Cross-Contamination and its Role in Food Poisoning Outbreaks Cross-contamination is one of the most major causes of food poisoning (Food Standards Agency, 2014). It is defined as ‘the process by which a substance that is harmful or dirty spreads from one area to another’ (Cambridge Online Dictionary, 2014) .There are 3 different types of contamination in the food industry; microbial contamination, physical contamination and chemical contamination, with microbial contamination being a more frequent cause of food poisoning and rising, with the amount of products contaminated having risen 91% between 2006 and 2011 (Department for Environment, Food and Rural Affairs , 2012) . A variety of things can cause microbial cross-contamination, but the most common causes are through vehicles or vectors carrying harmful bacteria (pathogens) from a source to the food. The source or reservoir is where the contamination originates from, for example, humans, raw food, rodents, dust and soil. In the context of cross-contamination, a vehicle is a substance, object or living thing that moves the contaminant away from its source to the food. The vehicle could either be stationary or a mobile vehicle. A vector is an organism, usually a bird or an insect, that transmits a pathogen from one place to another. The aim for a food manufacturer is to make a commercially sterile, not completely sterile. The definition for a commercially sterile product is “Commercial sterility of food means the conditions achieved by application of heat which renders such food free from microorganisms capable of growing in the food at temperatures at which the food is likely to be held during distribution and storage.” (Food and Agriculture Organisation, 2007). The reason for this is that the severe thermal treatment needed to make a product completely sterile would severely reduce the sensory quality and nutritional value of the product, as well as increasing the energy consumption to reach higher heats. There are various reasons as to why cross-contamination happens and is a major cause of food poisoning, for example, poor hand washing techniques, confusion of terminology by staff, equipment design and colour coded equipment which people do not adhere to. It is also very difficult to track down the causes of an outbreak, so it may take a while to take the relevant measures to stop the outbreak and sometimes the wrong thing is blamed, for example, in 2011, Spanish fruit and vegetables were blamed for an E. coli outbreak across Europe, killing 22 people. However, it was later discovered that German bean sprouts were the likely cause (BBC News, 2011). The mistake cost the Spanish fruit and vegetable industry £200m per week, proving how economically important it is to get the causes right (BBC News, 2011). In many food poisoning cases, a sequence of events contributes to an outbreak, rather than just one activity alone. This is called the microbial chain and makes it even harder to discover the true cause of an outbreak. An example of a microbial chain is; cooked ham comes into a store and is sliced. This ham has come from the supplier contaminated so has now contaminated the slicer used. The slicer is not washed and other meats, for example, more cooked ham or cooked beef, is sliced on it. This then causes the other meats to become contaminated, making it difficult to find the meat that originally caused the problem. The cooked meat that has been contaminated is ready to eat, so therefore is a high risk product as no further treatment will be done to kill pathogens, meaning it is very likely that a case of food poisoning would come from this microbial chain if the pathogen was harmful enough.
A wide range of things can act as vehicles for microbes, for example, hands, clothes, cleaning cloths and pests can all act as mobile vehicles, and food-contact surfaces, food itself and hand-contact surfaces, such as door handles, fridge door and taps, can all act as...
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