Frozen foods are commonly shipped at minus 18 °C or colder. That is the widely used reference point for frozen food, and many shippers set the reefer a few degrees colder to give a margin.
The exact setting should follow your product spec and the importing market's rules. Write it into the contract and the booking, so the plant, the forwarder and the shipping line all work to the same number.
Why minus 18 °C
At around minus 18 °C, most microbial growth stops and quality loss slows enough for long storage. Food safety guidance and many national rules for quick-frozen food use this figure as the standard storage temperature. The EU's rules on quick-frozen foods, for example, use minus 18 °C as the reference, with only brief, limited rises allowed during transport and distribution.
Rules and tolerances differ by country and change over time. Check the current requirement with the food authority in your market, and ask your customers whether they set a colder limit.
Setting the reefer
- State the set point in the contract and on the booking with the shipping line.
- Use Celsius clearly, and check the unit on the booking form.
- Set the air vents closed for frozen cargo, unless the line advises otherwise.
- Ask for a pre-trip inspection of the reefer before it reaches the plant.
- Record the set point on the loading report and the bill of lading if possible.
The product must already be frozen
A reefer is built to hold temperature, not to freeze warm cargo. If product is loaded above the set point, the unit may struggle to pull it down, and outer cartons may stay warm for days. The product should be at or below the target temperature, through to the core, before it leaves the cold store.
Ask the plant to record core temperatures of sample cartons at loading, using a calibrated probe thermometer. Load quickly from a cold store or covered dock, and do not leave pallets waiting in the sun. How to monitor a reefer's temperature covers the checks during transit.
Products with different needs
Some products are shipped colder than minus 18 °C, such as ice cream and some seafood, often at minus 20 °C to minus 25 °C or below. Chilled products, usually held just above freezing, are a separate category and must not share a reefer with frozen goods. If you mix frozen items, they must all suit one set point, as covered in mixing frozen products in one reefer.
How we help
Our inspectors check cold store records, measure core temperatures of your cartons and confirm the reefer set point before the doors close. You receive the readings and photos the same day. Ask for a free sourcing review.