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IFST Advisory Statement "Don’t Spread Germs: Avoiding Cross-Contamination in the Home

The Institute of Food Science & Technology has authorised this Advisory Statement, dated May 2008, as an IFST contribution to the 16th National Food Safety Week, which runs from 9-13 June 2008.

Cross-contamination (spreading of germs) is a major cause of food poisoning. Food poisoning is preventable - avoiding cross-contamination is simple and important. Here we offer ten pointers for avoiding cross-contamination in the home.

Germs (including food-poisoning organisms) exist harmlessly in many natural environments, for example farmyards and farm animals, poultry and wild birds and on fields that are fertilised with 'organic' manure. People and animals suffering from food-poisoning can also shed large numbers of germs, either through sickness or diarrhoea. Germs also occur on and in the skin, and so on unwashed hands.
Insects, rodents and other pests ('vermin') as well as domestic pets also harbour germs and can transfer them from one place to another.

Germs are found in unwashed foods, raw foods and foods that are to be cooked. If the cooking is thorough, many types of germs (though not all) are killed, so their presence in raw foods such as meat, poultry, fish, eggs and vegetables may not be important provided these foods are cooked properly. However, these raw foods may easily spread contamination to other, unpackaged, ready-to-eat foods such as cheese, sandwiches, salad vegetables, cooked meats, pies and desserts.

Cross-contamination is the transfer of germs to uncontaminated food, and is especially dangerous in the case of ready-to-eat food. Germs do not always cause food-poisoning, although for some people even low numbers may constitute a risk. The risk of food-poisoning greatly increases if germs are allowed to multiply ('breed'), either in the food itself or in a dirty place that can contaminate the food with large numbers of germs. Foods that are not eaten immediately after thorough cooking should be stored in the 'fridge once cooled.
Cross-contamination, in its simplest form, occurs, for example, if blood or other liquid from raw meat drips directly onto a ready-to-eat dessert placed at the bottom of the 'fridge, or in the shopping bag if the food is not properly wrapped. Almost anything that is dirty can also transfer germs indirectly from a source of contamination to uncontaminated foods. Here are a few examples of common routes of cross-contamination:
• hands
• dishcloths, teatowels, handtowels, aprons and floor cloths (especially if allowed to become dirty or remain wet)
• work surfaces
• packaging used for raw foods
• pets (especially if allowed to walk on the worktop)
• pets' bowls
• vermin
• dirty rinse water and washing up bowls
• waste bins and dustbins
• children's toys
• anything that has been outside
• dirty utensils or utensils that have been in contact with raw egg, meat or vegetables, for example chopping boards, knives, bowls and food processors.

Ten Points for Avoiding Cross-Contamination in the Home

Wash raw foods that are to be eaten raw and choose foods that have been processed for safety. Remember that raw foods may come from farms, market gardens or be home-grown. Germs exist naturally in the environment, even in the most hygienic growth conditions, so we must assume that raw food might be contaminated and keep it separate from ready-to-eat-food. This applies to all raw foods, even if 'free-range' or 'organic' and whether you have bought them in the village store or the supermarket, or are home-grown. The World Health Organisation recommends that consumers should, for example:
** always buy pasteurised milk
** thoroughly wash certain foods eaten raw, such as un-pre-washed lettuce, other salad vegetables and fruit.
Keep raw and cooked foods apart during storage, either in the fridge, the freezer or the larder. Store ready-to-eat food above raw meat and poultry. Commodities such as un-prepacked salad vegetables may be placed in the middle. Cover all food and place on a plate any food that is likely to drip.
Use different utensils for preparing raw and cooked foods. Don't, for example, prepare a raw chicken and then use the same unwashed cutting board and knife to carve the cooked bird. After preparing raw foods in a food processor, clean the parts thoroughly using hot water with detergent or in the dishwasher. Remember that using separate utensils is just as important when cooking on the barbeque! Take the same precautions with cutting boards, utensils and other items that contain an antibacterial as with ordinary
Institute of Food Science and Technology Advisory Statement
ones. Germs breed less quickly on those with built-in antimicrobial, but if they become contaminated they are just as liable to transmit contamination.
Wash hands, including finger-tips, thoroughly with soap and water for at least 20 seconds and dry them thoroughly before you start preparing food. Do this repeatedly during food preparation - after every interruption and always if you have had to change the baby's nappy or have been to the toilet; or after combing or touching your hair, nose, mouth or ears; or after eating, smoking, coughing or blowing nose; or after handling waste food or refuse; or after handling dirty cloths, crockery etc; or after shaking hands; or after touching shoes, the floor or other dirty surfaces. After preparing raw foods such as fish, meat, or poultry, wash your hands again before you start handling other foods. Rings can harbour germs - remove them before preparing food!
Keep all kitchen surfaces meticulously clean because every food scrap, crumb or spot is a potential reservoir of germs. The most important aspect of cleaning is physical removal of germs using hot water, a detergent and 'elbow grease' to remove food residues, especially fat. Disinfectants only work at their best on a surface that is already clean!
Frequently change cloths that come into contact with plates and utensils and wash in very hot water before re-use. After use, dry dishcloths, teatowels, handtowels and aprons rapidly to stop any germs from breeding. Don’t use floorcloths for cleaning surfaces used for food preparation or for cleaning plates and utensils. Wash and dry floorcloths after use on floors!
Dry the washed plates and utensils by allowing them to drain naturally and rapidly or by using a dishwasher! These are the most hygienic methods.
Protect foods from domestic pets, insects and rodents. Do not allow domestic pets to walk on kitchen worktops! Remember, too, that smaller pets such as birds, rodents, reptiles and turtles also harbour germs.
Always use clean, drinking-quality water for food preparation and for washing up. After washing vegetables that are to be cooked, change the water before washing ready-to-eat foods. However do not wash raw meat, poultry or fish. Apart from being ineffective in removing germs that cling to the meat or skin, washing would lead to contamination of the sink and, by splashing, contamination of other surfaces surrounding the sink that might contaminate other foods.
Do not prepare food for others if you are sick or have a skin infection. Cover cuts with waterproof plasters.
Additional precaution
If you suspect cooked, or ready-to-eat food might be contaminated, don't serve it or eat it!
Food-poisoning is preventable - avoiding cross-contamination is simple and important!

Ralph Blanchfield | alfa
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