Defrosting food safely in a commercial kitchen: methods, times and refreezing

Law in all four nations One short paragraph of food hygiene law covers defrosting: point 7 of Chapter IX, in Annex II of Regulation 852/2004. In plain words, it asks four things of every food business:

• thaw food so that germs get as little chance as possible to multiply or make toxins;
• keep the food, while it defrosts, at temperatures that do not put anyone's health at risk;
• deal with the liquid that runs off as food thaws. This one is worth reading in the law's own words: "Where run-off liquid from the thawing process may present a risk to health it is to be adequately drained.";
• once it has defrosted, handle the food so that the risk stays low.

The same chapter asks you to protect food from contamination at every stage, which covers drip from a defrosting joint onto a tray of salad, and not to break the cold chain, apart from short periods for practical reasons such as preparation and service, as long as that does not put health at risk.

Law in all four nations The law does not say "use the fridge" or set a time. It sets the outcome and leaves the method to you. Every food business must have food safety procedures based on HACCP. Our advice Write the way you defrost, and how you check it, into your food safety plan.

Law in England, Wales and Northern Ireland Food that needs to be kept chilled must not be kept above 8°C. That covers cooked and ready-to-eat food defrosting in a fridge. Raw food that will be cooked before it is eaten is outside the 8°C rule, but the defrosting duties above still apply to it. The rules also allow short periods above 8°C for some reasons, one of which is "the defrosting of equipment". That means a fridge running its own defrost cycle, not food being thawed: it is no excuse for food left out to defrost. Our advice Defrost raw food in the fridge too. Being outside the 8°C rule is not a reason to leave it out.

Law in Scotland Scotland's law sets no chill figure. Food that needs chilling must be kept in a refrigerator, a refrigerating chamber or a cool ventilated place, or kept hot above 63°C. Guidance in Scotland CookSafe says it is recommended practice to run fridges at 5°C or below.

Breaking these hygiene rules is an offence in all four nations. Your council's food officers enforce them, and a conviction can mean a fine or, in the most serious cases, up to two years in prison. For the temperature figures in general, see our danger zone guide.

England and Wales share the FSA's pack for caterers (the FSA pack), Northern Ireland uses Safe Catering, and Scotland uses CookSafe. They agree on the fridge, and differ on the rest.

For a short version of the order to try them in, see the defrosting section of our freezer temperature guide. The rest of this page takes each method in turn, for a kitchen that defrosts every day.

At home, defrosting in the fridge means one chicken overnight. In a kitchen it can mean trays of thighs, cases of prawns, joints for Sunday and bags of stock all at once, in fridges that are already full. That is where it goes wrong: the defrosting tray ends up on the top shelf, or on the worktop, because there was no room.

Plan it like prep

• Guidance in England and Wales The FSA pack asks you to plan ahead so there is enough time and space, and to defrost small amounts. If food often comes out of the fridge still frozen, it suggests defrosting smaller amounts, allowing more time and, if you defrost a lot, more fridge space or a defrosting cabinet.
• Our advice Make "out of the freezer" a job on the prep list for the day before, or two days before for big joints, with a name against it. Pull out only what the next service needs, not the whole case.
• Our advice Freeze in smaller portions. A 1 kg bag defrosts much faster and more evenly than a 5 kg block, and you only take out what you need.

Where in the fridge

• Our advice The bottom shelf, in a deep tray or a lidded container that can hold all the liquid, covered, below and away from anything ready to eat. In a walk-in, a low shelf on the raw side.
• Guidance in Scotland CookSafe says to defrost raw food in the raw food fridge.
• Our advice Do not pack the fridge so tight that air cannot move. A frozen block on a crowded shelf cools everything around it, defrosts slowly itself, and the fridge struggles to hold its temperature.

