Cross-contamination in a professional kitchen: how it happens and how to stop it

Cooking kills most harmful bacteria. Ready-to-eat food, such as salad, cooked meat, sandwiches, desserts and bread, is not cooked again before it is eaten. Cross-contamination is when bacteria reach that food from somewhere else. It happens in three main ways:

• Direct: raw food touches ready-to-eat food, for example raw chicken next to cooked ham on a tray.
• Through something in between: hands, boards, knives, tongs, cloths, probes or worktops carry bacteria from raw food to ready-to-eat food.
• Drips: juices from raw meat drip onto food below.

The FSA's guidance is built around E. coli O157, which can be found in raw meat, raw milk and soil on vegetables, and can cause serious illness, including kidney failure. The same steps protect against other bacteria too.

Allergen cross-contact is a different hazard: an allergen getting into a dish that should not have it. Cleaning to kill bacteria does not prove an allergen has gone. Our allergen matrix guide covers it.

Our advice What it looks like on a real shift:

• Raw chicken is portioned on a board, then the same board is used for salad garnish.
• A probe goes into a raw burger, then into cooked ham, with only a probe wipe in between.
• Raw meat sits on the top shelf of the fridge and drips onto desserts below.
• A chef handles raw meat, then plates up without washing their hands.
• One cloth wipes the raw prep bench, then the pass.
• The same slicer is used for raw bacon and cooked ham.
• A delivery box that held raw meat is put on a prep table.
• A chef in gloves portions raw chicken, answers the phone, then garnishes a salad in the same gloves.
• Someone opens the fridge with raw-chicken hands, and the next person uses the same handle and makes a sandwich.

Law in all four nations The law says food must be protected against any contamination likely to make it unfit or harmful, at every stage. Everything food touches must be effectively cleaned and, where necessary, disinfected, often enough to avoid any risk of contamination. You need enough hand basins in the right places. Food handlers must keep themselves clean, wear clean, suitable clothing, and be supervised and instructed or trained. The law also asks for food safety procedures based on HACCP, with records that fit the size of your business.

• Law in England, Wales and Northern Ireland England: the Food Safety and Hygiene (England) Regulations 2013. Wales: the Food Hygiene (Wales) Regulations 2006. Northern Ireland: the Food Hygiene Regulations (Northern Ireland) 2006.
• Law in Scotland The Food Hygiene (Scotland) Regulations 2006.

These enforce Regulation (EC) 852/2004 as it applies in the UK. The law does not say how to keep raw and ready-to-eat food apart. The guidance below does, and your inspector may use it when looking at your kitchen.

Keep raw and ready-to-eat food apart at every step: delivery, storage, defrosting, preparation, cooking and serving, in this order of preference:

1. Best: separate rooms, staff, equipment and utensils.
2. Next: an area kept for ready-to-eat food only.
3. Last resort: separating by time. Prepare ready-to-eat food first, then raw, then clean and disinfect the area before ready-to-eat food goes back on it.

Guidance in England, Wales and Northern Ireland This is the order the FSA's E. coli guidance sets out. It calls separating by time the hardest to achieve.

When you separate by time, put food on a board or in a container, never straight on the worktop.

Guidance Do not wash raw meat or poultry. It splashes bacteria around the sink and onto anything near it.

Separate fridges for raw and ready-to-eat food are best. In a shared fridge, keep raw meat, poultry, fish and eggs covered and below ready-to-eat food, so nothing can drip onto it (eggs in detail: our eggs guide). Keep unwashed fruit and vegetables apart from ready-to-eat food and above raw meat.

• Guidance in England, Wales and Northern Ireland The FSA says raw food must be stored below ready-to-eat food unless other measures are in place, and that ready-to-eat food should be placed so raw food does not have to be lifted over it.
• Guidance in Scotland CookSafe says that in shared storage, raw foods must be stored on the bottom shelves and always below ready-to-eat foods.

Defrost raw food covered, at the bottom of the fridge below ready-to-eat food, or in a separate area away from other food.

