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Influence of concentration of milk solids on the dissociation of micellar κ-casein on heating reconstituted milk at 120°C

Published online by Cambridge University Press:  01 June 2009

Harjinder Singh  and
Lawrence K. Creamer
Harjinder Singh
Affiliation:
New Zealand Dairy Research Institute, Private Bag, Palmerston North, New Zealand
Lawrence K. Creamer
Affiliation:
New Zealand Dairy Research Institute, Private Bag, Palmerston North, New Zealand
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Summary

Skim milks were prepared from skim milk powder at several concentrations between 10 and 25% total solids and portions were pH-adjusted to between pH 6·3 and 7·1 and heated at 120°C. After ultracentrifugation (88000 g for 90 min), the supernatants were analysed using gel electrophoresis to determine the concentrations of β-lactoglobulin, α-lactalbumin and κ-casein. The dissociation of κ-casein from the micelles was dependent on both the pH and the total solids content of milk before heating. Both higher pH (in the range 6·5–7·l) and higher concentration increased the extent of dissociation. A further series of samples were heated for 2–11 min at 120°C at pH 6·55. κ-Casein dissociation increased with concentration and with heating time. It was concluded that as the milk increased in concentration, the pH at which micellar κ-casein dissociated on heating was lowered.

Type
Original articles
Information
Journal of Dairy Research , Volume 58 , Issue 1 , February 1991 , pp. 99 - 105
Copyright
Copyright © Proprietors of Journal of Dairy Research 1991

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References

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