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Enhanced inactivation of bacterial lipases and proteinases in whole milk by a modified ultra high temperature treatment

Published online by Cambridge University Press:  01 June 2009

Anthony R. Bucky
Affiliation:
Department of Microbiology, University of Leeds, Leeds LS2 9JT, UK
Patrick R. Hayes
Affiliation:
Department of Microbiology, University of Leeds, Leeds LS2 9JT, UK
David S. Robinson
Affiliation:
Procter Department of Food Science, University of Leeds, Leeds LS2 9JT, UK

Summary

Cultures of Pseudomonas spp. strains P10, P12 and P15 grown in whole milk which contained ∼ 1 × 108 viable bacteria ml−1 demonstrated near linear increases in the concentration of short-chain free fatty acids and trichloroacetic acid soluble free amino groups at 20 °C, following either ultra high temperature (UHT) treatment (140 °C for 5 s) or dual heat treatments (140 °C followed by either 57, 60 or 65 °C). The dual heat treatments reduced the rates of lipolysis and proteolysis compared to the UHT treatment by up to 25-fold. The dual heat treatment utilizing 60 °C for 5 min also effectively limited both lipase and proteinase activities in raw milk culture samples which had contained either 6 × 106, 5 × 107 or 1 × 108 viable bacteria ml−1. In this system enzyme activities were reduced by up to 10-fold following dual heat treatment compared to UHT treatment alone.

Type
Original articles
Copyright
Copyright © Proprietors of Journal of Dairy Research 1988

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References

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