Coffee Production and Trade

Coffee storage

Storage warehouse - Indonesia

There are a number of precautions that must be taken to keep well dried coffee in good condition and without spoilage or quality loss when it is stored or transported. Special care needs to be given to humidity considerations, storage facility design and location, storage duration, and to the avoidance of rewetting during transportation.

Under no circumstances should fresh cherries be stored before processing and the delay between harvesting and processing should be minimised as far as possible in order to reduce the risk of OTA contamination. It is also important that all containers used in the transportation of fresh cherries and wet parchment are clean, and free of husks and other material known to be highly contaminated with mould.

After processing, dried green beans are usually stored in bags (ideally made from food grade jute or similar material), or in silos, before final milling or hulling prior to export. Only clean, dry bags and silos / bins should be used. The coffee should be covered during transportation, and only loaded / offloaded during dry weather, or under cover. Different coffees (i.e. parchment coffee, dry cherries and/or beans) should not be mixed together for storage.

Bagged green coffee should be stored in well ventilated and leak-proof warehouses, and away from walls on pallets raised off the floor to facilitate ventilation. Once beans are dried to maximum 12.5% moisture content all efforts to prevent re-wetting and airborne moisture absorption must be made (be it from rain, fog, or condensation).

After processing for export (i.e. milling, hulling, grading, sorting and classification), coffee is either transported bagged in containers, or shipped in bulk in containers. In both cases, the critical issue is to avoid rewetting through condensation. Rewetting can be minimised by ensuring that:

• All containers are technically impeccable - i.e. watertight, free of holes and corrosion, with sound seals, dry and odourless;
• Container stuffing takes place under cover, or in dry weather;
• Correct container liners are used according to the shipping method employed (e.g. lined with cardboard, or a container liner);
• Carrier is instructed to 'stow away from heat, cool stow and sun/weather protected' to minimise temperature fluctuations in transit.

Green coffee beans can be stored for a number of years before roasting, though this often has an effect on quality. Although the beans' structure usually prevents them from being spoiled by external agents, biochemical activity in the seed does take place over time, which can result in 'woody' and 'harsh' tastes after roasting.