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The relationship between membrane permeabilization and loss of viability by pulsed electric fields (PEF) depending on the treatment intensity and the treatment media pH in two gram-positive (Lactobacillus plantarum, Listeria monocytogenes) and two gram-negative (Escherichia coli, Salmonella senftenberg 775W) bacterial species has been investigated. Loss of(More)
The relationship between membrane damage and loss of viability following pressure treatment was examined in Escherichia coli strains C9490, H1071, and NCTC 8003. These strains showed high, medium, and low resistance to pressure, respectively, in stationary phase but similar resistance to pressure in exponential phase. Loss of membrane integrity was measured(More)
The inactivation of Bacillus subtilis spores by ultrasonic treatments under static pressure (Mano-Sonication, MS) and a combined MS/heat treatment (Mano-Thermo-Sonication) was investigated. The sporicidal effect of MS treatments depended on static pressure, amplitude of ultrasonic waves and treatment temperature. At 70 degrees C, pressure increments up to(More)
In the present study the influence of various environmental and physiological factors on the heat resistance of Enterobacter sakazakii (Cronobacter) have been investigated. Our results demonstrated that the heat resistance of E. sakazakii depended on the strain studied, the growth conditions - phase and temperature - the characteristics of treatment medium(More)
The ability of Staphylococcus aureus to develop stress resistance responses was investigated. Exponential growth phase cells of S. aureus CECT 4459 were exposed to sublethal conditions (acid and alkaline pH, hydrogen peroxide, and heat) and then the acquisition of resistance to acid (pH 2.5), alkali (pH 12.0), hydrogen peroxide (50mM), and heat (58 degrees(More)
AIMS The aim was to evaluate (i) the resistance of Escherichia coli BJ4 to citral in a buffer system as a function of citral concentration, treatment medium pH, storage time and initial inoculum size, (ii) the role of the sigma factor RpoS on citral resistance of E. coli, (iii) the role of the cell envelope damage in the mechanism of microbial inactivation(More)
A specially designed resistometer was constructed, and the lethal effect on Yersinia enterocolitica of ultrasonic waves (UW) at different static pressures (manosonication [MS]) and of combined heat-UW under pressure treatments (manothermosonication [MTS]) was investigated. During MS treatments at 30 degrees C and 200 kPa, the increase in the amplitude of UW(More)
In the range of 4-20 degrees C, growth temperature did not influence the heat resistance at 54-66 degrees C for Yersinia enterocolitica at pH 7 in citrate phosphate buffer. However, when cells were grown at 37 degrees C. the D62 increased from 0.044 to 0.17 min. This increase was constant at all heating temperatures tested (z = 5.7-5.8). Growth temperature(More)
The influence of the growth temperature and the pH of the heating medium on the heat resistance at different temperatures of Salmonella typhimurium ATCC 13311 was studied and described mathematically. The shift of the growth temperature from 10 to 37 degrees C increased heat resistance of S. typhimurium fourfold. The pH of the heating medium at which heat(More)