Have separate boards, knives, tongs and containers for raw and ready-to-eat food that staff can tell apart at a glance, and store and wash them separately. Our chopping board colours guide has a free wall chart.

• Guidance in England, Wales and Northern Ireland The FSA says shared boards and utensils should go through a full dishwasher cycle, or another form of heat disinfection, between raw and ready-to-eat use.
• Guidance in Scotland CookSafe says boards and utensils should never be shared between raw and ready-to-eat food.

Slicers, mincers and vacuum packers. Keep separate machines for raw and ready-to-eat food.

• Guidance in England, Wales and Northern Ireland The FSA says complex equipment such as vacuum packers, slicers and mincers should not be used for both unless it is fully taken apart and disinfected between uses, and that for slicers and mincers this cannot be done properly during a normal working day.
• Guidance in Northern Ireland Safe Catering says complex equipment, such as slicers, used for ready-to-eat food should not be used for raw food.

How to clean them: our cleaning schedule guide.

Guidance Washing your hands properly, at the right times, is one of the best ways to stop bacteria getting from raw food to ready-to-eat food.

Law in all four nations Everyone working where food is handled must keep themselves very clean. You need enough hand basins, in the right places, kept for washing hands. Each needs hot and cold running water, soap or another way to clean hands, and a hygienic way to dry them. Where needed, food must be washed somewhere else, not in the hand basin. Food vans, market stalls, marquees and kitchens at home have a shorter rule: "appropriate facilities" for "the hygienic washing and drying of hands". Our hand wash basins guide covers both.

When to wash your hands

Guidance Wash your hands:

• when you come into the kitchen and before you start work, including after a break
• before you touch ready-to-eat food
• after touching raw meat, poultry, fish or eggs, unwashed fruit and vegetables, or their packaging
• after going to the toilet
• after cleaning, and after touching or emptying bins
• after touching your face, hair or nose, blowing your nose, coughing or sneezing
• after touching a cut or changing a dressing
• after eating, drinking or smoking
• after using a phone, and after touching light switches, door handles, the till, money or the card machine
• before preparing food for a customer who has told you about a food allergy
• after taking off a dirty apron, and before putting on a clean one

This list brings together the FSA's guidance for England, Wales and Northern Ireland and CookSafe's in Scotland.

How to wash your hands

Guidance in England, Wales and Northern Ireland The FSA's method, also used in Northern Ireland's Safe Catering:

1. Wet your hands under warm running water and put liquid soap on your palm.
2. Rub your palms together to make a lather.
3. Rub the palm of one hand along the back of the other and along the fingers, then swap hands.
4. Put your palms together with your fingers interlocked and rub between the fingers.
5. Rub around each thumb, then rub your fingertips against the other palm.
6. Rinse with clean running water and dry your hands thoroughly on a paper towel. Turn the tap off with the towel, then throw it away.

Guidance in Scotland CookSafe uses the same rubbing steps and adds: if your hands are not visibly clean after washing, wash them again.

Guidance No food safety guidance we read gives a number of seconds. The FSA says effective hand washing takes time. The NHS's everyday advice is about 20 seconds, as long as it takes to sing Happy Birthday twice.

Drying and taps

Guidance in England, Wales and Northern Ireland Dry your hands thoroughly, because bacteria spread more easily from wet or damp hands. The FSA recommends single-use paper towels and does not recommend reusable towels. Taps can carry bacteria, so turn them off with your paper towel, not your clean hands. The FSA calls taps you do not work by hand, such as sensor, elbow or foot taps, good practice. Short lever taps you can push with the back of your hand are a good alternative.

Guidance in Scotland CookSafe also says to dry your hands on a single-use towel and turn the tap off with it, and to consider fitting taps you do not work by hand.

The hand basin

Law in all four nations A hand basin is for washing hands.

Guidance in England and Wales The FSA's Safer Food, Better Business pack says hand basins should be convenient, with plenty of soap and disposable towels, and asks you to check and refill them often.

