Cross Contamination
What Is Cross Contamination?
Cross Contamination is the term used to describe the transfer of bacteria from a source to a high risk food, eg cooked meat products, dairy products, egg dishes etc (High protein foods). Sources of food poisoning bacteria are raw foods such as raw meat and poultry, humans, insects, animals and birds, rodents, dust, refuse and waste food.
The bacteria on these sources can pass onto high risk cooked food directly or indirectly.
Direct contamination occurs by the source of bacteria touching the high-risk food.
Indirect contamination occurs, where the bacteria are passed from the source to the high-risk food via something else such as a worktop, hands, equipment and cloths.
Indirect contamination is the most common type of cross contamination and it occurs in food premises because of ignorance, inadequate space, poor design and bad food handling practices by staff.
Some Examples of Cross Contamination:
- Handling raw food, which carries bacteria then handling cooked food. The bacteria pass from raw food onto the hands and then the hands transfer bacteria directly to food or onto work surfaces., cloths and equipment and onto the cooked food.
- Failure to wash hands after visiting the toilet. This allows bacteria from the bowel to be transferred from soiled fingers to foods and equipment resulting in high-risk food becoming contaminated.
- Flies and insects transfer bacteria from animal excrement to food, rats and cockroaches bring bacteria from sewers and drains into the kitchen.
- Equipment covered with dirt and-food debris harbours bacteria and contaminates food.
- Storage of raw food above or next to high risk food; for example, if raw meat is stored above cooked food, blood and fluids may drip onto the cooked food and contaminate it.
How to prevent Cross Contamination
- Keep raw and cooked foods separate. Store raw food in one refrigerator and cooked food in another. If this is impossible, make sure the cooked food is stored above raw food.
- Keep food covered. This prevents contamination from insects, flies etc.
- Do not use the same equipment or surfaces for cutting or preparing raw food then cooked food. If this is impossible, make sure that equipment and surfaces used for raw food are thoroughly cleaned and sterilised before cooked food is used on them.
- Make sure insects, rodents, pets and birds are kept out of the food room. These have unhygienic habits and can spread bacteria directly onto food or to places where they may be picked up on food.
- Always wash hands after any action that could contaminate hands, such as visiting the toilet, after handling waste food and after handling raw food as they are all sources of bacteria which can be transferred to food.
- Keep the food premises clean and maintain high standards of cleanliness and personal hygiene.
- Do not allow rubbish to accumulate.
- Use a colour coding system for equipment such as chopping boards and knives.
Footnote
This guidance is one of a series on Food Hygiene Practices produced by the Hertfordshire and Bedfordshire Environmental Health Officers Food Group.
If you require further advice, please contact the local Environmental Health Department.