Ask how bananas are shipped and the answer is usually “thirteen degrees, carefully controlled”. That is not a setting; it is a slogan with a number in it.
The reefer container settings for bananas are a short list of separate fields — setpoint, fresh air exchange, humidity mode, atmosphere and stowage limit — each entered on its own, and each with its own way of ruining a container. Here is what gets typed in, what each figure is measured against, and what goes wrong when it is not.
Reefer container settings for bananas: the baseline
| Setting | Value | Note |
|---|---|---|
| Carrying temperature | 13.2 – 13.5 °C | On delivery air |
| Carrying temperature under CA | 14.0 – 14.4 °C | Higher than normal air |
| Relative humidity | 85 – 95 % | Humidity control set to off |
| Fresh air exchange | 25 – 30 m³/h | Closed during pull-down |
| Internal air circulation | 60 – 80 changes/hour | Continuous |
| CO2 ceiling, normal air | 0.1 – 0.2 vol % | Held by ventilation alone |
| Controlled atmosphere | 3 % O2, 4 – 5 % CO2 | Vents closed |
| Practical transit | ~40 days normal air, ~45 days CA | Carrier figures |
These are industry starting points, not house practice; where your carrier’s voyage instructions differ, theirs govern. But settings only protect what you loaded. They do not improve fruit outside the length and grade you contracted, which our guide to Cavendish banana grades and sizes covers.
The setpoint is delivery air, not return air
A reefer measures air twice: the air it delivers under the T-floor, and the air returning to the machinery after passing through the cargo. For chilled cargo the unit controls on delivery air, and delivery air is what a carrier can actually guarantee.
This changes how you read a data logger. The return air sensor sits close to the machinery, so a defrost cycle shows up there as a spike long before it means anything to the fruit. Spikes on a return air trace are normal; drift on a delivery air trace is not. Place your own recorder near the delivery air at the machinery end, not somewhere convenient in the middle of the stow.
Do not pre-cool the container
This one surprises people, because it sounds like diligence. Reefer carriage guidance is explicit: containers should not be pre-cooled before loading except in exceptional circumstances, because warm humid air enters during stuffing and condenses on cold surfaces. Wet cartons lose stacking strength, and free water on the fruit invites crown rot.
What has to be cold is the fruit, not the box. Field heat comes out at the packhouse, before stuffing. At loading, pulp temperature should not exceed ambient air; a reading above 30 °C warns that the fruit may already have gone climacteric — started to ripen — and no setpoint reverses that.
Humidity control stays off
Bananas want 85 to 95 % relative humidity, and the correct setting is nonetheless humidity control: off. Not a contradiction.
The fruit respires and gives off water, and inside a polyethylene-lined carton the microclimate reaches the right humidity by itself. Switching humidity control on tells the unit to manage toward a target, which in practice means dehumidifying — drying the fruit and softening the cartons for no benefit. Off is the correct setting, not an omission.
Fresh air exchange, and what CO2 is telling you
A container of bananas is a closed box full of something breathing. At 12.5 °C a green banana gives off roughly 18.5 mg of CO2 per kilogram per hour. A finger that has started to turn gives off about 62 mg — more than three times as much, along with the heat that comes with it.
That is why a single pallet of advanced fruit is not a small problem: it raises CO2, warms its own corner of the stow, and releases ethylene into a box full of fruit that is highly sensitive to it. Bananas are moderate producers of ethylene at 1 to 10 µl/kg·h, which is also why they never travel with apples, pears or anything else already ripening.
Fresh air exchange holds that in check: 25 to 30 m³/h for a full container, vent closed during the initial pull-down and opened once the load is at temperature. On normal air, CO2 should sit around 0.1 to 0.2 vol %. One safety note belongs in every set of instructions: a container that has carried bananas can hold enough CO2, and little enough oxygen, to be dangerous. Ventilate and gas-test before anyone steps inside.
Stowage is the setting you cannot type in
Every figure above assumes air can move. Cargo must never be stacked above the red load line marked inside the container: that gap is the return air path, and blocking it is the commonest way a correctly programmed container still fails.
When circulation is blocked, cooling becomes uneven and the cargo furthest from the delivery air ripens first. It arrives as a claim even though the setpoint held all voyage, and the logger shows a clean trace — because the sensor was never near the warm part of the stow. Leave clearance around the stow and treat the red line as a hard limit.
Controlled atmosphere: about five extra days
Controlled atmosphere pulls oxygen down to around 3 % and holds CO2 at 4 to 5 % with the vents closed, slowing respiration and ethylene production. The setpoint goes higher, 14.0 to 14.4 °C, and carriers quote up to 45 days transit against roughly 40 on normal air.
Whether that is worth paying for depends on the route. On long-haul voyages it can be the difference between a viable lane and an impossible one. For fruit moving from Vietnam into southern China, Malaysia, Singapore or the Gulf, the voyage is short enough that CA is rarely the deciding factor — proximity already does that work. On those lanes, harvest maturity and loading discipline repay more than atmosphere control.
Working with Dragon Hub
Dragon Hub packs and exports Cavendish bananas to supermarket and wholesale buyers across Asia and the Middle East. We ship to the regime the buyer states rather than to a house default, we record the settings entered, and we say so when a route and a requested maturity do not fit each other — before the container is sealed, not after. Bananas sit alongside mango, pomelo, seedless lime and dragon fruit in our product range, and the full specification is on the Cavendish banana page. Send your destination, transit time and your carrier’s proposed settings, and you will get a specific answer.
Frequently asked questions
What temperature should a reefer container be set to for bananas?
Between 13.2 and 13.5 °C on normal air, and 14.0 to 14.4 °C under controlled atmosphere, controlled on delivery air rather than return air. Below about 13 °C the fruit suffers chilling injury and will not ripen properly afterwards; above about 15 °C it ripens in transit.
Should a container be pre-cooled before loading bananas?
No, other than in exceptional circumstances. Pre-cooling the empty container makes warm humid air condense on cold surfaces during stuffing, weakening cartons and wetting the fruit. Remove field heat from the fruit at the packhouse instead, so pulp temperature at loading is no higher than ambient air.
Why is humidity control switched off for banana shipments?
Because the fruit maintains its own humidity. Bananas respire inside polyethylene-lined cartons and the microclimate settles at the 85 to 95 % they need. Active control would dehumidify toward a target, drying the fruit and softening the cartons. Off is the correct setting, not an omission.
What causes under-peel discolouration in shipped bananas?
It is generally associated with carriage at too low a temperature. Dark strands appear beneath the skin, and the fruit often looks acceptable when the doors open, failing days later in the ripening room. Being temperature damage rather than handling damage, it usually affects a large share of the container.
Is controlled atmosphere worth it for bananas from Vietnam?
Usually not on regional lanes. CA buys roughly five extra days, 45 against 40, which matters on long-haul routes. Voyages from Vietnam to southern China, Malaysia, Singapore or the Gulf are short enough that harvest maturity and correct stowage deliver more than atmosphere control does.
Sources
- Transport Information Service (GDV) — Bananas: temperature, humidity, circulation, CO2 and ethylene data
- West of England P&I — The Carriage of Reefer Containers: delivery air, pre-cooling, red load line
- Hapag-Lloyd — Controlled Atmosphere: CA transit times