Our advice Keep the basin clear. Never wash food, equipment or cloths in it. Check the soap and paper towels during service, not just at opening. How many basins, where, and what vans and home kitchens need: our hand wash basins guide.

Hand gel and hand wash

Guidance Hand gel can add protection after washing. It never replaces washing, and it does not remove visible dirt. If you use gel, the FSA and CookSafe say to choose one that meets BS EN 1500. For extra protection they recommend a liquid antibacterial hand wash that meets BS EN 1499. These two standards are for hands. The disinfectant standards for surfaces, BS EN 1276 and BS EN 13697, are different.

Guidance in Scotland CookSafe recommends hand gel after washing when the risk is higher, for example after handling raw food.

Law in all four nations The law does not require food handlers to wear gloves. It requires them to keep themselves very clean and wear suitable, clean and, where necessary, protective clothing.

Guidance Gloves do not replace hand washing. Gloves pick up bacteria just as hands do. If you use disposable gloves:

• wash your hands before you put them on and after you take them off
• use each pair for one task, then throw them away
• change them whenever you would wash your hands: after raw food or its packaging, before ready-to-eat food, after bins, cleaning, money or the phone, and after touching your face or hair
• change them straight away if they tear or get damaged

• Guidance in England, Wales and Northern Ireland The FSA says gloves should be changed as often as you should wash your hands, and "Gloves are not a substitute for effective handwashing."
• Guidance in Northern Ireland Safe Catering says gloves must be used only once, and changed between tasks, for example after raw meat, poultry, fish or eggs, before ready-to-eat food, after handling money, after emptying bins and after cleaning.
• Guidance in Scotland CookSafe says to think first about whether gloves can be used safely in your kitchen. It says to change them after touching things such as money, before ready-to-eat food, and never to use them instead of washing hands.

Guidance For ready-to-eat food, handle it as little as possible and use clean tongs or other utensils where you can. Gloves, used correctly, are another option. The FSA and Food Standards Scotland say separate gloves for different jobs, for example a different colour for raw food, might help. No guidance we read sets a glove colour.

Our advice Many kitchens use blue gloves because a torn piece is easier to see in food.

Guidance in England, Wales and Northern Ireland The FSA calls door handles, light switches and similar items "hand contact points". Hands touch them between raw and ready-to-eat food, so they can carry bacteria from one to the other. The FSA says they should be on your cleaning checklist and schedule.

Guidance In a kitchen they include:

• door, fridge and freezer handles
• light switches, controls and dials
• taps
• bin lids
• phones and tablets
• the till, card machine and pens
• scales and can openers
• probe thermometer handles

Guidance Two things keep them from spreading bacteria:

• Wash your hands. The FSA says staff on raw and ready-to-eat food can share the till, phone, card machine and switches, because washing hands after raw food and before ready-to-eat food is the main control. Wash your hands after raw food before you open a door or a fridge, not after.
• Clean and disinfect them regularly. Use the same clean-then-disinfect method as your surfaces. No guidance sets how often. The FSA's Safer Food, Better Business pack asks you to decide and write it in your cleaning schedule.

Our advice Clean and disinfect hand contact points every shift, and straight away if someone touches one with raw food on their hands or gloves.

Guidance If one sink is used for both raw and ready-to-eat equipment, clean and disinfect the sink, taps and fittings between uses.

Guidance in Northern Ireland Safe Catering recommends pedal bins, so nobody has to touch the lid.

Phones and tablets

Guidance No guidance we read bans phones in the kitchen. They count as hand contact points: wash your hands after using one, and keep it on your cleaning schedule.

Our advice That includes the phone or tablet you record your checks on, ChefsRecords included. Wipe it with your other contact points. If you are wearing gloves, change them after using it, before you touch ready-to-eat food.

Our advice Change your apron after preparing raw food, before you work with ready-to-eat food, and whenever it gets dirty. A chef at the stove or grill, putting raw food on and taking cooked food off, does not need a new apron each time unless it gets dirty.

