Growth of Listeria monocytogenes and Yersinia enterocolitica colonies under modified atmospheres at 4 and 8 °C using a model food system

• Published in: Journal of applied microbiology Vol. 88; no. 1; pp. 38 - 43
• Main Authors: Harrison, W. A., Peters, A. C., Fielding, L. M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01-01-2000; Blackwell Science; Oxford University Press
• Subjects: Biological and medical sciences; Food industries; Food microbiology; Fundamental and applied biological sciences. Psychology; Microorganism growth; Listeria monocytogenes; Foodstuff; Yersinia enterocolitica; Pathogenic; Food security; Food preservation; Packaging; Bacteria; Modified atmosphere; Refrigeration; Biological contamination; Enterobacteriaceae
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1046/j.1365-2672.2000.00848.x

W.A. HARRISON, A.C. PETERS and L.M. FIELDING.2000. The growth of Listeria monocytogenes and Yersinia enterocolitica colonies was studied on solid media at 4 and 8 °C under modified atmospheres (MAs) of 5% O2 : 10% CO2 : 85% N2 (MA1), 30% CO2 : 70% N2 (MA2) and air (control). Colony radius, determined using computer image analysis, allowed specific growth rates (μ) and the time taken to detect bacterial colonies to be estimated, after colonies became visible. At 4 °C both MAs decreased the growth rates of L. monocytogenes by 1·5‐ and 3·0‐fold under MA1 (μ = 0·02 h−1) and MA2 (μ = 0·01 h−1), respectively, as compared with the control (μ = 0·03 h−1). The time to detection of bacterial colonies was increased from 15 d (control) to 24 (MA1) and 29 d (MA2). At 8 °C MA2 decreased the growth rate by 1·5‐fold (μ = 0·04 h−1) as compared with the control (μ = 0·06 h−1) and detection of colonies increased from 7 (control) to 9 d (MA2). At 4 °C both MAs decreased the growth rates of Y. enterocolitica by 1·5‐ and 2·5‐fold under MA1 (μ = 0·03 h−1) and MA2 (μ = 0·02 h−1), respectively, as compared with the control (μ = 0·05 h−1). At 8 °C identical growth rates were obtained under MA1 and the control (μ = 0·07 h−1) whilst a decrease in the growth rate was obtained under MA2 (μ = 0·04 h−1). The detection of colonies varied from 6 (8 °C, aerobic) to 19 d (4 °C, MA2). Refrigerated modified atmosphere packaged foods should be maintained at 4 °C and below to ensure product safety.