A fridge or cabinet just for defrosting

Guidance in England and Wales The FSA pack mentions a special defrosting cabinet as an option for a kitchen that defrosts a lot. Guidance in Northern Ireland Safe Catering talks only of extra fridge space. No guidance says you must have a cabinet, and none sets a temperature for one. Our advice A spare fridge kept for raw defrosting is often the simplest answer in a busy kitchen. Treat a cabinet or a defrosting fridge like any other fridge: check and record its temperature.

The fridge temperature

Guidance GOV.UK's guidance for businesses says to set fridges to 5°C or below. Our advice Defrost in a fridge running at 5°C or below, like any other fridge. There is no separate figure for a defrosting fridge. Check it on your opening and closing checks; a fridge that reads above 8°C needs action. Our fridge temperature log guide covers the 8°C and 5°C figures and what to do about a warm reading.

Defrosting raw meat, poultry and fish leaks. The liquid carries the same bacteria as the raw food, and as it thaws there is more of it than you expect.

• Law in all four nations Run-off liquid has to be drained where it could be a risk, and food must be protected from contamination.
• Guidance in England and Wales The FSA pack says to keep meat and poultry separate from other food while it defrosts.
• Guidance in Northern Ireland Safe Catering asks for raw and ready-to-eat food to be kept apart while defrosting, and for meat, poultry and fish to be kept separate and suitably contained.
• Guidance in Scotland CookSafe asks for food being defrosted to be covered and protected by containers or packaging.

Our advice In practice:

• a tray deep enough to hold all the liquid, never a flat sheet or a plate;
• covered with a lid or film, so nothing drips onto it or out of it;
• raw meat and fish below cooked and ready-to-eat food, never above it;
• pour the liquid away down a sink kept for raw food or pot wash, then clean and disinfect the tray;
• do not rinse raw poultry: it spreads germs onto hands, the sink and the worktop;
• wash your hands after handling raw food that is defrosting, and its wrapping.

Our cross-contamination guide covers fridge order and storage in full.

Cold running water is much faster than the fridge because water carries heat into the food far better than air does. Our advice Use it to catch up when planning went wrong, not as a daily method.

• Guidance in England and Wales The FSA pack allows a container under cold running water. For raw meat and poultry, whatever the size, the container has to be sealed, so the water never touches the food and nothing gets onto the sink, the taps or the worktop. If you use a sink, it must be clean and empty before you start, and cleaned and disinfected afterwards.
• Guidance in Northern Ireland Safe Catering allows a lidded container under cold running water. For poultry it adds two things: no splashing, and a sink and surround that are clean and disinfected once you finish.
• Guidance in Scotland CookSafe does not mention running water. If you want to use it, write it into your house rules and ask your council's food team if you are not sure.

Our advice

• The water keeps running. A bowl of still water warms up to the room, and no UK pack describes still water.
• Cold from the tap, never warm.
• The food stays in its sealed bag or a lidded container, so water never touches it and nothing splashes out.
• Nothing else in that sink, and no ready-to-eat food on the drainer, until the sink is cleaned and disinfected.
• Cook it as soon as it has defrosted, or move it into the fridge straight away.

Our kitchen cleaning schedule guide covers cleaning, then disinfecting, a sink.

A microwave defrosts unevenly. The thin edges can start to cook, or sit warm, while the middle is still frozen. That is fine if the food goes straight into the pan, and not if it goes back on the shelf.

• Guidance in England and Wales The FSA pack lists the microwave defrost setting as one of the ways to defrost. It does not say when to cook the food afterwards.
• Guidance in Northern Ireland Safe Catering advises against the microwave unless the food is cooked at once, because the outside can start to warm.
• GOV.UK's advice for home cooks says to use the microwave defrost setting directly before cooking.
• Guidance in Scotland CookSafe does not mention the microwave.

Our advice In every nation, use the microwave only for food you are about to cook, and cook it straight away. Use the defrost setting, small amounts, and turn or separate pieces as they soften. It does not suit large joints, whole birds or big blocks.