Guidance in England, Wales and Northern Ireland Take off watches and jewellery before preparing food, apart from a plain wedding band.

Guidance in Scotland CookSafe says to keep jewellery to a minimum.

Guidance Tell your manager about any cut or sore. Cover it completely with a brightly coloured waterproof dressing, such as a blue plaster, so it is easy to spot if it falls into food.

Our advice Keep nails short and clean.

Clean and disinfect the probe before and after each use. A separate probe for ready-to-eat food is best.

• Guidance in England, Wales and Northern Ireland The FSA says probe wipes reduce the risk but are not enough on their own if one probe goes from raw to ready-to-eat food. It gives boiling water, above 80°C, as an example of something more effective.
• Guidance in Scotland CookSafe says a probe used to check cooking temperatures must be identifiable for use on ready-to-eat food only.
• Guidance in Northern Ireland Safe Catering says to always use a separate probe for checking the temperature of ready-to-eat food.

Checking that your probe reads correctly is a different job: see our probe calibration check guide.

Guidance Clean first, then disinfect. Disinfectant only works on a surface that is already clean. Use a disinfectant or sanitiser that meets BS EN 1276 or BS EN 13697, at the dilution and for the contact time on its label. A sanitiser cleans and disinfects, so use it twice: once to clean, once to disinfect.

Guidance in England and Wales The FSA pack calls a dishwasher "a good way to clean equipment and kill bacteria (disinfect)". Guidance in Northern Ireland Safe Catering calls a dishwasher "one of the most reliable ways to clean equipment and kill harmful bacteria such as E.coli O157", and says steam cleaning and sterilising sinks "can also be effective methods for disinfecting using heat in some circumstances but should be used with care".

Guidance Use disposable cloths where you can and throw them away after each task. Keep separate cloths for raw food areas. Soaking cloths in bleach is not an effective way to disinfect them.

The full method is in our cleaning schedule guide. What to look for on a disinfectant label: our disinfectants guide.

Ask for raw food to arrive apart from ready-to-eat food where you can. If it comes together, check it was kept separate and the packaging is not damaged or leaking. Take off outer packaging before food goes into the kitchen, and never put a box that held raw meat on a prep surface.

Guidance in England and Wales The FSA's Safer Food, Better Business pack says raw and ready-to-eat food delivered together must be kept separate.

More in our delivery checks guide.

Guidance If ready-to-eat food may have touched raw food or its juices, throw it away. Wash, disinfect and dry anything the raw food touched.

Guidance in England, Wales and Northern Ireland The FSA's E. coli guidance lists what to write down: what went wrong, when, which control failed, what you did to correct it, who you told and when, and what you changed so it does not happen again.

Our advice There is no published list. The FSA's E. coli guidance is written for inspectors as well as businesses, so these are questions we would expect:

• Where do you prepare raw food, and where ready-to-eat?
• Which boards and knives are for raw food? How are they washed and stored?
• Is the slicer or vacuum packer ever used for both?
• What does your disinfectant meet, and what is its contact time?
• How are cloths handled?
• Can I see your hand basin? How do staff dry their hands?
• When do staff change their gloves?
• How is the probe cleaned between raw and cooked food?
• Where do you defrost?
• Can I see the fridge?
• What happened the last time something went wrong, and where is it written down?

In Scotland, an officer may also swab a surface to check your cleaning.

ChefsRecords helps you keep a daily record of the checks that show raw and ready-to-eat food are kept apart, with who completed each checklist and when:

