Cross-contamination is the transfer of harmful germs from one food, surface, person or piece of equipment to another. The classic danger is germs moving from raw food to ready-to-eat food. Preventing it is mostly about separation and order of work.
The three ways germs travel
Cross-contamination happens through three main routes. Recognising them helps you stop it:
- Food to food — raw juices dripping onto ready-to-eat food
- Hands to food — touching raw chicken, then a salad, without washing
- Equipment to food — using the same unwashed board, knife or cloth for raw and ready-to-eat food
Separate raw and ready-to-eat foods
Ready-to-eat foods (salads, cooked meats, bread, desserts) will not be cooked again to kill germs, so they must be protected from raw foods at every stage.
Use separate equipment, or thoroughly clean and sanitise between tasks. Many kitchens use a colour-coded chopping board system to keep tasks apart.
- Red — raw meat
- Blue — raw fish and seafood
- Yellow — cooked meat
- Green — salad, fruit and vegetables
- Brown — root vegetables
Storage order in the fridge
Store food so that raw items can never drip onto ready-to-eat items. The safe order from top to bottom puts ready-to-eat foods highest and raw meats lowest.
- Top shelves — ready-to-eat and cooked foods
- Middle — raw fish and seafood, then raw whole cuts of meat
- Bottom shelf — raw poultry and raw mince (the highest-risk items)
- Keep all food covered and in food-grade containers
Practical examples
- Use a red board for raw chicken and a green board for salad — never the same board for both.
- Store raw chicken in a sealed tray on the bottom shelf, below the cooked ham.
- Change or wash and sanitise the cleaning cloth used on a raw-meat bench before wiping a salad bench.
Key points to remember
- Germs travel food-to-food, hand-to-food and equipment-to-food.
- Keep raw and ready-to-eat foods separate at every stage.
- Use separate or colour-coded boards and utensils, or clean and sanitise between tasks.
- Store raw poultry and mince on the bottom shelf, below ready-to-eat food.