Structure of Self-Assembled Globular Proteins - Food Colloids: Self-Assembly and Material Science - page 54

reduced, flexible linear aggregates are formed. With increasing ionic strength
and decreasing charge density, the degree of branching and flexibility increases,
which enhances the local density of the aggregates. On length-scales larger than
a few tens of nanometres, the aggregates have a self-similar structure charac-
terized by a fractal dimension close to 2.
When repulsive charge interactions are important, the interpenetrating ag-
gregates and gels are highly ordered and homogeneous on length-scales larger
than a few tens of nanometres. The degree of order decreases with decreasing
electrostatic interactions, which leads to an increase of the scattered light
intensity. Beyond a certain degree of heterogeneity, the systems become turbid
to the naked eye. The increase in the heterogeneity, and therefore in the
turbidity, is strong over a narrow range of salt concentrations and pH, but
the local arrangement of the proteins varies little. A clear distinction between
the so-called fine-stranded gels and particulate gels is not justified - the
difference simply represents a gradual transition from highly ordered to very
heterogeneous gels.
Acknowledgement
Dominique Durand is thanked for fruitful discussions and a critical reading of
the manuscript.
References
1. M. Rottereau, J.C. Gimel, T. Nicolai and D. Durand, Eur. Phys. J. E,
2004, 12, 133.
2. M.Y. Lin, H.M. Lindsay, D.A. Weitz, R. Klein, R.C. Ball and P. Meakin,
J. Phys., Condens. Matter, 1990, 2, 3093.
3. M. Kolb, R. Botet and R. Jullien, Phys. Rev. Lett., 1983, 51, 1123.
4. P. Meakin, Phys. Rev. Lett., 1983, 51, 1119.
5. D. Stauffer and A. Aharony, Introduction to Percolation Theory, Taylor &
Francis, London, 1992.
6. J.C. Gimel, T. Nicolai and D. Durand, Eur. Phys. J. E, 2001, 5, 415.
7. N.A.M. Verhaegh, D. Asnaghi and H.N.W. Lekkerkerker, Physica A,
1999, 264, 64.
8. E. Dickinson, J. Colloid Interface Sci., 2000, 225,2.
9. A.H. Clark, in Functional Properties of Food Macromolecules, 2nd edn,
S.E. Hill, D.A. Ledward and J.R. Mitchell (eds), Aspen, Gaithersburg,
MD, 1998, p. 77.
10. M.C. Bryant and D.J. McClements, Trends Food Sci. Technol., 1998, 9,
143.
11. C. Veerman, H. Ruis, L.M.C. Sagis and E. van der Linden, Biomacromole-
cules, 2002, 3, 869.
12. M. Weijers, L.M.C. Sagis, C. Veerman, B. Sperber and E. van der Linden,
Food Hydrocoll., 2002, 16, 269.