How does the cold chain work, and what happens when it breaks?

By Muhamed Selmani, Founder17 August 2026

A cold chain is unbroken temperature control from production to service, judged on the temperature of the food rather than the air around it. In England, assimilated Regulation (EC) No 852/2004 requires that it is not interrupted, and the Food Safety and Hygiene (England) Regulations 2013 make it an offence to keep food that supports pathogen growth above 8°C. A break is a judgement on time and temperature, made by the food business receiving the load.

The cold chain is a chain of custody with a temperature attached

Ask what a cold chain is and you get a description of a fridge. That is the least interesting part of it. The chain is the sequence of hands a load passes through — the production kitchen, the loading bay, the vehicle, the goods-in door, your own fridge — and the temperature is only the thing being conserved across each handover.

Which puts the exposure at the joins rather than in the miles between them: a stack staged on a bay while a yard gate is found, a door held open through a paperwork argument, a load that left warm and was never going to catch up. Each join is a contractual event as well as a physical one — somebody becomes answerable and somebody stops being.

What temperature chilled food must travel at

There is no single blanket figure in English law. Three different things get quoted as the number, and they are not interchangeable.

The general duty comes from assimilated Regulation (EC) No 852/2004: food likely to support the growth of pathogens or the formation of toxins is not kept at a temperature that risks health, and the cold chain is not to be interrupted. It is an outcome duty, and it names no number.

Scotland, Wales and Northern Ireland run their own instruments; what follows is the England position, which governs a London route.

The numbers that sit on top of that duty

The England figure — the Food Safety and Hygiene (England) Regulations 2013 make it an offence to keep food that supports pathogen growth above 8°C, subject to exemptions. It attaches to the food rather than the air, and premises, under the Food Safety Act 1990, includes a vehicle.
The animal-origin figures — assimilated Regulation (EC) No 853/2004 sets lower temperatures for products in its scope, including 7°C for meat carcases and 3°C for offal.
What an operation runs at — colder than the ceiling on purpose. Industry practice commonly works to 5°C or below, and the gap is headroom for door openings and load transfer.

Chilled and frozen are two different jobs

For frozen the number is firmer. The Quick-frozen Foodstuffs (England) Regulations 2007 require quick-frozen foodstuffs to be held at −18°C or colder, and permit a brief upward fluctuation during transport, including local distribution, to no warmer than −15°C. Read the category: the rule attaches to quick-frozen foodstuffs as legally defined, not to everything a kitchen calls frozen.

Operationally they fail in opposite ways. Chilled fails gradually — a load drifts, nothing looks wrong at the door, and the cost lands days later as shortened life. Frozen fails abruptly, and a partial thaw is not reversed by putting the case back in the freezer.

So the exposure sits in different places. Chilled is daily and sequenced around a service, which puts the risk in the sequence and the door time. Frozen is bulk and infrequent, and the receiving end decides it — freezer space, and somebody there to take it — so one failed delivery can be a fortnight of stock.

How a chilled delivery actually runs

A chilled round is planned backwards from the temperature rather than forwards from the collection. The load leaves at temperature, because a refrigerated body is built to hold one rather than pull one down: a warm load put into a cold vehicle stays warm for a long time.

Then the sequence, which is where the headroom is spent. Each opening of the door costs some of it, so a round with 12 drops is a different thermal problem from a round with 3, and the site at the end carries the accumulated cost of the ones before it.

At the door, the transfer is the exposed minute. Receiving is the other half: a check made at goods-in in the first minutes, rather than after the driver has gone, is what turns a delivery into a record you can rely on.

Temperature monitoring, and what turns it into an audit trail

Monitored is one word covering three records that prove different things, and being precise about which one you are offered is most of the value here.

Air is not food, and the difference is not academic: a body at 4°C with a case of warm product in it reads perfectly on the vehicle log. If a provider says the load is monitored, the question that separates the answers is what the probe is in — and then who takes the reading, on what device, and how long it is kept.

