Abstract
THE component of the casein complex which, according to Waugh and Von Hippel1, is responsible for the colloid chemical stability of the casein micelles in milk is k-casein. The same authors have also given its preparation, as follows. The casein in skim milk is precipitated by addition of calcium, and by subsequent removal of calcium from the precipitate a solution of the so-called ‘first cycle casein’ is obtained. This first cycle casein contains β-casein and the α/k-complex. Reprecipitating first cycle casein with 0.25 M calcium chloride at 37° C. results in the splitting of the α/k-complex and hence in the chemical instability of the casein micelles in the colloid. The precipitate was named ‘second cycle casein’, and it no longer contains the protective k-casein in stabilizing quantities. The latter can be isolated from the remaining supernatant of second cycle casein. In its physico-chemical properties, such as electrophoretic mobility, diffusion and ultra-centrifugation characteristics, k-casein was shown to resemble α-casein closely.
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References
Waugh, D. F., and von Hippel, P. H., J. Amer. Chem. Soc., 78, 4576 (1956).
Nitschmann, Hs., and Lehmann, W., Experientia, 3, 153 (1947).
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PAYENS, T. First and Second Cycle Casein in Milk. Nature 181, 114 (1958). https://doi.org/10.1038/181114a0
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DOI: https://doi.org/10.1038/181114a0
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