Relevant factors affecting microbial surface decontamination by pulsed light |
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Authors: | Levy Caroline Aubert Xavier Lacour Bernard Carlin Frédéric |
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Affiliation: | a CLARANOR S.A, Chemin de la Rollande, Agroparc, BP 21 531, F-84916 Avignon cedex 9, Franceb INRA, UMR408 Sécurité et qualité des produits d'origine végétale, F-84000 Avignon, Francec Université d'Avignon et des pays de Vaucluse, UMR 408 Sécurité et qualité des produits d'origine végétale, F-84000 Avignon, Franced Laboratoire de Physique des Gaz et des Plasmas, UMR 8578 CNRS & Université Paris-Sud, 91405 Orsay, France |
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Abstract: | Pulsed Light (PL) uses intense flashes of white light rich in ultraviolet (UV) light for decontamination. A log-reduction higher than 5 was obtained in one flash and at fluences lower than 1.8 J/cm2 on spores of a range of spore-forming bacteria, of vegetative cells of non-spore-forming bacteria and on yeasts spread on agar media. Vegetative cells were more sensitive than spores. The inactivation by PL of Bacillus subtilis, B. atrophaeus, B. cereus, Geobacillus stearothermophilus, and Aspergillus niger spores sprayed on polystyrene was similar. The inactivation by PL of B. subtilis and A. niger spores sprayed on glass was slightly lower than on polystyrene. No alteration of the spore structures was detected by scanning electron microscopy for both PL treated B. subtilis and A. niger spores. The inactivation of spores of B. subtilis, B. atrophaeus, B. cereus and B. pumilus by PL or by continuous UV-C at identical fluences was not different, and was much higher by PL for A. niger spores. The increase in the input voltage of the lamps (which also increases the UV-C %) resulted in a higher inactivation. There was no correlation between the resistance to heat and the resistance to PL. The relative effect of UV-C radiations and light thermal energy on PL inactivation was discussed. |
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Keywords: | Pulsed light Spores Decontamination Surface B subtilis A niger |
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