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Title: Inactivation of Escherichia coli in milk by high-hydrostatic-pressure treatment in combination with antimicrobial peptides
Authors: Garcia-Graells, C ×
Masschalck, Barbara
Michiels, Christiaan #
Issue Date: 1999
Series Title: Journal of food protection vol:62 issue:11 pages:1248-1254
Conference: date:Katholieke Univ Leuven, Food Microbiol Lab, B-3001 Heverlee, Belgium
Abstract: We studied the inactivation in milk of four Escherichia coli strains (MG1655 and three pressure-resistant mutants isolated from MG1655) by high hydrostatic pressure, alone or in combination with the natural antimicrobial peptides lysozyme and nisin and at different temperatures (10 to 50 degrees C). Compared with that of phosphate buffer, the complex physicochemical environment of milk exerted a strong protective effect on E. coli MG1655 against high-hydrostatic-pressure inactivation, reducing inactivation from 7 logs at 400 MPa to only 3 logs at 700 MPa in 15 min at 20 degrees C. An increase in lethality was achieved by addition of high concentrations of lysozyme (400 mu g/ml) and nisin (400 IU/ml) to the milk before pressure treatment. The additional reduction amounted maximally to 3 logs in skim milk at 550 MPa but was strain dependent and significantly reduced in 1.55% fat and whole milk. An increase of the process temperature to 50 degrees C also enhanced inactivation, particularly for the parental strain, but even in the presence of lysozyme and nisin, a 15-min treatment at 550 MPa and 50 degrees C in skim milk allowed decimal reductions of only 4.5 to 6.9 for the pressure-resistant mutants. A substantial improvement of inactivation efficiency at ambient temperature was achieved by application of consecutive, short pressure treatments interrupted by brief decompressions, interestingly, this pulsed-pressure treatment enhanced the sensitivity of the cells not only to high pressure but also to the action of lysozyme and nisin.
ISSN: 0362-028X
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Centre for Food and Microbial Technology
Molecular Genetics Section (-)
Administration Rectorial Services - miscellaneous
× corresponding author
# (joint) last author

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