What is cold chain transport? Temperature bands

What the cold chain is

The cold chain is keeping a product within a specific temperature range, without interruption, from production through to final delivery. The chain metaphor is apt: if one link breaks, the fact that the others are intact changes nothing.

The critical point is this: what spoils a product is usually not the transport itself, but the stops along the way. Half an hour at the loading bay, a night spent in customs, a door left open during transfer. Without a log, none of this is noticed, and the problem only surfaces on arrival — which is when the dispute over responsibility begins.

Temperature bands

Four bands are used in practice:

Band	Typical range	Use
Frozen	−18 °C and below	Frozen food, meat, seafood
Chilled	0 / +4 °C	Fresh food, dairy, meat
Cool	+2 / +8 °C	Pharmaceuticals, vaccines, biological products
Controlled room temperature	+15 / +25 °C	Certain medicines, cosmetics, sensitive chemicals

The band is chosen according to the product’s own requirements and is confirmed in writing before loading. A verbal understanding protects neither party in the event of damage.

Pre-cooling

This is the most commonly skipped step, and the most costly one to get wrong.

A refrigerated unit or reefer container is designed to keep a load cold, not to cool it down. If the body has not been brought down to the target temperature while empty, the warm air inside comes into contact with the product the moment it is loaded. By the time the unit tries to compensate, the chain has already broken.

The fix: make pre-cooling part of the loading instructions, and record that the body has reached the target temperature before loading.

Equipment

Refrigerated vehicle — for road transport. The unit is powered either by the engine or by an independent power source.

Reefer container — for sea and intermodal transport. It needs a power supply on the vessel, at the terminal and during the road leg; any break in supply is a direct deviation. Its interior volume is smaller than a standard container’s because of the refrigeration unit and the thick insulation.

Temperature-controlled air cargo — for short, high-value shipments; an actively powered container or passive thermal packaging is used.

Ventilation is a separate matter

Even at the right temperature, a load can still spoil. Fresh fruit and vegetables respire: they consume oxygen and produce carbon dioxide and ethylene. A load carried with ventilation closed can be damaged even at the target temperature.

Ventilation and humidity settings are product-specific and must be confirmed in writing before loading.

Logging and responsibility

A data logger is placed on every shipment; temperature is recorded at set intervals and the report handed over on arrival. On reefer containers, the unit’s own log is also captured.

The log serves two functions. First, it provides evidence for the customer’s own quality system. Second — and operationally more important — it shows where a deviation occurred, if one did. Knowing where it happened is the only way to place responsibility with the right party.

Common mistakes

Skipping pre-cooling. The most common, and the earliest, point where the chain breaks.

Not confirming the temperature range in writing. A verbal understanding has no evidentiary value in the event of damage.

Carrying sensitive products on a multi-stop route. The door opens at every stop. A full-load vehicle should be preferred for sensitive loads.

Treating customs time as outside the chain. If declaration preparation is delayed, the load waits. Waiting in the cold chain is not the same as waiting with dry cargo — which is why document preparation is planned around loading rather than arrival.