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Thermal inactivation of γ-glutamyltranspeptidase and Enterococcus faecium in milk-based systems

Published online by Cambridge University Press:  01 June 2009

Shailam S. Patel  and
R. Andrew Wilbey
Shailam S. Patel
Affiliation:
Department of Food Science, and Technology, University of Reading, Reading RG6 2AP, UK
R. Andrew Wilbey
Affiliation:
Department of Food Science, and Technology, University of Reading, Reading RG6 2AP, UK
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Summary

Untreated whole milk, skim milk, sweetened milks, sweetened and unsweetened creams and ice-cream mixes were preincubated with a culture of Enterococcus faecium, then subjected to heat treatment in a pilot-scale plate heat exchanger using a hold of 15 s at 76°C. The liquids were examined for γ-glutamyltranspeptidase (GGTP) activity and total streptococcal count before and after heat treatment and the results plotted against water activity (aw). There was a good correlation between reduction in GGTP activity, destruction of streptococci and aw, demonstrating the potential of the enzymic assay for assessing the severity of HTST heat treatments above the minimum for pasteurization.

Type
Original Articles
Information
Journal of Dairy Research , Volume 61 , Issue 2 , May 1994 , pp. 263 - 270
Copyright
Copyright © Proprietors of Journal of Dairy Research 1994

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