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The effect of growth stage and growth temperature on high hydrostatic pressure inactivation of some psychrotrophic bacteria in milk.

Author(s) : MCCLEMENTS J. M. J., PATTERSON M. F., LINTON M.

Type of article: Article

Summary

The effect of high hydrostatic pressure on the survival of the psychrotrophic organisms Listeria monocytogenes, Bacillus cereus, and Pseudomonas fluorescens was investigated in ultrahigh-temperature milk. Variation in pressure resistance between two strains of each organism were studied. The effect of growth stage, growth temperature (8 and 30 °C) on pressure resistance, and sublethal pressure injury were investigated. Exponential-phase cells were significantly less resistant to pressure than stationary-phase cells for all of the three species studied (P <0.05). Growth temperature was found to have a significant effect. Exponential cells grown at 8 °C were more resistant than those grown at 30 °C but for stationary-phase cells the reverse was true. B. cereus and P. fluorescens. B. cereus spores were more resistant to pressure than vegetative cells. Pressure treatment at 400 MPa for 25 min at 30 °C gave a 0.45-log inactivation. Pressure treatment at 8 °C induced significantly less spore germination than at 30 °C. This study indicates the importance of the history of a bacterial culture prior to pressure treatment and that bacterial spores require more severe pressure treatments, probably in combination with other preservation techniques, to ensure inactivation.

Details

  • Original title: The effect of growth stage and growth temperature on high hydrostatic pressure inactivation of some psychrotrophic bacteria in milk.
  • Record ID : 2001-2798
  • Languages: English
  • Source: Journal of Food Protection - vol. 64 - n. 4
  • Publication date: 2001/04
  • Document available for consultation in the library of the IIR headquarters only.

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