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The effects of growth temperature and growth phase on the inactivation of Listeria monocytogenes in whole milk subject to high pressure processing.
Int J Food Microbiol. 2007 Apr 10; 115(2):220-6.IJ

Abstract

The aim of this study was to explore the effect of a wide range of growth temperatures, growth phases and plating media on the inactivation of Listeria monocytogenes by high pressure processing (HPP). In part one, L. monocytogenes was grown to mid-stationary phase at 4, 15, 25, 35 or 43 degrees C, inoculated into whole UHT milk at approximately 10(7) CFU/ml and high pressure processed at 400 MPa at room temperature (20-25 degrees C). Afterward, the HPP milk was plated on Tryptic Soy Yeast Extract Agar (TSYEA) and Modified Oxford Agar (MOX) to determine the degree of injury. For part two, cells were grown to mid-exponential, late-exponential or mid-stationary phase at 15 or 43 degrees C and processed in the same way. Time to reach a 5-log reduction was determined and data were analysed by ANOVA. The results from part one showed that both growth temperature and plating medium had a significant effect (P < 0.001) on the inactivation of stationary phase L. monocytogenes by HPP. Tukey's pairwise comparisons revealed that the effects of all temperatures, except 35 and 43 degrees C, were significantly different (P < 0.05). Cells grown at 15 degrees C were most sensitive to HPP, followed by cells grown at 4, 25 or 35 degrees C, with cells grown at 43 degrees C appearing to be the most resistant. Inactivation of cells grown at 4, 15 or 25 degrees C followed first order kinetics, whereas cells grown at 35 or 43 degrees C displayed non-linear inactivation kinetics due to tailing. In part two, both growth phase and plating medium had significant effects on the inactivation (P < or = 0.001) of L. monocytogenes by HPP. Cells grown at 15 degrees C to mid-stationary phase were the most pressure-resistant when tested on both media, and were significantly more resistant (P < 0.05) than cells grown at the same temperature to the other two phases of growth. There was no significant difference between mid- and late-exponential phase cells grown at 15 degrees C. When cells were grown at 43 degrees C, mid-exponential phase cells were significantly more sensitive (P < 0.05) than either late-exponential or mid-stationary phase cells, with no difference between late-exponential or mid-stationary phase cells. It was postulated that membrane composition, stationary phase proteins and/or stress proteins may affect pressure resistance.

Authors+Show Affiliations

Hayman MM
Department of Food Science, The Pennsylvania State University, 202 Food Science Building, University Park, PA 16802, USA. mmh236@psu.edu
Anantheswaran RC
No affiliation info available
Knabel SJ
No affiliation info available

MeSH

Analysis of VarianceAnimalsColony Count, MicrobialConsumer Product SafetyFood ContaminationFood MicrobiologyHumansHydrostatic PressureKineticsListeria monocytogenesMilkTemperature

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

17173999

Citation

Hayman, Melinda M., et al. "The Effects of Growth Temperature and Growth Phase On the Inactivation of Listeria Monocytogenes in Whole Milk Subject to High Pressure Processing." International Journal of Food Microbiology, vol. 115, no. 2, 2007, pp. 220-6.
Hayman MM, Anantheswaran RC, Knabel SJ. The effects of growth temperature and growth phase on the inactivation of Listeria monocytogenes in whole milk subject to high pressure processing. Int J Food Microbiol. 2007;115(2):220-6.
Hayman, M. M., Anantheswaran, R. C., & Knabel, S. J. (2007). The effects of growth temperature and growth phase on the inactivation of Listeria monocytogenes in whole milk subject to high pressure processing. International Journal of Food Microbiology, 115(2), 220-6.
Hayman MM, Anantheswaran RC, Knabel SJ. The Effects of Growth Temperature and Growth Phase On the Inactivation of Listeria Monocytogenes in Whole Milk Subject to High Pressure Processing. Int J Food Microbiol. 2007 Apr 10;115(2):220-6. PubMed PMID: 17173999.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The effects of growth temperature and growth phase on the inactivation of Listeria monocytogenes in whole milk subject to high pressure processing. AU - Hayman,Melinda M, AU - Anantheswaran,Ramaswamy C, AU - Knabel,Stephen J, Y1 - 2006/12/14/ PY - 2006/05/15/received PY - 2006/07/25/revised PY - 2006/10/26/accepted PY - 2006/12/19/pubmed PY - 2007/5/15/medline PY - 2006/12/19/entrez SP - 220 EP - 6 JF - International journal of food microbiology JO - Int J Food Microbiol VL - 115 IS - 2 N2 - The aim of this study was to explore the effect of a wide range of growth temperatures, growth phases and plating media on the inactivation of Listeria monocytogenes by high pressure processing (HPP). In part one, L. monocytogenes was grown to mid-stationary phase at 4, 15, 25, 35 or 43 degrees C, inoculated into whole UHT milk at approximately 10(7) CFU/ml and high pressure processed at 400 MPa at room temperature (20-25 degrees C). Afterward, the HPP milk was plated on Tryptic Soy Yeast Extract Agar (TSYEA) and Modified Oxford Agar (MOX) to determine the degree of injury. For part two, cells were grown to mid-exponential, late-exponential or mid-stationary phase at 15 or 43 degrees C and processed in the same way. Time to reach a 5-log reduction was determined and data were analysed by ANOVA. The results from part one showed that both growth temperature and plating medium had a significant effect (P < 0.001) on the inactivation of stationary phase L. monocytogenes by HPP. Tukey's pairwise comparisons revealed that the effects of all temperatures, except 35 and 43 degrees C, were significantly different (P < 0.05). Cells grown at 15 degrees C were most sensitive to HPP, followed by cells grown at 4, 25 or 35 degrees C, with cells grown at 43 degrees C appearing to be the most resistant. Inactivation of cells grown at 4, 15 or 25 degrees C followed first order kinetics, whereas cells grown at 35 or 43 degrees C displayed non-linear inactivation kinetics due to tailing. In part two, both growth phase and plating medium had significant effects on the inactivation (P < or = 0.001) of L. monocytogenes by HPP. Cells grown at 15 degrees C to mid-stationary phase were the most pressure-resistant when tested on both media, and were significantly more resistant (P < 0.05) than cells grown at the same temperature to the other two phases of growth. There was no significant difference between mid- and late-exponential phase cells grown at 15 degrees C. When cells were grown at 43 degrees C, mid-exponential phase cells were significantly more sensitive (P < 0.05) than either late-exponential or mid-stationary phase cells, with no difference between late-exponential or mid-stationary phase cells. It was postulated that membrane composition, stationary phase proteins and/or stress proteins may affect pressure resistance. SN - 0168-1605 UR - https://www.unboundmedicine.com/medline/citation/17173999/The_effects_of_growth_temperature_and_growth_phase_on_the_inactivation_of_Listeria_monocytogenes_in_whole_milk_subject_to_high_pressure_processing_ DB - PRIME DP - Unbound Medicine ER -