Contamination of food

Safe food Food that is free from contamination and will not cause the consumer illness or harm.

Contamination of food Contaminants are anything in food that could cause illness, injury or discomfort to the person eating the food. It could also be something that is just unpleasant and should not be in food. Possible food hazards are all around us and could come from anywhere in the environment and even from food handlers themselves.

Contamination hazards Physical (e.g. glass, packing materials, jewellery, fingernail, blue plaster, bodies of pests) Chemical (e.g. cleaning and disinfection chemicals, agricultural chemicals on food, pest control chemicals, dissolved metals from containers) Biological (e.g. bacteria can spoil food or cause illness, viruses, fungi such as mould and yeasts, poisonous foods, microscopic parasites) Allergens - these are a hazard to any person with an allergy to a particular food or ingredient

Physical contamination Physical contamination can cause illness and harm but more frequently is the cause of customer dissatisfaction and complaints. Which of these could cause illness or harm? Dirt from vegetables Fingernail Blue plaster Tomato plant stem Broken glass Earring Dead cockroach Hair Pieces of chicken bone Small pebble Packing case staple Button Mixing machine bolt String from mop Pen top Date label 10p coin Bay leaf Tea bag

Chemical contamination Chemicals can accidentally get into food from different sources. Some chemicals could cause harm to the consumer, others may cause mild irritation or discomfort and some may simply change the taste of food. Kitchen chemicals such as detergents, disinfectants, sanitiser, machine oil, pesticides, de-greaser. Wrong amounts of additives in foods, chemical sprays on fruits and vegetables. Incorrect use of containers causing chemical reaction. Chemicals getting into water supply.

Avoiding contamination Good, thorough and ongoing staff training. Premises and equipment in good repair. Lockable storage for chemicals. Strict rules on staff uniform, head wear and no jewellery. Wash foods such as dirty vegetables thoroughly. Undo packaging away from food. Take extreme care with pesticides.

Allergens Some people can have an allergic reaction to certain foods and ingredients that do not cause problems for other people. Some reactions can be very serious and even fatal (anaphylactic shock). The foods most commonly linked with allergies are: Nuts (especially peanuts), nut oils and some seeds such as sesame Milk and other dairy products Flour and other wheat products Different fruits, for example strawberries Chocolate

Avoiding hazards from allergens Retain food labelling Separate preparation areas Coded equipment Menu information Fully informed staff Removing top allergy-related foods from the menu.

Biological contamination This is the main cause of food poisoning and most is caused by bacteria. Some bacteria are useful and harmless and are used in the making of cheeses, yoghurt, fizzy drinks, and in medicines. The bacteria that can cause illness are called pathogens.

Bacteria Single cell organisms that cannot be seen without a microscope. Even when food is contaminated with dangerous amounts of bacteria it cannot be detected by sight, smell or taste. It only takes very small amounts of pathogenic bacteria to cause illness or for spoilage bacteria to cause food to ‘go off’.

Likely origins of pathogenic bacteria Raw food, especially from animal sources but also cereal crops, salads and vegetables. Water, if untreated or contaminated. Soil which may be present on vegetables and salads. From human hands, hair, cuts, burns, intestines, coughing, sneezing and so on. Air, dust, food waste - bacteria are present widely in the environment. Pests and pets, fur, droppings, saliva, paws. Animal and human intestines (butchery contamination, not washing hands properly).

Cross-contamination Cross-contamination is the transfer of pathogenic bacteria from contaminated food such as raw meat to ready-to-eat foods. These foods are often involved in food poisoning outbreaks so are called high risk foods.

Routes The path along which bacteria are transferred from the source to the food is called the route. An example would be: A cloth is used to wipe down an area where raw chicken has been prepared. The same cloth is then taken to wipe some spilt salad dressing in the salads section. Then it is taken to wipe the area where savoury flans are being cut for a buffet. The bacteria route is: raw poultry to salads to pastry.

Vehicles Bacteria cannot move around on their own. They rely on other ways, such as: Unwashed hands touching different foods and surfaces. Allowing raw and cooked food to touch or raw food dripping onto high risk food. Cloths, knives and utensils, equipment, work surfaces. Any food surface that has not been properly cleaned. These things are called vehicles of contamination and can very easily be the cause of cross-contamination.

Preventing cross-contamination Remove bacteria sources where possible. Use separate preparation and storage areas for different types of food. Take great care to avoid cross-contamination with cloths, hands, contact surfaces and so on. Use colour-coded equipment and clean and disinfect surfaces and equipment thoroughly. All pests/pets must be excluded.

Avoiding biological contamination Follow the food safety procedures for your workplace and the procedures learned on your course. Use colour-coded equipment where it is available. Use fridges properly, don’t overload, use the correct fridge or position food correctly in the fridge. Label and date all foods, rotate stock and discard foods passed use-by date. Make sure you have excellent standards of personal hygiene. Wash hands thoroughly and frequently.