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The free and masked sulphydryl groups of heated milk and milk powder and a new method for their determination

Published online by Cambridge University Press:  01 June 2009

R. L. J. Lyster
Affiliation:
National institute for Research in Dairying, Shinfield, Reading

Summary

A new method is described for the determination of the free and masked sulphydryl (-SH) groups in heated milk and milk products. The procedure is based on the use of the specific -SH reagent p-chloromercuribenzoate, and utilizes another specific -SH reagent, 5,5' -dithiobis(2-nitrobenzoate), as an indicator producing yellow colours which are matched with the aid of standard glasses in the Lovibond Comparator.

The method was applied to heated skim-milks and a series of commercially prepared milk powders. Measurements were made in particular of the -SH content of UHT-treated milk. The changes in the -SH content of such milks on storage were studied; these changes could not be explained by a reversal of the denaturation of the whey proteins, although evidence was obtained that small amounts of heatdenatured whey protein can revert to the native state.

Type
Original Articles
Copyright
Copyright © Proprietors of Journal of Dairy Research 1964

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References

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