Hostname: page-component-7c8c6479df-r7xzm Total loading time: 0 Render date: 2024-03-28T10:16:54.977Z Has data issue: false hasContentIssue false

Contribution of the lactoperoxidase system to the keeping quality of pasteurized milk

Published online by Cambridge University Press:  01 February 1999

NICHOLETTE E. BARRETT
Affiliation:
Department of Food Science and Technology, The University of Reading, PO Box 226, Reading RG6 6AP, UK
ALISTAIR S. GRANDISON
Affiliation:
Department of Food Science and Technology, The University of Reading, PO Box 226, Reading RG6 6AP, UK
MICHAEL J. LEWIS
Affiliation:
Department of Food Science and Technology, The University of Reading, PO Box 226, Reading RG6 6AP, UK

Abstract

The lactoperoxidase system is a naturally occurring antimicrobial system found in milk, with lactoperoxidase, thiocyanate and hydrogen peroxide as its components. The keeping quality of milk pasteurized at 72°C for 15 s was found to be better than that of milk heated at 80°C for 15 s. This agrees with previous findings and is usually attributed to heat shocking of spores. However, complete deactivation of lactoperoxidase occurred at 80°C–15 s, whereas at 72°C–15 s residual lactoperoxidase activity was ∼70%, which may provide an alternative explanation. Higher levels of hypothiocyanite (the major antimicrobial agent produced by the lactoperoxidase system) were also detected in milk processed at 72 than at 80°C, which supports the theory that the lactoperoxidase system has a role in the keeping quality of pasteurized milk. Of all the methods evaluated, titratable acidity and alcohol stability gave the most consistent estimates of keeping quality, while dissolved oxygen was a good indication of the onset of spoilage. Lactoperoxidase activity decreased with temperature more rapidly between 70 and 80°C than is usual for an enzyme over a 10 deg C range.

Type
Research Article
Copyright
Proprietors of Journal of Dairy Research 1999

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)