Trading Standards Institute Advice

Cross-contamination of food

This leaflet is for all food businesses, including those involved in catering, food production, food preparation, retail premises, restaurants, pubs, cafes, and fast-food shops.

What is cross-contamination?
Cross-contamination describes the transfer of harmful micro-organisms on to high-risk food. High-risk food is generally described as food that has been processed (cleaned or cooked) to make it safe and that won't need any more processing before it's eaten.

The most common type of cross-contamination is from raw food to ready-to-eat cooked food - either hot or cold. Cross-contamination can happen in a number of ways:

Direct cross-contamination - allowing raw food that has food poisoning bacteria on it to touch cooked or ready to eat food.

Indirect cross-contamination - where something helps the organisms move from one place to another. We call these 'vehicles' of contamination. Just as you would get in your car or on a bus to travel from one place to another, micro-organisms will hop on to something to travel from raw to cooked food. This is called the route of contamination. Common vehicles of contamination include food-preparation surfaces, chopping and cutting boards, knives and utensils, cloths and hands.

Raw food dripping on to cooked food can also cause contamination. This often happens in the fridge where food is uncovered and raw food is placed above cooked food.

Why does it matter?
Cross-contamination is a very common cause of food-related illness.

By law, food handlers must protect food from contamination of any kind, including harmful micro-organisms (pathogens) that cause food poisoning. We can't see these organisms with the naked eye, which can make them hard to control. The best approach is to expect all raw foods to be contaminated and process them to reduce the bacteria to a safe level.

Your food safety management system will help you to identify these hazards and the controls you will need to use to keep the food safe.

You can control contamination by getting rid of the source (the place the micro-organisms came from) or 'breaking the chain'. This means putting something between the source, the vehicle and the food. Most of the controls you will use are general ones and apply to all food preparation and service areas.

Training food handlers
Training food handlers is a very important part of preventing cross-contamination.

Food handlers must be trained to store food correctly, especially in the fridge where high-risk foods are kept. All food should be labelled, dated and covered to protect it and the other food in the fridge. Cooked food items should be put at the top of the fridge, and raw foods should be put at the bottom.

This should stop cross-contamination due to dripping or direct contact with other food.

Ideally, separate fridges should be used for storing raw food and ready-to-eat food.

Keep raw and cooked foods separated
You should think about your work flow, which means the way you process food through your system from its raw to cooked state.

The best way you can control this is by keeping raw and cooked foods apart. This could mean having completely separate work areas or preparation surfaces (such as tables and cutting boards).

However, if you don't have much room this may not always be possible, so you would then control contamination by thoroughly cleaning and disinfecting all contact surfaces, utensils and equipment between tasks, and especially if you are moving from handling raw to cooked food.

Cleaning
Your premises and equipment should be easy to clean and disinfect (hard, smooth surfaces are best), and they should be designed without any areas where food debris and waste could build up.

You must also clean your cleaning equipment such as mops, brooms and cloths.

Cloths used in the food prep area can be a problem. You won't clean anything with a dirty cloth or remove micro-organisms - you will just spread them around. You need to decide which kinds of cloths you will use. You could use different coloured cloths for different areas or jobs - this is called colour coding. Disposable cloths should be used for tasks that involve raw meat and fish and they should be thrown away after you have used them once, or change them if you use reusable cloths. You must change any reusable cloths regularly and they must be thoroughly hot washed, rinsed and dried before you use them again.

Keep food handling to a minimum
You should plan to make sure food is handled as little as possible.

You should use utensils rather than your hands, but always use different ones for raw food and cooked food - you may also want to colour-code them. This should also apply where you are handling meat products and vegetarian foods

You should consider using disposable gloves. When gloves are used it is essential that enough gloves are available so that you can change them as regularly as you would wash your hands.

Food handlers and hand hygiene
You need to make food handlers aware of how important personal hygiene is.

Dirty protective clothing can contaminate the food. Hand washing is very important, particularly when dealing with raw then cooked foods.

Hand-washing facilities
Hands are the most frequently used utensil in a kitchen.

As the 'business operator', you must provide a separate hand wash basin with hot and cold running water, soap, preferably liquid, anti-bacterial and a method of hand drying, preferably paper towels.

You must check that all of these are being used and that food handlers are washing their hands properly - not just rinsing them under the cold tap.

Show food handlers how to wash their hands properly, and check that they do so.

Food waste disposal
Clean as you go.

You should get rid of raw food waste, such as vegetable peelings and meat scraps, and thoroughly clean and disinfect anything they have been in contact with.

If your work space is untidy, with both raw and cooked foods in the same area, there will be an increased risk of cross-contamination.

More information
You will find further guidance in our other leaflets on this website. Information can also be found on the Food Standards Agency website.

Alternatively, contact your local environmental health service for advice.

Please note
This leaflet is not an authoritative interpretation of the law and is intended only for guidance.

© 2017 itsa Ltd.