Listeria Monocytogenes is found almost everywhere and can be readily isolated from most environments including soil, humans, animals, agricultural irrigation sources, decaying plant residue on equipment, bins and fresh-cut processing systems. The risk is highest in refrigerated and ready to eat foods because this bacteria is one of the few foodborne pathogens that is capable of multiplying in refrigerated temperatures. This widespread nature of the bacteria mandates a systematic approach to sanitation of high risk locations.
The fact that listeria is present in most environments makes it almost impossible to eliminate it completely from food processing environments. The reason for this is that it is continually being reintroduced into the processing areas by employees, incoming products and equipment.
Controlling this bacteria in any processing plant requires the overall reduction of these pathogens on surfaces on a regular basis. Preventing their growth and proliferation by managing the environment at every stage in the preparation or processing of that food item, is critical to ensure the safety of the product. Guidelines for the management of listeria can vary across industry sectors and the item being processed.
A product is most likely to become contaminated when it comes in contact with a contaminated surface. Common sites for this type of cross contamination include slicers, dicers, shredders, blenders, coolroom door handles and fans. Containers such as bins, tubs or baskets used for spin drying or storing a product before packing are also problem areas. Some items like maintenance tools, rotating blades, conveyor belts, gloves and aprons that may come in contact with a finished product should also be included in your cleaning checklist. Food processors and large food service operations should check racks for transporting the product prior to packing, trolleys, forklifts, assembly equipment responsible for handling the product, and the packaging material used is often overlooked but important to consider. Lastly, cleaning tools such as sponges or brushes may be considered ‘clean’, but may harbour more bacteria than other place in the plant.
Regular sampling of areas that are most attractive to these opportunistic bacteria such as drains, floors, walls and ceilings including any physical structure that is leaking condensate, should all be included in your regular testing. In some cases, even air samples may be required, the regularity of which is determined by the environment.
Any food business can mitigate the spread of listeriosis through the proper training of personnel. Ensuring that employees are aware of high risk areas throughout the food preparation or processing areas will create a greater awareness of potential contamination. The greatest risks are those seemingly insignificant practices that ultimately become catastrophic for any processing plant.
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offers practical solutions to both management and staff in hospitals, aged care facilities, restaurants, hotels and the food industry. We specialise in the development of useful tools to assist businesses in the areas of food safety, strategic planning, business management, risk and compliance training and business consultancy solutions. Call or email us today for any questions you may have on how to monitor Listeria within your food manufacturing or processing business.