Container Loading and Stowage for Frozen Cargo

The short answer

Frozen cargo is stowed as a solid block, packed tight against the walls and to the edge of the T-bar floor, kept entirely below the red load line, with the airflow path at the rear of the unit left clear. The reefer machine circulates cold air around the outside of that block. It does not push air through it, and it cannot freeze cargo that arrives warm.

That single distinction, block stowage for frozen versus spaced stowage for chilled, explains most of the loading rules below. Get it wrong and you will discharge a container where the door-end pallets are soft, the readings look fine, and nobody can agree who is responsible.

Why stowage decides temperature, not the machine

Buyers of Brazilian frozen chicken, beef and pork often assume the refrigeration unit is doing the work. It is doing less than you think. A reefer unit on a frozen setpoint is a maintenance machine: it removes the heat that leaks in through the walls, doors and floor over a voyage, and it holds an already frozen load at temperature. It has neither the capacity nor the airflow to pull the core of a pallet down.

What protects the cargo is the geometry of the load. If the stow leaves a channel where air can run straight from the discharge end back to the return without touching cargo, the machine will satisfy its own sensors while the boxes furthest from that channel drift upward. For the mechanics of setpoints and sensor placement, see our explainer on reefer container temperatures for frozen meat.

The airflow path you are loading into

Before deciding where boxes go, it helps to picture where the air goes. In a standard marine reefer:

• Cold air is discharged at the bottom of the refrigeration unit at the front of the container.
• It travels the length of the box through the aluminium T-bar floor, the ridged channels you can see and feel underfoot.
• At the door end it rises around and through the cargo.
• It is drawn back in at the top of the unit as return air, which is also where the control sensor usually sits on a frozen setpoint.

Two consequences follow. First, the T-bar channels must stay open along their whole run: nothing loose, no shrink wrap tails, no fallen slip sheets, no crushed carton flaps in the floor grooves. Second, the space above the cargo is the return duct, not spare capacity. Stack into it and you throttle the machine. The red load line marks where that space begins, and it is not advisory. A general overview of the equipment is in what is a reefer container.

Block stowage: the rule for frozen

Frozen cargo is loaded tight. The objective is a single mass with no internal voids, pressed against the side walls and packed to the edge of the T-bar floor, so that air is forced to travel around the periphery rather than finding a path through the middle. Chilled cargo is the opposite case: produce and chilled meat are still respiring or still releasing heat, so they need air moving between the cartons, which is why chilled loads are stowed with deliberate gaps and use vented cartons.

This is also why the distinction between IQF and block frozen product matters at the pallet level as well as the carton level. If you are unfamiliar with the difference, see IQF versus block frozen chicken.

A working loading sequence

Before the container arrives

1. Confirm the product is already at carrying temperature in the blast freezer or cold store. Pull core readings, not surface readings, and keep the record.
2. Inspect the empty container: clean, dry, no odours, doors and gaskets sound, T-bar floor clear, drain holes clear, and the unit having passed a pre-trip inspection.
3. Decide the pre-cooling question deliberately. Running a frozen setpoint on an empty container at a warm, humid dock draws moisture in and condenses it on the cold interior, which soaks cartons and weakens them. Where the plant loads through a sealed cold tunnel or dock shelter, pre-cooling is straightforward and sensible. Where it loads on an open apron, many Brazilian plants will instead keep the unit off during stuffing and start it the moment the doors close, to avoid soaking the cargo.

During stuffing

1. Load fast. Every minute the doors are open in a Brazilian summer is heat entering the box. Stage the full load before you start.
2. Build tight to the side walls and front bulkhead, leaving the unit's discharge area itself unobstructed.
3. Keep every carton below the red load line, including the highest point of any pallet that has settled unevenly.
4. Fill or bridge voids with dunnage, airbags or void fillers so the block cannot shift and air cannot shortcut through it.
5. Leave the small clear gap at the door end that the container is designed for, and never stack against the doors in a way that will collapse outward on opening.

Closing out

1. Photograph the finished stow from the door, with the red line and the door-end face visible.
2. Record the setpoint, the seal number and the time the doors closed.
3. Confirm the unit has started and is pulling to setpoint before the box leaves the plant.

A photograph of the finished stow, taken from the doors before sealing, is the single cheapest piece of evidence in a frozen meat claim. It settles arguments about voids, load line and door-end packing that no data logger can answer.

Weight, distribution and securing

The reference standard here is the IMO, ILO and UNECE Code of Practice for Packing of Cargo Transport Units, usually called the CTU Code. It is not legally binding in itself, but carriers write it into contracts and insurers treat it as the standard of care, so a stow that ignores it is a weak position in a dispute.

Practically, for frozen meat the points that bite are:

• Even distribution. Weight should be spread along the length of the container, not concentrated at one end. Dense products such as boneless beef fill out a container's weight limit long before its volume.
• The real ceiling is the road limit. A 40 foot high cube reefer offers a large nominal payload, but the binding constraint is almost always the road weight limit at origin or destination, not the container plate. Confirm the limit for the destination country before fixing the loading plan.
• Securing. A true block stow largely secures itself, but any partial load, mixed load or void must be blocked and braced so it cannot move in transit.

Pallets or floor loaded

Both are used for Brazilian frozen meat and the choice is commercial rather than technical. Floor loading gets more cartons into the box and suits leg quarters, wings and bulk cuts going to markets where labour for manual discharge is available. Palletised loads discharge far faster, protect cartons better, and suit buyers feeding modern distribution centres. Palletising costs you cartons per container, and the pallets must still be loaded tight and to the T-bar edge.

Whichever you choose, specify it on the purchase order. Discovering at discharge that a container is floor loaded when the cold store expected pallets is a costly and avoidable surprise. Packaging conventions by product are covered in frozen pork packaging and cold chain.

Common stowage mistakes on frozen meat shipments

• Stacking above the red load line to squeeze in a final tier.
• Leaving a hollow channel down the centre of the load, which lets air short-circuit to the return.
• Loose plastic, strapping or broken cartons blocking the T-bar floor channels.
• Loading product not yet at carrying temperature and expecting the unit to finish the job.
• Pre-cooling an empty container on an open dock in humid conditions, then loading into condensation.
• Leaving unsecured voids in a partial load, so the block shifts in transit.

What to agree with your supplier in writing

Stowage is a contractual matter, not only an operational one. Before the first container ships, agree the stow pattern, whether the load is palletised or floor loaded, the pre-cooling approach at that specific plant, the core temperature required before stuffing, the photographic record to be taken at sealing, and who bears the cost if the stow is found non-compliant at discharge. Brazil's export meat sector is large and well regulated, as the Brazilian Animal Protein Association documents, but stowage discipline still varies plant by plant and is worth confirming rather than assuming.

Brazil Prime Foods Export ships frozen chicken, beef and pork from SIF registered plants and will confirm the stowage plan, palletisation and loading records for your market before shipment. See our frozen chicken, frozen beef and frozen pork pages, review our certifications, or request a quote. For the wider picture, start with our guide to cold chain logistics for frozen food exports and the companion piece on Brazilian ports and transit times.