Guide Food safety tips for businesses

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3. Cross contamination

Cross contamination is when bacteria spread between food, surfaces, people or equipment.

It's most likely to happen when:

  • Raw food touches (or drips onto) other food
  • Raw food touches (or drips onto) equipment or surfaces
  • People touch raw food with their hands.

So, if raw meat drips onto a cake in the fridge, bacteria will spread from the meat to the cake.

If you cut raw meat on a chopping board, bacteria will spread from the meat to the board and knife. If you then use the same board and knife (without sanitising them thoroughly) to chop a cucumber, the bacteria will spread from the board and knife to the cucumber.

Hands can also spread bacteria

If you touch raw food and don’t wash your hands thoroughly you can spread bacteria to other things you touch. People also carry bacteria in their bodies, so if someone touches their mouth, nose, any open cut, or when they stifle a cough or go to the toilet, they will end up with many more bacteria on their hands. This is why it is so important to wash hands regularly and after using the toilet.

If you can't clean equipment, you can't use it for everything

Complex equipment that can't be completely disassembled and put through a commercial dishwasher can't be used for raw and ready to eat foods as it will be impossible to adequately disinfect. Complex equipment includes slicers, vacuum packing machines, mincers, food processors, electrical machinery and other similar items that cannot be fully submerged in cleaning solutions or subject to heat treatment up to 820C. You could use it just for raw food, but must make it clear it cannot be used for anything that won't be cooked.

By avoiding cross contamination, you can stop bacteria spreading.

What you need to do:

  • Keep raw and ready-to-eat foods separate.
  • Clean and sanitise surfaces and equipment thoroughly before you start to prepare food and after they have been used with raw food.
  • Keep areas where you prepare raw foods separate from areas where you handle ready to eat foods.
  • Where possible have separate utensils and equipment, knives and chopping boards for raw and cooked foods, preferably using different colours to make it clear.
  • Keep staff handling ready to eat foods separate from staff and areas where raw foods are handled as much as possible.
  • Wash your hands thoroughly after touching raw food, coughing/sneezing, touching your mouth or nose or going to the toilet.

How to check:

  • Supervise cleaning and food handling.
  • Check that raw and ready-to-eat foods are kept apart when they are stored, prepared and displayed.
  • Make sure that your staff know how to avoid cross contamination.