The Milk Salts and Their Interaction with Casein


In all milks that have been examined in sufficient detail, it is apparent that the concentrations of calcium and phosphate are in excess, sometimes considerably in excess, of the solubility of solid calcium phosphate. Indeed, for a limited number of species there is direct evidence of the existence of such a phase in association with casein micelles and for cow’s milk the composition and structure of the colloidal calcium phosphate have been the subject of many experimental and some theoretical investigations. So important is the calcium phosphate for the integrity of the casein micelle, and hence for the behaviour of the casein in milk processing, that there is a need to concentrate on the interaction of the two rather than to follow historical precedent and consider the milk salts in isolation or treat the interaction with casein as an afterthought. In this chapter, the basic physical chemistry (thermodynamics, kinetics) of the milk salt-casein system is first considered but centred on a cluster model of the nature of the colloidal calcium phosphate. The chapter goes further, however, in arguing in favour of a particular point of view regarding one of the most important biological functions of casein, i.e. that the casein micelle is a particular solution to a wider problem in biology of controlling type I (cooperative) phase transitions using rheomorphic proteins. Caseins prevent pathological calcifications of the mammary gland and this function has shaped the nature of these proteins to a large degree.


Calcium Phosphate Casein Micelle Amorphous Calcium Phosphate Dicalcium Phosphate Octacalcium Phosphate 
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  1. Aoki, T., Yamada, N., Tornita, I., et al.,(1987) Caseins are cross-linked through their ester phosphate groups by colloidal calcium phosphate, Biochim. Biophys. Acta,911 238–43.Google Scholar
  2. Aoki, T., Umeda, T. and Kako, Y. (1990) Cleavage of the linkage between colloidal calcium phosphate and casein on heating milk at high temperature. J. Dairy Res., 57, 349–54.CrossRefGoogle Scholar
  3. Betts, F., Blumenthal, N.C. and Posner, A. (1981) Bone mineralization. J. Crystal Growth, 53, 63–73.CrossRefGoogle Scholar
  4. Boulet, M. and Marrier, J.R. (1960) Solubility of tricalcium citrate in solutions of variable ionic strength and milk ultrafiltrate, J Dairy Sci., 43, 155–64.Google Scholar
  5. Byler, D.M. and Susi, H. (1986) Examination of the structure of proteins by deconvolved FTIR spectra, Biopolymers, 25, 469–87.CrossRefGoogle Scholar
  6. Creamer, L.K., Richardson T. and Parry, D.A.D. (1981) Secondary structure of bovine a-and I3-casein in solution, Arch. Biochem. Biophys., 211, 689–96.CrossRefGoogle Scholar
  7. Davies, D.T. and Law, A.J.R. (1980) The content and composition of protein in creamery milks in south-west Scotland. J. Dairy Res., 47, 83–90.CrossRefGoogle Scholar
  8. Geerts, J.P., Bekhof, J.J. and Sheerjon, J.W. (1983) Determination of the calcium ion activities in milk with a selective ion electrode. A linear relationship between the logarithm of time and the recovery of the calcium ion activity after heating, Neth. Milk Dairy J., 37, 197–211.Google Scholar
  9. Graham, E.R.B., Malcolm, G.N. and McKenzie, H.A. (1984) On the isolation and conformation of bovine I3-casein A’. J. Biol. Macromol., 6, 155–61.CrossRefGoogle Scholar
  10. Haga, M., Yamauchi, K. and Aoyagi, S. (1983) Conformation and some properties of bovine as2-casein group proteins, Agric. Biol. Chem., 47, 1467–71.CrossRefGoogle Scholar