Room temperature

Guidance in England and Wales The FSA pack allows room temperature only if necessary, by the maker's instructions and for the shortest time possible, and says the fridge is the ideal. Guidance in Northern Ireland Safe Catering advises against it for your own ready-to-eat dishes that go out with no further cooking or reheating, and notes that while food defrosts fairly fast at room temperature, bacteria can grow if it gets too warm. Guidance in Scotland CookSafe allows a "cool area", and asks you to watch and supervise the time cooked and ready-to-eat food spends at room temperature. Scotland's law also names a cool ventilated place for chilled food. Neither gives a temperature, so set what counts as a cool area in your house rules.

Home cooks get stricter advice: GOV.UK tells them not to defrost a turkey at room temperature.

Our advice We would not defrost raw meat, poultry or fish, or anything ready to eat, at room temperature. The outside sits warm for hours while the middle is still frozen. Where a maker's instructions say room temperature, follow them. A cool area is not a fridge: treat time there as time out of the fridge, kept short and watched.

Hot water

Our advice No UK pack mentions hot or warm water. It is not banned; it is simply missing, and for good reason. Water has to be cold so that it speeds defrosting without letting the outside of the food get too warm. GOV.UK's guidance for businesses says: "Bacteria can grow if defrosting food is kept between 8°C and 63°C." Hot water puts the outside there while the middle stays frozen. Do not use it.

Other shortcuts we see

• a tray left on the pass, by the oven or on top of the dishwasher "for an hour";
• a frozen bag left in an empty sink with no water running;
• food put to defrost on the top shelf, above ready-to-eat food, because the bottom was full;
• a whole case taken out when only half is needed.

Why warm spots matter is in our danger zone guide, on the 8°C to 63°C range.

Big pieces are where defrosting fails most. The outside feels soft long before the middle, or the cavity of a bird, has thawed, and food that is still frozen inside can stay undercooked in the middle when the outside looks done.

How long it takes

No UK guidance for kitchens gives a defrosting time per kilogram. It depends on the size and shape of the piece, the packaging, how full the fridge is and its temperature. The FSA pack asks you to write down how much time you allow. GOV.UK's and Food Standards Scotland's advice for home cooks is to allow about 10 to 12 hours per kilogram in the fridge for a turkey. Our advice Use that only as a rough planning guide for birds and big joints. A flat pack of chicken thighs defrosts far faster than a whole bird of the same weight. Start early, and judge it by checking the food, not by the clock. For a turkey, see defrosting a turkey in our Christmas kitchen guide.

The checks for big pieces

• Our advice If a joint or bird goes under cold running water, it goes in a sealed container (section 5), and it takes longer than you think.
• Our advice Feel the thickest part and, for a bird, inside the cavity. A bird's legs should move freely at the joints.
• Our advice Take any giblets out once they come loose, and cook stuffing separately.
• Our advice After cooking, probe the thickest part. Our cooking temperatures guide has the time and temperature pairs.

• Guidance in England and Wales The FSA pack says to keep bought frozen fish frozen until you are ready to use it. It names mackerel, tuna, anchovies and herring as fish that can cause food poisoning if they are not kept at the right temperature.
• Seafish, the seafood industry body, published a report on thawing seafood in 2008, written mainly for fish processors. It is industry advice, not government guidance. Points from it that are useful in a kitchen: keep fish cold while it thaws and do not leave it unattended; thawed fish spoils as fast as chilled fish that was never frozen; use water only for whole fish or fish that has been headed and gutted, not for cut fillets; and in fish such as mackerel and tuna, histamine forms when the fish gets too warm, and cooking does not remove it.
• Our advice Defrost fish in the fridge, in a tray, covered, and use it soon after. If you use cold running water for whole fish, it stays sealed, like any raw food. Prawns and other shellfish defrost quickly: take out only what the service needs.
• Law in all four nations Fish served raw or almost raw, such as sushi, must have been frozen to kill parasites first, unless it is exempt. Our freezer temperature guide explains the parasite freeze. Our advice That fish will be eaten without cooking, so treat it as ready-to-eat food while it defrosts: in the fridge only, covered, away from raw food. No UK guidance says this in so many words; it follows from how the packs treat ready-to-eat food.

