6VP9-4MKTY0Y-1/2/a169993a235a30ea5a352d9a1aff1a39
date added to LUP
2007-12-03 10:42:48
date last changed
2017-06-04 03:40:56
@article{59546161-fe48-4bab-a3c4-f5bfd4ac174a,
  abstract     = {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.},
  author       = {Helstad, Kristina and Rayner, Marilyn and van Vliet, Ton and Paulsson, Marie and Dejmek, Petr},
  issn         = {0268-005X},
  keyword      = {CaseinNanorheologyAdsorptionAFMSurface evolverModelling},
  language     = {eng},
  number       = {5-6},
  pages        = {726--738},
  publisher    = {Elsevier},
  series       = {Food Hydrocolloids},
  title        = {Liquid droplet-like behaviour of whole casein aggregates adsorbed on graphite studied by nanoindentation with AFM},
  url          = {http://dx.doi.org/10.1016/j.foodhyd.2006.10.006},
  volume       = {21},
  year         = {2007},
}