  11. Holt, C. (1982) Inorganic constituents of milk. III. The colloidal calcium phosphate of cow’s milk. J. Dairy Res., 49, 29–38.CrossRefGoogle Scholar
  12. Holt, C. (1985) The milk salts: their secretion, concentrations and physical chemistry, in Developments in Dairy Chemistry — 3. Lactose and Minor Constituents, ( P.F. Fox, ed.), Elsevier Applied Science Publishers, London, pp. 143–81.CrossRefGoogle Scholar
  13. Holt, C. (1995) Effect of heating and cooling on the milk salts and the interaction with casein, in Monograph 9501 Heat Induced Changes in Milk, (P.F. Fox, ed.), International Dairy Federation, Brussels, pp. 105–33.Google Scholar
  14. Holt, C. and Hukins, D.W.L. (1991) Structural analysis of the environment of calcium ions in crystalline and amorphous calcium phosphates by X-ray absorption spectroscopy and a hypothesis concerning the biological function of the casein micelle, Int. Dairy J., 1, 151–65.CrossRefGoogle Scholar
  15. Holt, C. and Jenness, R. (1984) Interrelationships of constituents and partition of salts in milk samples from eight species, Comp. Biochem. Physiol., 77A, 275–82.CrossRefGoogle Scholar
  16. Holt, C. and van Kemenade, M.J.J.M. (1989) Interaction of phosphoproteins with calcium phosphates, in Calcified Tissue, ( D.W.L. Hukins, ed.), Macmillan, London, pp. 175–213.Google Scholar
  17. Holt, C. and Sawyer, L. (1993) Caseins as rheomorphic proteins: interpretation of the primary and secondary structures of the as 1-, ß-and x-caseins, J. Chem. Soc. Faraday Trans., 89, 2683–92.CrossRefGoogle Scholar
  18. Holt, C., Dalgleish, D.G. and Jenness, R. (1981) Calculation of the ion equilibria in milk diffusate and comparison with experiment, Anal. Biochem., 113, 154–63.CrossRefGoogle Scholar
  19. Holt, C., Davies, D.T. and Law, A.J.R. (1986) The effects of colloidal calcium phosphate content and milk serum free calcium ion concentration on the dissociation of bovine casein micelles. J. Dairy Res., 53, 557–72.CrossRefGoogle Scholar
  20. Holt, C., van Kemenade, M.J.J.M., Nelson, L.S. Jr., et al. (1989) Amorphous calcium phosphate precipitated at pH 6.5 and 6.0, Mater. Res. Bull., 23, 55–62.CrossRefGoogle Scholar
  21. Holt, C., Wahlgren, N.M. and Drakenberg, T. (1996) Ability of a (3-casein phosphopeptide to modulate the precipitation of calcium phosphate by forming amorphous dicalcium phosphate nanoclusters, Biochem. J., 314, 1035–9.Google Scholar
  22. Knoop, A-M., Knoop, E. and Wiechen, A. (1979) Sub-structure of synthetic casein micelles. J. Dairy Res., 46, 347–50.CrossRefGoogle Scholar
  23. Lyster, R.L.J. (1981) Calculation by computer of individual concentrations in a simulated milk salt solution II. An extension to the previous model. J. Dairy Res., 48, 85–9.CrossRefGoogle Scholar
  24. Lyster, R.L.J., Mann, S., Parker, S.B. and Williams, R.J.P. (1984) Nature of micellar calcium phosphate in cow’s milk as studied by high resolution electron microscopy, Biochim. Biophys. Acta, 801, 315–17.CrossRefGoogle Scholar
  25. McGann, T.C.A., Buchheim, W., Kearney, R.D. and Richardson, T. (1983a) Composition and ultrastructure of calcium phosphate-citrate complexes in bovine milk system, Biochim. Biophys. Acta, 760, 415–20.CrossRefGoogle Scholar
  26. McGann, T.C.A., Kearney, R.D., Buchheim, W., et al. (1983b) Amorphous calcium phosphate in casein micelles of bovine milk, Calcif. Tissue Int., 35, 821–3.CrossRefGoogle Scholar
  27. Mercier, J.-C., Vilotte, J.L. and Provot, C. (1990) Structure and function of milk protein genes, in Genome Analysis in Domestic Animals, ( H. Gelderman and F.J. Ellendorf, eds.), Verlagsgesellschaft mbH, Weinheim, Germany, pp. 233–58.Google Scholar