Guidance in England and Wales The FSA pack asks you to check for ice crystals with your hand or a skewer, and that a bird's joints are flexible. Guidance in Northern Ireland Safe Catering adds a probe thermometer, washed and disinfected before and after, with a separate probe for ready-to-eat food. Guidance in Scotland CookSafe asks for food to be defrosted thoroughly before cooking, unless the maker says otherwise.

Our probe check guide covers checking a probe reads true.

Guidance Every pack, and GOV.UK's guidance for businesses, says to defrost food fully before you cook it, unless the pack tells you to cook it from frozen. The FSA pack and Safe Catering also allow a method you have proved to be safe.

• Chips, breaded fish, frozen vegetables and many other bought-in products are made to be cooked from frozen. Follow the instructions on the pack.
• Our advice For anything else, such as your own frozen portions, prove the method first: cook it the same way several times, probe the centre each time, and write the method into your food safety plan. Keep probing it after that.
• Our advice Do not cook large joints or whole birds from frozen unless the maker's instructions say you can.

Once food is out of the freezer, its date is what keeps it safe. A tray with no label is a guess by the next shift.

• Guidance in Northern Ireland Safe Catering says defrosted food not cooked straight away must be date coded and kept in the fridge.
• Guidance in Scotland CookSafe gives no rule for defrosted food. Its stock control rules ask for a suitable use-by date on high-risk food taken out of its packaging or prepared for later.
• Guidance in England and Wales The FSA pack asks for frozen food to be labelled with the date it was frozen.

Our advice Every tray of defrosting food carries:

• what it is;
• the day it left the freezer;
• the date to use it by, worked out by your plan's rule (section 13), and never more than the days it had left on its date when it was frozen.

Law in all four nations Separately, food labelling law has a rule about the word "defrosted". It is about how food is named for sale, mainly packed food, and it leaves out food used as an ingredient. It does not ask a restaurant to write "defrosted" on the dishes it serves. If you sell packed food, including food you pack yourself for direct sale, check with your council's food or trading standards team.

A dated label on a tray in your fridge is stock control, not that rule.

Our stock rotation guide covers labels and day dots.

This is where many websites go wrong, because they mix advice for home cooks with guidance for kitchens. The nations do not agree, and no law sets a time.

Our advice Once no ice is left, you have 24 hours to use it, and less if it had less than a day left on its date when it went into the freezer. In Northern Ireland, follow Safe Catering's one day. Both dates go on the tray label (section 12).

For cooked food that was frozen, and how long cooked food keeps in general, see our food shelf life guide.

Neither "never refreeze" nor "fine if it thawed in the fridge" is what UK guidance tells a kitchen. The answer depends on how far it has defrosted and whether it has been cooked.

• Guidance in England, Wales and Northern Ireland Ice cream, and anything else that has to stay frozen, is used or thrown away once it starts to soften. It cannot go back.
• Law in all four nations The law bans refreezing thawed minced meat and meat preparations, such as raw burgers and sausages. That rule sits in Regulation 853/2004, which is for businesses that need approval, not just registration, such as meat plants. It does not bind a restaurant serving its own customers. A central kitchen supplying meat dishes to other sites may need that approval, and then the rule does bind it: ask your council. Our advice No separate rule is needed for mince in a restaurant: cook any defrosted raw food before it goes back in a freezer, and that covers mince, burgers and sausages too.
• Our advice Reheat cooked food that was frozen once only, until steaming hot. Law in Scotland Reheated food must reach 82°C, with a narrow defence for food whose quality 82°C would ruin. See our reheating guide.

If the freezer itself has failed, our freezer temperature guide sets out how to sort the stock.

