The combined effect of nisin, moderate heating and high hydrostatic pressure on the inactivation of Bacillus sporothermodurans spores

Authors

  • C. Aouadhi,

    Corresponding author
    1. LUNAM Université, Oniris, GEPEA, Nantes, France
    2. CNRS, Nantes, France
    3. Laboratory of Animal Resources and Food, National Institute of Agronomy, University Carthage, Tunis, Tunisia
    • Laboratory of Epidemiology and Veterinary Microbiology, Bacteriology and Biotechnology Development Groups, Pasteur Institute of Tunisia (IPT), University Manar, Tunis, Tunisia
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  • H. Simonin,

    1. LUNAM Université, Oniris, GEPEA, Nantes, France
    2. CNRS, Nantes, France
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  • S. Mejri,

    1. Laboratory of Animal Resources and Food, National Institute of Agronomy, University Carthage, Tunis, Tunisia
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  • A. Maaroufi

    1. Laboratory of Epidemiology and Veterinary Microbiology, Bacteriology and Biotechnology Development Groups, Pasteur Institute of Tunisia (IPT), University Manar, Tunis, Tunisia
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Correspondence

Chedia Aouadhi, Laboratoire d'Epidémiologie et Microbiologie Vétérinaire, Groupes de Bactériologie et Développement Biotechnologique. Institut Pasteur de Tunis, BP 74, 13 place Pasteur, Belvédère, 1002 Tunis, Tunisia. E-mail: chediaaouadhi@yahoo.fr

Abstract

Aims

To investigate the combined effect of hydrostatic pressure (HP), moderate temperature and nisin on the inactivation of Bacillus sporothermodurans spores which are known to be contaminant of dairy products and to be extremely heat-resistant.

Methods and Results

A central composite experimental design with three factors, using response surface methodology, was used. By analysing the response surfaces and their corresponding contour plots, an interesting interaction with the three factors was observed. The inactivation observed was shown to be well fitted with values predicted by the quadratic equation, since the adjusted determination coefficient (Radj2) was 0·979. The optimum process parameters for a 5-log spores ml−1 reduction of B. sporothermodurans spores were obtained, 472 MPa/53°C for 5 min in presence of 121 UI ml−1 of nisin.

Conclusion

Nisin and temperature treatments improve the effectiveness of pressure in the inactivation of highly heat-resistant spores of B. sporothermodurans.

Significance and Impact of the Study

This study shows the potential of using high HP for a short time (5 min) in combination with moderate temperature and nisin to inactivate B. sporothermodurans spores in milk. Such treatments could be applied by the dairy industry to ensure the commercial sterility of UHT milk.

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