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6 Cards in this Set
- Front
- Back
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Describe how broad spectrum light pulses are achieved. |
Discharging a high voltage capacitor bank through xenon flash tubes - delivering a spectrum 90,000 times more intense than sunlight at sea level |
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What is the wavelength range of broad spectrum pulsed light? |
200-1000nm UV to infrared |
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What types of light are used in pulsed light applications? |
For surfaces, packaging materials, air, water or salt solutions: - UV rich light is used - At least 30% of light energy is at wavelengths < 300nm (263.7nm = lethal wavelength) For foods: - UV portion of light is filtered out - UV can affect the quality and flavour of some foods |
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Describe the mechanism of inactivation by pulsed light. |
Primarily due to interactions with DNA as described with UV radiation Inactivation can also occur due to the rupture/lysing of the cell wall as temperature increases in the superficial surface layers of the cells When UV filtered out - only visible and infrared spectrum left - mechanism of inactivation is primarily photo-thermal |
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What are the applications of pulsed light in the food industry |
Mainly in sterilising or reducing the microbial population on the surface of: - Packaging materials - Transparent pharmaceutical products - Process surfaces
Can be applied for the sterilisation of spores and vegetative cells in liquids: - In containers - Flowing through treatment chambers |
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What are the three critical processing factors for the use of broad spectrum pulsed light? |
1. Light characteristics: Spectrum 2. Packaging: Transparent (able to sterilise product) vs. opaque (not possible to sterilise product) 3. Food attributes: Type, transparency, colour, depth of fluid column |