An audit trail is the next thing along — the ability to reconstruct one delivery, months later, without asking anybody to remember it. Pick a drop from 9 weeks ago and ask what the product temperature was at handover and who accepted it. If that takes a week, the trail exists on paper rather than in practice.

Three records, three different proofs

Vehicle air temperature, logged continuously by a probe in the body. Proves the vehicle was cold. Does not prove the food was.
Product temperature at handover, taken of the load itself and recorded against the drop. Proves the food at the one moment responsibility moves.
A logger travelling inside the load, read at the far end. Proves the journey rather than the endpoints — the only one that shows a spike sitting between two clean readings.

What a cold chain audit trail has to contain

Retention is a decision rather than a default: pick a period that outlasts the life of what you move and the notice period of your agreement, then put it in the contract. And a trail is only worth what it can be tested with — ask a provider for one week of real records from a route they already run, with the client's name removed.

What left, from where, at what time, and at what temperature.
Which vehicle and which driver — the same question your own traceability exercise will ask.
The temperature record across the journey, not only at the two ends.
What arrived, when, at what temperature, and who accepted it.
Any exception — a late drop, a reading out of range, a refused pallet — and the decision taken.
Where the record is held, who can pull it, and how long it survives.

A cold chain break: what to do, in order

A break is not automatically a write-off. The general duty permits limited periods outside temperature control for the practicalities of transport and handling, provided there is no risk to health. What decides the outcome is time and temperature together, against that particular product — and the judgement belongs to the food business receiving the load, under its own procedures, not the carrier's.

So the order is: preserve the evidence, decide, then record what the decision cost. Afterwards, find out which join failed — until you know that, the corrective action is a conversation rather than a change.

The first hour

Isolate the load and label it. Do not put it into stock, and do not destroy it — the decision has not been made.
Take the temperature of the product, not the air, and write down the time you took it.
Establish how long it was out of range from the transport record rather than from memory.
Ask your own procedures what that product tolerates. A sealed case and an open tray are not the same decision.
Decide — accept, shorten the life, quarantine or reject — and have a named person make it.
Tell the carrier and the supplier in writing the same day, with the readings and the times.
Record the decision and what it cost. That is the line easiest to skip, and the one that funds fixing the route.

How Fleetable runs a chilled route

Everything above is a set of questions to put to a carrier, and they apply to this one. Fleetable moves chilled, frozen and ambient loads across London on contract rather than by the job — a set driver, a named backup behind them, and a rate per mile with every cost shown. No accreditation is held today, and accreditations are added as contracts require them.

Put the temperature questions above to Fleetable the way you would put them to anyone else, and judge the answers on the same terms. Then test the whole of it on one route, run in parallel with your current provider, with nothing switched until it works.

Continue reading

FAQ

Questions, answered.

Is 8°C the temperature my chilled deliveries should run at?

It is a legal ceiling, not a target. The offence is keeping food that supports pathogen growth above it, so an operation that runs at 8°C has no headroom for a door opening. Industry practice commonly works to 5°C or below, and products of animal origin under assimilated Regulation (EC) No 853/2004 carry their own lower figures. Set the operating temperature against the product and write it into the contract.

Does a temperature reading at the door prove the cold chain held?

It proves the endpoints. Two clean readings can sit either side of an hour out of range, and neither will show it. A logger travelling inside the load is what evidences the middle of the journey — worth requiring on the routes where the load value or the shelf life justifies it, rather than on all of them.

How long should temperature records be kept?

No period is quoted here, because the answer depends on what you move and what your contract says. Set it against the life of the product and the notice period of the agreement, then write it into the contract along with how fast a record can be retrieved. A retention rule nobody has tested is not a retention rule.

Who decides whether a load that has been out of range is rejected?

The food business receiving it, under its own procedures based on HACCP principles. The carrier supplies the record; the decision and its consequences sit with the operator whose name is on the food. Agree in advance who is called, who decides and inside what time, because that conversation goes badly when it is being invented at the goods-in door.

Start

Not a sales call. A diagnosis.

Book a capacity review Send your routes