Applications for UV light in the food industry

Heraeus Amba Australia Pty Ltd
Tuesday, 06 November, 2012

UV light is used for a large variety of applications in the food industry. With high-performance UV light sources and equipment, water, air and surfaces can be reliably disinfected, cleaned and treated. The use of chemicals can be reduced or even avoided in an economical and environmentally friendly way.

UV light has been shown to be effective on most bacterial microorganisms, as well as viruses and moulds. Ultraviolet light at wavelengths of 254 nm destroys the DNA of all microorganisms so viruses, bacteria, yeasts and fungi are disabled in seconds.

For a whole series of microorganisms, the lethal dose of UV radiation is known: this is the dose after which the cells can no longer maintain their metabolism and can also no longer multiply. Because of the cell structure, the lethal dose for different pathogens varies. Consequently, bacteria such as Salmonella, Listeria and E. coli, which have a comparatively thin cell wall and can thus only slightly block the UV radiation, are extremely vulnerable and are very easily destroyed. On the other hand, mould spores protect themselves against UV radiation with a thick cell wall, which can even be pigmented. To kill these, a UV dose which is 10 to 100 times higher than that required for bacteria is needed.

On surfaces such as conveyor belts, particularly in the meat and meat processing areas, UV light can be used to provide continuous decontamination in the form of a module designed to expose the belt to UV as it passes. The module is completely watertight and can be incorporated into CIP best practices. The intense germicidal action of UV light acts on microorganisms on the belt surface, rendering them inactive. This treatment can reduce the number of complete washdowns required during processing, thereby saving resources such as water and energy costs.

In the dairy industry, UV disinfection is used especially for the packaging of fresh milk products, such as yoghurt, cream cheese and dips, which are kept in the cool chain, in order to improve shelf life. This means that the dairy processor has significantly fewer returns of spoiled product.

In baking, mould spores in the processing environment contribute to significant wastage, reducing shelf life and costing money. In most cases, the installation of a UV tunnel over the production line can provide an effective solution.

In addition, pre-packaged fresh vegetables and fruits can be treated and the packaging exposed to UV light to decrease the incidence of spoiling.

An assessment of the possible sources of mould spores in the processing environment usually indicates a build-up of material in the air supply. In order to treat the incoming air, a simple, economical and effective step is the installation of UV light in the air duct. Installing UV light at the cooling coils keeps the coil fins free from ‘bio-film’ build-up, which is the breeding ground for contaminants that are then circulated through the processing environment. Not only can UV light in the ducting contribute to a reduction in spoilage, the HVAC system needs manual cleaning less often and can be shown to work more efficiently, thereby saving on maintenance and energy costs.

UV light at 185 nm facilitates the creation of ozone, which is used to destroy odours and grease deposits associated with cooking and food processing. In the meat processing and rendering industry, ozone lamps can be used to effectively control odours that would otherwise disperse into the surrounding area causing concern to local residents.

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