  28. Nancollas, G.H. (1981) Biological Mineralization and Demineralization, Springer Verlag, Berlin.Google Scholar
  29. Nielson, A.E. (1981) Theory of electrolyte crystal growth, Pure Applied Chem., 53, 2025–39.CrossRefGoogle Scholar
  30. Ono, T., Ohotawa, T. and Takagi, Y. (1994) Complexes of casein phosphopeptide and calcium phosphate prepared from casein micelles by tryptic digestion, Biosci. Biotechnol. Biochem., 58, 1376–80CrossRefGoogle Scholar
  31. Pierre, A., Brulé, G. and Fauquant, J. (1983) Etude de la mobilité du calcium dans le lait à l’aide du calcium 45, Lait, 63, 473–89.CrossRefGoogle Scholar
  32. Pouliot, Y., Boulet, M. and Paquin, P. (1989a) An experimental technique for the study of milk salt balance. J. Dairy Sci., 72, 36–40.CrossRefGoogle Scholar
  33. Pouliot, Y., Boulet, M. and Paquin, P. (1989b) Observations on the heat-induced salt balance changes in milk. I. Effect of heating time between 4 and 90°C. J. Dairy Res., 56, 185–92.CrossRefGoogle Scholar
  34. Pouliot, Y., Boulet, M. and Paquin, P. (1989c) Observations on the heat-induced salt balance changes in milk. II. Reversibility on cooling. J. Dairy Res., 56, 193–9.CrossRefGoogle Scholar
  35. Pyne, G.T. (1962) Reviews of the progress of dairy science. Section C. Dairy chemistry. Some aspects of the physical chemistry of the salts of milk. J. Dairy Res., 29, 101–30.CrossRefGoogle Scholar
  36. Rollema, H.S., Brinkhuis, J.A. and Vreeman, H.J. (1988) ‘H-NMR studies of bovine x-casein and casein micelles, Neth. Milk Dairy J., 42, 233–48.Google Scholar
  37. van Dijk, H.J.M. (1991) The properties of casein micelles. 4. The effect of the addition of NaC1, MgC12, or NaOH on the partition of Ca, Mg and PO4 in cows’ milk, Neth. Milk Dairy J., 45, 241–51.Google Scholar
  38. van Kemenade, M.J.J.M. (1988) Influence of casein on precipitation of calcium phosphates, PhD Thesis, University of Utrecht.Google Scholar
  39. van Kemenade, M.J.J.M. and de Bruyn, P.L. (1980a) The influence of casein on the kinetics of hydroxyapatite precipitation. J. Colloid Interf Sci., 129, 1–14.CrossRefGoogle Scholar
  40. van Kemenade, M.J.J.M. and de Bruyn, P.L. (1989b) The influence of casein on the precipitation of brushite and octacalcium phosphate, Colloids, Surf, 36, 359–68.Google Scholar
  41. Wahlgren, M., Dejmek, P. and Drakenberg, T. (1990) A 43Ca and 31P NMR study of the calcium and phosphate equilibria in heated milk solutions. J. Dairy Res., 57, 355–64.CrossRefGoogle Scholar
  42. Wahlgren, M., Dejmek, P. and Drakenberg, T. (1993) Binding of Cat+ and Mgt+ to 0-casein Al: a multinuclear magnetic resonance study. J. Dairy Res., 60, 6578.CrossRefGoogle Scholar
  43. White, J.C.D. and Davies, D.T. (1958) The relation between the chemical composition of milk and the stability of the reseinate complex. I. General introduction, description of samples, methods and chemical composition of samples, J. Dairy Res., 25, 236–55.CrossRefGoogle Scholar
  44. Yamauchi, K. and Yoneda, Y. (1977) Effect of some treatments of milk on the exchangeability of colloidal calcium in milk with soluble calcium, Agric. Biol. Chem., 41, 2395–9.CrossRefGoogle Scholar
  45. Yamauchi, K., Yoneda, Y., Koga, Y. and Tsugo, T. (1969) Exchangeability of colloidal calcium in milk with soluble calcium, Agric. Biol. Chem., 33, 907–14.CrossRefGoogle Scholar

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© Springer Science+Business Media Dordrecht 1997

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  • C. Holt

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