Flocculation and competitive adsorption in a mixed polymer system Relevance to casein-stabilized emulsions

Abstract

In a colloidal system containing two chemically similar adsorbable polymers, one a good steric stabilizer and the other not so good, the state of flocculation of the polymer-coated particles is determined by the competitive adsorption behaviour of the polymer. The key factors controlling the limits of stability can be expressed in terms of a simple model based on a system of sticky hard spheres. Evidence is presented to support the hypothesis that this approach may be useful in understanding the stability of oil-in-water emulsions containing a mixture of the milk proteins α_s1-casein and β-casein under conditions of moderate ionic strength.

References

1. D. H. Napper, Polymeric Stabilization of Colloidal Dispersions, Academic Press, London, 1993.
2. G. J. Fleer, M. A. Cohen Stuart, J. H. M. H. Scheutjens, T. Cosgrove and B. Vincent, Polymers at Interfaces, Chapman & Hall, London, 1993.
3. E. Dickinson and D. J. McClements, Advances in Food Colloids, Blackie, Glasgow, 1995.
4. E. Dickinson, in Food Colloids—Proteins, Lipids and Polysaccharides, ed. E. Dickinson and B. Bergenståhl, Royal Society of Chemistry, Cambridge, 1997, p. 107.
5. R. J. Baxter, in Physical Chemistry: An Advanced Treatise, ed. D. Henderson, Academic Press, New York, 1971, vol. IIIA.
6. Y. C. Chiew and E. D. Glandt, J. Phys. A, 1989, 22, 3969.
7. J. W. Perram and E. R. Smith, Proc. R. Soc. London, Series A, 1977, 353, 193.
8. E. Dickinson, J. Chem. Soc., Faraday Trans., 1992, 88, 3561.
9. R. O. Watts, D. Henderson and R. J. Baxter, Adv. Chem. Phys., 1971, 21, 421.
10. L. L. Muller, in Developments in Dairy Chemistry—1, ed. P. F. Fox, Applied Science, London, 1982, p. 315.
11. E. Dickinson, J. Dairy Res., 1989, 66, 865.
12. E. Dickinson, in Food Hydrocolloids; Structures, Properties and Functions, ed. K. Nishinari and E. Doi, Plenum, New York, 1993, p. 387.
13. E. Dickinson, R. H. Whyman and D. G. Dalgleish, in Food Emulsions and Foams, ed. E. Dickinson, Royal Society of Chemistry, London, 1987, p. 40.
14. D. G. Dalgleish, Trends Food Sci. Technol., 1997, 8, 1.
15. E. Dickinson, E. W. Robson and G. Stainsby, J. Chem. Soc., Faraday Trans. 1, 1983, 79, 2937.
16. E. Dickinson, S. E. Rolfe and D. G. Dalgleish, Food Hydrocoll., 1988, 2, 397.
17. H. E. Swaisgood, in ref. 10, p. 1.
18. A. S. Antipova, M. G. Semenova and E. Dickinson, unpublished work.
19. E. Dickinson, V. J. Pinfield, D. S. Horne and F. A. M. Leermakers, J. Chem. Soc., Faraday Trans., 1997, 93, 1785.
20. E. Dickinson, J. Chem. Soc., Faraday Trans., 1992, 88, 2973.
21. E. Dickinson and M. Golding, Food Hydrocoll., 1997, 11, 13.
22. E. Dickinson, M. Golding and M. J. W. Povey, J. Colloid Interface Sci., 1997, 185, 515.
23. E. Dickinson, D. S. Horne, V. J. Pinfield and F. A. M. Leermakers, J. Chem. Soc., Faraday Trans., 1997, 93, 425.
24. E. Dickinson, in Biopolymer Mixtures, ed. S. E. Harding, S. E. Hill and J. R. Mitchell, Nottingham University Press, Nottingham, 1995, p. 349.
25. R. J. Baxter, J. Chem. Phys., 1968, 49, 2770.
26. M. H. G. M. Penders and A. Vrij, Phys. Rev. A, 1992, 45, 1282.
27. M. G. H. Duits, R. P. May, A. Vrij and C. G. de Kruif, J. Chem. Phys., 1991, 94, 4521.
28. F. Pitré, C. Regnaut and M. P. Pileni, Langmuir, 1993, 9, 2855.
29. E. Dickinson, J. Chem. Soc., Faraday Trans., 1990, 86, 439.
30. E. Dickinson, J. Chem. Soc., Faraday Trans., 1995, 91, 4413.
31. E. Dickinson, An Introduction to Food Colloids, Oxford University Press, Oxford, 1992, ch. 7.
32. M. L. Green, D. G. Hobbs, S. V. Morant and V. A. Hill, J. Dairy Res., 1978, 45, 413.
33. C. G. de Kruif, in Food Colloids and Polymers: Stability and Mechanical Properties, ed. E. Dickinson and P. Walstra, Royal Society of Chemistry, Cambridge, 1993, p. 55.
34. C. G. de Kruif, M. A. M. Hoffmann, M. E. van Marle, P. J. J. M. van Mil, S. P. F. M. Roefs, M. Verheul and N. Zoon, Faraday Discuss., 1995, 101, 185.