After lifting, the crop is held at around 30 °C and high humidity for several days. Two things happen. The skin sets, hardening the surface so it resists the scuffing that handling inevitably causes. And the wounds from harvesting heal over, closing the entry points that rot would otherwise use.
Curing also converts some starch to sugar, which is why a cured sweet potato eats better than a freshly lifted one. Commercially, though, the reason to insist on it is shelf life: an uncured crop loses moisture faster, scuffs on the way to the port and arrives looking tired even when the cold chain was perfect.
Quality in April depends on how well the packhouse cured the crop the previous autumn. This is the question to ask a supplier that most buyers never ask.
13 to 15 °C with humidity around 85 to 90 per cent is the working window. The lower end slows respiration and extends life; the upper end is safer against cold spots in a badly loaded container. Where you sit in that range should depend on transit length and how confident you are in the pallet build.
Humidity matters more than most buyers realise. Sweet potato loses weight through the skin, and a dry container arrives lighter than it left — shrinkage you paid for. Specify the humidity, not just the temperature.
A reefer cools by moving air, not by contact. If the pallets are built so tight that air cannot pass through the stack, the set point on the controller describes the air leaving the unit, not the temperature of the fruit in the middle of the load. Vent holes in the cartons need to align between layers, and the load needs to leave the channels the container was designed around.
This is why a container can show a perfect temperature trace and still arrive with a warm core.
Ask for the temperature record for the voyage as a matter of course, not only when something goes wrong. It should show the set point, the supply and return air temperatures and the full time series from loading to discharge. Two details are worth checking every time: the pull-down at the start, which shows whether the crop went in warm, and any gaps, which usually mean the unit was off during a transfer.
A supplier who cannot produce the trace is telling you something. Make it a contractual deliverable alongside the phytosanitary certificate and the packing list.
