Sterilization effect of pulsed light on various microorganisms
2002
Takeshita, K. (Prima Meat Packers Ltd., Tsuchiura, Ibaraki (Japan). Department of Basic Research) | Yamanaka, H. | Sameshima, T. | Fukunaga, S. | Isobe, S. | Arihara, K. | Itoh, M.
We investigated the killing effect of pulsed light against foodborne pathogens. After treatment with I flash of pulsed light at 0.7J/square cm (Pulse width 240 micro s), a reduction of 6 logs of vegetative bacteria and yeast, 3-5 logs of Bacillus spp. and Clostridium perfringens spores, and 2-4 logs of fungal spores was detected on agar plates. This new sterilizing method was found to be very effective, having high efficiency combined with a very short treatment time period. Moreover, a good correlation between total energy (Intensity of flash * flash time) and killing effect was observed. However, even if we increased the intensity of flash and flash time, a few of the microorganisms on the agar plate survived. It is reasoned that the killing effect of pulsed light depends on the surface condition where the microorganisms are present, and therefore in some cases we could not get the expected killing effect of pulsed light that is normally observed. There is no killing effect if wavelengths under 300nm were blocked, thereby indicating that the ultraviolet region is most important for the killing effect by pulsed light.
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