Quick-frozen food sold in the European Union is expected to be held at minus eighteen degrees Celsius or colder. The framework directive on quick-frozen foodstuffs allows brief upward fluctuations during transport and local distribution, and sets tighter expectations for the storage phase than for the retail display cabinet. The practical consequence is that a recorder trace showing a short spike is not automatically a rejection, and a recorder trace showing a long plateau at minus twelve is not automatically defensible. You need a procedure that tells the two apart.
What has to be recorded
Commission Regulation (EC) No 37/2005 requires the air temperature in means of transport, warehousing and storage of quick-frozen foodstuffs to be monitored with suitable recording instruments at frequent and regular intervals. The dated records have to be kept for at least one year, or longer where the nature and shelf life of the product require it.
The instruments themselves are covered by European standards:
- EN 12830 for the recorders used in the transport, storage and distribution of chilled, frozen, deep-frozen and quick-frozen food.
- EN 13485 for the thermometers used to measure air and product temperature.
- EN 13486 for the periodic verification of those instruments.
An auditor will ask for the calibration certificate before looking at the chart. A trace from an uncalibrated device is not evidence.
What a recorder actually measures
Almost every trailer or container recorder measures return air, and often supply air as well. Neither is product temperature.
- Return air responds within minutes to a door opening; a frozen pallet core moves over hours.
- A supply-air trace looks calmer than reality because it reads the air the unit has just chilled.
- Product core temperature is measured with a probe pushed between two cartons in the middle of a pallet, held until the reading stabilises. Surface readings on the outer carton overstate the problem.
This is why a five-minute spike to minus eight on the return-air trace during a delivery stop does not mean the product went to minus eight. It also means that a slow drift up to minus fourteen over eighteen hours almost certainly did reach the product.
Reading an excursion
Three numbers describe any excursion: how high, how long, and where in the journey.
| Pattern | Likely cause | Usual product impact |
|---|---|---|
| Short sharp spikes at intervals | Door openings on a multi-drop run | Surface only; check top and door-end pallets |
| Step up that never recovers | Unit failure or set point changed | Treat as a real break; assess by duration |
| Sawtooth around the set point | Normal defrost cycling | None |
| Slow warm drift from loading onward | Trailer not pre-cooled, or product loaded warm | Real; the whole load is suspect |
| Flat line, no variation at all | Recorder failure or a sensor out of the airflow | No evidence either way; escalate |
A flat line is the one most often mistaken for good news. A working recorder in a working reefer always shows the defrost sawtooth. A perfectly straight trace usually means the probe fell out of the airflow or the device stopped logging.
The quality question behind the temperature question
Warming does not make frozen fruit unsafe in the way that warming chilled meat does, provided the product does not thaw. What it does is destroy quality, and quality is what the contract sells.
- Recrystallisation. Each warming and re-cooling cycle grows the ice crystals inside the fruit. Larger crystals rupture more cell walls, so the fruit drips more on thawing and loses shape.
- Clumping. In an IQF pack, partial surface melting followed by refreezing welds the individual pieces into blocks. The buyer bought free-flowing fruit and receives something they cannot dose on a line.
- Freezer burn and desiccation on long exposures.
- Colour and vitamin loss over time, accelerated at higher storage temperatures.
Clumping is the giveaway on delivery. If a bag that should pour is a solid lump, something warmed it, whatever the chart says.
A decision procedure for the receiving dock
- Before breaking the seal, photograph the seal, the seal number and the recorder display.
- Download the full trace, not a screenshot of the current reading. Save the raw file.
- Take at least three product core readings: front, middle and rear of the load, mid-pallet.
- Open one bag from a rear pallet and check for clumping and ice crystals inside the bag.
- Classify: no excursion, surface excursion, or bulk excursion.
- For anything above surface level, place the load on hold rather than rejecting it at the gate. A hold preserves your options; a refused delivery on the CMR starts an argument you may not need.
- Record a reservation on the consignment note at the moment of delivery. Under the CMR Convention, damage that is not apparent has to be notified in writing within a short period after delivery, and a delivery accepted without reservation creates a presumption against the claimant.
- Notify the seller and the carrier in writing the same day, with the trace attached.
- Agree the disposition: accept, accept with a concession, downgrade to an industrial specification, or reject.
Put the whole of this procedure into the contract before the first load. An excursion clause negotiated after an excursion is negotiated from a bad position by both sides.
Contract wording that works
- The maximum product temperature at loading and at delivery, stated as a core temperature.
- The recording obligation: device type, logging interval, and that the raw file is provided on request.
- Who may take the confirming reading and with what instrument.
- Severity bands with defined outcomes, rather than a single pass or fail.
- A time limit for notification and for the joint review.
- The evidential status of the trace: it is evidence, not a verdict.
Storage at the destination
The chain does not end at the gate. A cold store that runs at minus sixteen because the door curtains are broken will undo a perfect transport record over a fortnight. Ask the destination store for its own recording regime, and put the store’s temperature obligations into the storage contract with the same specificity.
Related: what to do when a logger shows a break, who owns temperature risk under FCA, and the Incoterms 2020 guide.