How to store white sugar: humidity, temperature and shelf life.

The numbers

All of these come from the white sugar entry in the Transport Information Service of the GDV, the German insurance association, which is written for the people who insure cargo. Its advice on temperature is simple: no lower limit, 25°C at the top, and no big swings.

Dry sugar going in is half the job

The GDV also says only matured sugar with a water content below 0.05% should be loaded, or below 0.03% for longer voyages, and that above 0.05% the sucrose can start to break down. Brazil’s standard caps moisture at 0.05% for refinado granulado, the class ICUMSA 45 falls under, which matches that loading threshold. The ICE white sugar contract is slightly looser, at 0.06% when the sugar is delivered to the vessel. So read the moisture line on the certificate of analysis as a storage figure as well as a quality one. If it is at the ceiling and the voyage is long, ask about it.

The bag does most of the work

The ICE white sugar contract requires new, sound polypropylene bags of at least 50 kg net, each with a single new polythene liner. The GDV says white sugar mostly travels in jute or woven plastic bags with a plastic inner bag, and that because the lining stops water vapour getting in, bagged white sugar doesn’t normally need ventilating in the hold. A torn or wet bag loses that protection, so count and photograph damaged bags at discharge.

In a container

A closed container makes its own weather. The GDV’s container handbook explains that large amounts of sweat in a closed container always come from the cargo or its packaging, or a wooden container floor: high temperatures drive water vapour out of hygroscopic goods, and it condenses on walls and roof cooled overnight. Sugar is hygroscopic. Here is what I’d do about it:

• stuff dry sugar into a container that is clean, dry and free of smells;
• don’t load in the rain, and don’t put wet pallets or dunnage in with it;
• keep it away from heat sources;
• unload promptly at destination rather than leave the box standing in the sun.

More on container shipments in buying Brazilian sugar by the container.

In your warehouse

• Aim for 55 to 65% relative humidity and below about 25°C. A cheap hygrometer tells you more than the weather forecast.
• Stack it on pallets, off the floor and away from outside walls.
• Keep it away from anything that smells. The GDV calls sugar “extremely sensitive” to foreign odours.
• Keep the store clean and dry. Seawater, rain and condensation can lead to mould and fermentation.
• Use the oldest stock first.

Does sugar need an expiry date?

Not under EU law. The EU food information regulation lists “solid sugar” among the foods that don’t need a date of minimum durability, alongside salt and vinegar. Other countries set their own labelling rules, and yours may want a date on the pack. Check before you contract, and ask then whether the bags can carry one.

If it arrives caked or damp

Hard lumps or wet bags at discharge can be a claim under your contract, and you will need proof of when the damage happened. Have the independent inspector record the condition before the cargo leaves the port, photograph the bags, and note the humidity and temperature where it was stored. See what protects you if sugar arrives off-spec.