Guidance in England and Wales The FSA pack says frozen deliveries should not be left waiting: they go straight into the freezer. Guidance in Northern Ireland Safe Catering expects frozen food to be frozen on arrival and moved into frozen storage at once, and says to reject frozen ready-to-eat food that shows signs of defrosting.

Our advice Packs that are soft or wet have started to defrost. Packs frozen into one solid block, or with a lot of ice inside the bag, may have defrosted and refrozen on the way. Send them back. If you keep a pack that has softened, treat it as defrosting food from that moment: into the fridge, labelled, used quickly. Do not put it back in the freezer raw. Our food delivery checks guide covers frozen delivery temperatures and when to reject.

Inspections cover food handling, preparation and storage, the building and equipment, and how you manage food safety. There is no published checklist for defrosting. An inspector may:

• look at where food is defrosting: on a worktop, in a sink or in standing water, uncovered, or raw food above ready-to-eat food with drip below;
• ask a cook how they defrost a named item, how long they allow and how they know it is fully defrosted;
• compare the answer with your written method;
• check that defrosted food is dated and still within its time, and that the fridge is in range and not overloaded;
• check that a sink used for defrosting is cleaned and disinfected afterwards.

Guidance in England and Wales The FSA pack's defrosting page asks you to write down how you defrost raw meat and poultry, which foods you defrost by which method, and how much time you allow. Guidance in Scotland CookSafe's defrosting step asks you to complete the Weekly Record.

Our advice Put your defrosting method in your plan in a few lines: where you defrost, which foods by which method, how much time you allow, how you check, how long defrosted food keeps, and what you do when it goes wrong. In England and Wales, our free food safety plan builder can help. In Scotland, use your CookSafe house rules; in Northern Ireland, Safe Catering's Defrosting step. Our EHO inspection guide covers the whole visit.

Paper works: a defrosting method in your pack, labels on the trays and a note in the diary when something goes wrong. ChefsRecords is an iPhone app for the daily records. Where it fits around defrosting:

• Fridge checks. The ready-made Opening Checks and Closing Checks have fridge and freezer readings, each saved with who took it and when. Add a line for a fridge you keep for defrosting. A warm reading asks "What was done about it?".
• The Stock Check. The optional Stock Check - Fridges and Freezers has "Anything defrosting is covered and cannot drip onto other food" and "Freezer food wrapped, labelled with what it is and date frozen". Each tick is saved with a name and a time, and you can add your own lines.
• Use-by dates on stock. In the Stock Tracker, log a defrosted tray with its place and its use-by date. Items are listed soonest first, flagged "Use today" on the day and "Do not use" once the date has passed, and the app records who marked each one Used up or Thrown away, and when.
• Cooking and reheating records. Probe the centre of a joint or bird and record it: the reading is saved with the time and the name, and judged against your target. In Scotland, reheating is judged against the 82°C law.
• Frozen deliveries. A frozen delivery reading warmer than -15°C is flagged, with a one-tap answer "Soft or thawed packs rejected, rest accepted".
• When it goes wrong. A Manager or Supervisor can log a Food incident, such as raw meat found defrosting on the worktop, with photos, the action taken and the name of whoever checked the fix.

What it does not do today: there is no defrosting record and no defrost timer. Stock has one date per item, treated as a use-by date, with no "came out of the freezer" or "date frozen" field, and the app does not work out how long defrosted food keeps: you type the date in. It does not print labels. Stock is not in the Inspection Pack. Would you use a defrosting record? Tell us.

Which plan. Checklists and the Stock Tracker come with Standard and Pro, and are open in the 14-day free trial. Temperature records and Food incidents are on every plan.

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Related guides

The freezer temperature guide, the food shelf life guide, the Christmas kitchen guide, the cross-contamination guide, the danger zone guide, the food delivery checks guide, the cooking temperatures guide, the reheating guide and the stock rotation guide.