Bacteria and viruses are hitchhikers and they need help to get from one place to another. Most of the time we provide the help when we are careless and allow cross-contamination to happen. The end result can be food poisoning.

What is cross-contamination?

Cross-contamination occurs when bacteria and viruses are transferred from a contaminated surface to one that is not contaminated. The bacteria and viruses can come from people, work surfaces or equipment and other foods. For example, it can happen when bacteria from the surface of raw meat, poultry and raw vegetables with visible dirt (such as unwashed potatoes), are transferred onto ready to eat food, such as green salads, rice or pasta salads, cooked meats or poultry, or even fruit. The bacteria on the raw food are killed when the food is cooked, but the ready to eat food gets eaten without further cooking - bacteria and all.

How are the bacteria transferred?

Hands are among the obvious culprits in transferring bacteria from raw to ready to eat food, but direct contact with raw foods, dirty chopping boards, knives and other cooking implements can also spread the contamination. Chopping boards, plates and knives that have been in contact with raw food need to be carefully washed with warm water and detergent, then rinsed and thoroughly dried before being used for ready to eat foods. Incorrectly storing raw food in the fridge by allowing it to come into direct contact with ready to eat foods, or allowing raw meat juices to drip onto cooked foods, fruit and other ready to eat food, can also cause cross-contamination. Raw foods should always be treated as though they are contaminated.

How should raw and ready to eat food be stored?

Raw food, such as meat, poultry or fish should be stored in a rigid container or at the bottom of the fridge to prevent it coming into contact with ready to eat food or allowing meat juices drip onto other food. Ready to eat food should be stored covered in the fridge to further reduce the risks.

What kind of chopping board is best to avoid cross contamination?

In the home it really doesn't matter whether you have wooden, plastic or glass chopping boards so long as they are kept really clean and in good condition. The porous nature of wood makes it advisable to use plastic or glass chopping boards for raw meat, poultry and seafood. It may be easiest to have two boards - one for raw food and one for ready to eat food. All chopping boards should be scrubbed with hot water and detergent after preparing raw foods. Plastic chopping boards are good as they can be washed at high temperatures in the dishwasher. However, any board should be replaced when its surface becomes scratched because bacteria can hide in the scratches.

Information from the Food Safety Information Council