Effect of high pressure and sub-zero temperature on some gram-negative bacteria
Malinowska-Panczyk, E. | Kolodziejska, I. | Dunajski, E. | Rompa, M. | Cwalina, S.(Gdansk Technical University (Poland). Dept. of Food Chemistry and Technology)
The objective of the investigations was to determine the viability of selected gram-negative bacteria exposed to high pressure and sub-zero temperature, in the range of 59-193 MPa and -5 - -20 deg C, respectively, without the freezing of water. After pressurization for 24 h, at 193 MPa and -20 deg C, no living cells of gram-negative bacteria T. thermophilus, P. fluorescens and E. coli of the initial population number of 10E8 CFU/mL were detected. After pressure treatment for a shorter time than 24 h, differences in sensitivity appeared between these bacteria. The most resistant was the tested strain of E. coli. Reduction in the population of E. coli was only about 3.5 log cycles after pressurization for 30 min at -20 deg C, while T. thermophilus and P. fluorescens were completely inactivated under these conditions
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