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Assay of proteinases of psychrotrophic bacteria in milk using Hide Powder Azure and a simple procedure for clarification of milk

Published online by Cambridge University Press:  01 June 2009

Donald Stead
Donald Stead
Affiliation:
AFRC Institute of Food Research, Reading Laboratory (University of Reading), Shinfield, Reading RG2 9AT, UK
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Summary

The clarification of milk by addition of solutions of Triton X-100 and EDTA after digestion of added Hide Powder Azure (HPA) was found to provide a simple method of determining the extracellular proteinase activity of Gram-negative psychrotrophic bacteria in pasteurized whole milk. The light absorbance of the clarified HPA digestion product was measured directly, after a brief incubation period, and was stable to storage of samples in diffuse daylight for at least 2 d. Proteinase produced by growth in refrigerated whole milk of as few as 2·5 × 106 cfu ml−1 of Pseudomonas fluorescens AR11 was detected.

Type
Original Articles
Information
Journal of Dairy Research , Volume 54 , Issue 2 , May 1987 , pp. 295 - 302
Copyright
Copyright © Proprietors of Journal of Dairy Research 1987

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References

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