HIGH PRESSURE DESTRUCTION KINETICS of INDIGENOUS MICROFLORA and ESCHERICHIA COLI IN RAW MILK AT TWO TEMPERATURES

Autor: Pramod K. Pandey, Hosahalli S. Ramaswamy, Edmund S. Idziak
Rok vydání: 2003
Předmět:
Zdroj: Journal of Food Process Engineering. 26:265-283
ISSN: 1745-4530
0145-8876
DOI: 10.1111/j.1745-4530.2003.tb00601.x
Popis: Raw milk with a high count of indigenous microflora, with and without inoculated Escherichia coli K-12 (ATCC-29055), was subjected to high pressure treatment (250-400 MPa) for various holding times (0-80 min) at two temperatures (3 and 21 C). From the microbial survivor data, an instantaneous pressure kill value (IPK) which represented the effect of a pressure pulse, and kinetic parameters (rate constant, D-value, z-value and activation volume) were evaluated based on pressure hold-time first order kinetics. Both IPK and D values were dependent on pressure level and temperature. Higher pressures, longer holding times and lower temperatures resulted in larger destruction of microorganisms, and E. coli was more pressure sensitive than indigenous microflora. Pressure dependency of kinetic parameters was well described by both pressure death time and Eyring-Magee models. At 3 and 21C, the z p values were 227 and 240 MPa and ΔV ? values were -2.32 and -2.34 (x 10 -5 m 3 mole -1 ), respectively, for indigenous microflora, and 179 and 205 MPa (z p ) and -2.95 and -2.75 (x 10 -5 m 3 mole -1 ) (ΔV ¬= ), respectively, for E. coli.
Databáze: OpenAIRE
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