Scanning Electron Microscopy of Thermo-Sonicated Listeria Innocua Cells

  • D. Bermúdez
  • Gustavo V. Barbosa-Cánovas
Part of the Food Engineering series book series (FSES)

Listeria innocua cell structure was studied after conducting thermo-sonication treatments (24 kHz, 400 W, 120μm, 63°C) in order to establish a possible mechanism of cell inactivation. Raw and whole cow’s milk was used as the medium of treatment, and samples were analyzed after 10 min of thermo-sonication. Scanning electron microscopy (SEM) was used to identify possible injuries in cells after the treatment. The control sample showed complete integrity and non-disruption of the cell membrane, the characteristic rod shape of Listeria cells could be seen, and a smooth surface was clearly observable. After 10 min of sonication, the lethal effects of caviation were observed as the presence of small holes in the cell surface, perforations outside the cell wall, surface granules and disruption of the cell membrane. These preliminary effects are responsible for cell inactivation during the first minutes of treatment, and they increase the lethality of the sonication with longer treatment times.


Listeria Monocytogenes Ultrasonic Irradiation Early Stationary Phase Microbial Inactivation Longe Treatment Time 
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Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • D. Bermúdez
    • 1
  • Gustavo V. Barbosa-Cánovas
    • 1
  1. 1.Center for Nonthermal Processing of FoodWashington State UniversityPullmanUSA

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