• The starter Closing Checks include "Raw food below or apart from ready-to-eat food" and "Surfaces, boards, utensils and equipment cleaned and disinfected". Opening Checks include "Prep surfaces, boards and utensils clean and disinfected" and "Probe working and clean; probe wipes in stock". You can add "Raw below ready-to-eat at opening" too.
• Opening Checks also include "Staff fit for work, in clean workwear, cuts covered", "Hot running water at every sink and hand basin" and "Soap and paper towels at every hand basin". The optional Daily Cleaning Schedule includes "Handles, taps, switches and controls cleaned and disinfected" and "Sinks and hand basins cleaned and disinfected".
• An optional Stock Check includes "Anything defrosting is covered and cannot drip onto other food" and "Raw meat and fish below or apart from ready-to-eat food". An optional Daily Cleaning Schedule includes boards, cloths and "Slicer, mixer and small kit taken apart, cleaned, disinfected".
• When something goes wrong, log it as a near miss or an incident with a photo: "Contamination" for raw juices in food, "Stored Unsafely" for raw food above ready-to-eat food, and "Damaged Goods" for a leaking delivery. Write what you did about it. The app flags a repeat when the same problem is logged in the same area within 30 days. A missed hand wash or glove change can be logged as a Staff incident or near miss, type "Hygiene". Only Managers can see Staff records. A Hygiene or Food Safety staff incident goes in the Inspection Pack; a conduct-only one does not.

"Contamination" covers raw juices in food. "Stored Unsafely" covers raw food above ready-to-eat food. Each can be a near miss or an incident, with a photo.

Not yet: a place to set your board colours, a delivery question about raw and ready-to-eat food arriving apart, or a check that hand basins are clear and used only for hands. Tell us if you would use them.

Which plan. Incidents and near misses are on every plan. Checklists and the Inspection Pack come with Standard and Pro and are open in the 14-day trial.

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What is cross-contamination?

Bacteria spreading from raw food, hands, surfaces, cloths or equipment to food that will not be cooked again, such as salad, cooked meat or desserts.

What are the main types of cross-contamination?

Direct, when raw food touches ready-to-eat food; through something in between, such as hands, boards, knives or cloths; and drips, when raw juices fall onto food below.

How do you prevent cross-contamination in a kitchen?

Keep raw and ready-to-eat food apart at every step, use separate boards and utensils that are easy to tell apart, clean and then disinfect, wash your hands after touching raw food, and store raw food below ready-to-eat food.

Is colour coding a legal requirement?

No. The law says food must be protected from contamination. Colour coded boards are one common way to do it, recommended in guidance in all four nations.

Can I use the same slicer for raw and cooked meat?

Keep separate machines. The FSA says a slicer should only be used for both if it is fully taken apart and disinfected in between, which cannot be done properly during a normal working day.

Do food handlers have to wear gloves?

No. The law does not require gloves. If you use them, wash your hands before putting them on and after taking them off, use each pair for one task, and change them whenever you would wash your hands. Gloves do not replace hand washing.

How often should we clean door handles, taps and switches?

No guidance sets a time. The FSA says hand contact points should be on your cleaning schedule and cleaned and disinfected regularly. Many kitchens do them every shift, and straight away if someone touches one with raw food on their hands.

Is hand gel enough after handling raw chicken?

No. Wash your hands with soap and water. Gel can be used after washing for extra protection, but it does not replace washing and does not remove visible dirt.

Can staff use their phones in the kitchen?

No guidance we read bans it. Treat a phone as a hand contact point: wash your hands after using it, before you touch food, and clean it with your other contact points.

Should I wash raw chicken?

No. Washing raw meat or poultry splashes bacteria around the sink. Cooking it properly kills the bacteria.

Is cross-contamination the same as allergen cross-contact?

No. Cross-contamination is about bacteria. Allergen cross-contact is an allergen getting into food that should not have it, and cleaning to kill bacteria does not prove an allergen has gone.

Is it different in Scotland?

The law is the same, in Scotland's own regulations. The guidance is from Food Standards Scotland and CookSafe, and it is stricter on sharing: it says boards, utensils and containers should never be shared between raw and ready-to-eat food.

Related guides

The chopping board colours guide, the kitchen cleaning schedule guide, the delivery checks guide, the allergen matrix guide, the staff sickness guide, the near miss guide, the EHO inspection guide and the 4Cs of food hygiene guide. In England and Wales, our free food safety plan builder has a cross-contamination section. More guides: the hand wash basins guide, the disinfectants guide and the eggs guide.