Controlling the risk of unintentional allergen ingredients in food and drink products is important for moral, financial and legal reasons. Publicised cases of cross contamination hazards have resulted in enforcement action and prosecution.
Environmental Health Officers successfully obtained a prohibition order to prevent a restaurant in Birmingham from serving people with food allergies following hospitalisation of a customer1. An inspection of the premises found cross contamination risks in many areas and a general lack of knowledge about allergen ingredients in food products1.
Local authority councils do conduct test purchases to verify claims made by a food business in supplying products to customers with food allergies. A food safety officer ordered a peanut free meal curry, but analysis confirmed presence of peanut protein at a level to induce an allergic reaction. An inspection of the restaurant and takeaway identified potential risks for cross-contamination. The restaurant was prosecuted and fined £55002.
Sharing equipment between different allergenic ingredients and poor risk perception by food handlers can result in harm to customers. A tourist with a food allergy to all seafood suffered severe sickness after kitchen staff in Ibiza served her food with utensils used to cook mackerel and kitchen3.
Contamination can be defined as the presence or introduction of something harmful or objectionable.
Unintentional or undeclared presence of allergens in prepacked products may occur due to ineffective allergen management (e.g. cleaning or mispacking/mislabelling) and is the most common cause of product recalls in the UK. A study published by the Food Standards Agency in 2014 reported gluten (3.3%) and milk (2.1%) were detected in prepacked products not presented as intentional allergenic ingredient and which did not carry a precautionary advisory label.
Cross-contamination and cross-contact are interchangeable terms that are commonly used to define how a residue or trace amount of an allergen is unintentionally transferred into another product. Cross contact is a better a term because cross contamination is where pathogenic bacteria from contaminated non-ready to eat food is transferred onto ready to eat food. Thorough cooking will destroy non-spore forming bacteria but not normally allergens.
Cross contact can happen directly or indirectly. Direct contamination can happen when an allergen already present in a finished product is removed. Indirect contamination can occur when unintentional allergens are transferred by food and hand contact surfaces and airborne particulates or when a product is cooked in water or oil contaminated with traces of an intentional allergenic ingredient.
Understanding the physical characteristics of an allergen is important. Powders can easily disperse into the air and contaminate food contact surfaces, protective clothing and food products; liquids can drip or splash onto other food products during food preparation and cooking; solid pieces or fragments can deliver a much higher dose of allergenic material to the consumer4, and sticky or cooked residues can be difficult to remove from food contact surfaces.
Food safety management and HACCP systems must evaluate and control the risk of allergenic hazards from supplier to consumer. A control measure can prevent, eliminate or reduce a hazard to an acceptable level. Determining a safe level is difficult as most allergens do not have a safe threshold.
Use approved/reputable suppliers for all purchases. Visually check deliveries for spillages and reject products contaminated with allergens. Store allergenic and non-allergenic products in clearly labelled and dedicated containers, especially open packets of food. Keep tree nuts, peanuts and sesame seeds on lower shelves. Use dedicated scoops for bins (milk powder, sugar and flour).
Cleaning is an effective method for removing an allergen residue. Always clean non-allergenic preparation areas first. Use hot water, detergent and a single use disposable cloth. Utensils, cutlery and crockery should be prewashed before they are put into a dishwasher.
Hands are a common vehicle for transferring allergens from one surface or product to another. Wash hands before preparing food or drink for a customer with a food allergy. Protective clothing is another vehicle of contamination and may need to be changed, especially after working with flour and other food dusts.
Think about the order of production and distance. Prepare non-allergenic food products or specific allergy requests before anything else. Wheat flour dust can travel through as airborne particulates. Good hygiene practices and a minimum distance of 2 metres is recommended for an area designated for preparing gluten free products5.
Allergen residues or traces may be present on equipment shared between food products containing different allergenic ingredients during preparation and cooking. Use dedicated or clean equipment. Purple is a common colour choice to designate equipment for customers with food allergies and other hypersensitivities.
Cooking does not generally destroy allergens. Different products containing allergenic ingredients are occasionally cooked in the same water or oil. Traces of allergens may be present from previously cooked foods and can cause an allergic reaction to anyone who is allergic to them. If practical use fresh water and a dedicated fryer for customers with specific food allergies or find an alternative cooking method. Unintentional allergens can also contaminate other products in an oven. Think about how airborne flour dust could cross contact with other products. Place non allergenic products above those with allergens or use trays to catch drips.
Finally, consumers rely on accurate information provided by the food business to make a safe choice. Always clearly communicate any risk of cross contamination. State which products can be safely modified to exclude an allergen and highlight them in the allergen file (matrix).
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1. Birmingham City Council (2019). Restaurant banned from serving food to customers with allergies. [Online]. Available at: https://www.birmingham.gov.uk/news/article/443/restaurant_banned_from_serving_food_to_customers_with_allergies ( Accessed on 5 October 2019)
2. Durham Council (2019). Restaurant prosecuted for traces of nuts in dish [ Online]. Available at: https://www.durham.gov.uk/article/22038/Restaurant-prosecuted-for-traces-of-nuts-in-dish ( Accessed on 5 October 2019)
3. Knold Seafood (2019.) Ibiza holidaymaker with seafood allergy ‘could have died’ from meals made with contaminated utensils. [Online]. Available at: https://www.knoldseafood.com/ibiza-holidaymaker-with-seafood-allergy-could-have-died-from-meals-made-with-contaminated-utensils/ (Accessed on 5 October).
4. Food and Drink Europe (2013)Guidance on Food Allergen Management for Food Manufacturers. [Online]. Available at: https://www.fooddrinkeurope.eu/uploads/press-releases_documents/temp_file_FINAL_Allergen_A4_web1.pdf
5. Miller K, McGough N, Urwin H. 2016 Catering Gluten-Free When Simultaneously Using Wheat Flour. Journal of Food Protection, Vol. 79, No. 2, 2016, Pages 282–28