The discoloration of stored maize as a direct result of heat build-up in the interior of bag stacks, has emerged, during the last decade in sub-Saharan Africa, as a significant food security threat. As a result of such phenomena, internationally called \"stackburn\", both local and imported white and yellow maize cultivars can be affected. Maize may be downgraded in commercial markets or have to be diverted to animal-feed use. When discoloration is severe, food aid agencies attempting to distribute stackburned maize may meet beneficiary resistance or rejection and be forced to dispose of large quantities of deteriorated maize at considerable cost. It is not possible to isolate one primary factor as being responsible for the onset of heating although the presence of excessive levels of foreign material and internal insect infestation may play a part in some cases. The introduction and widespread use of woven polypropylene bags, in substitution of jute bags, appears to have contributed to a greater incidence of stack heating. The constitution of tunnels and chimneys for natural ventilation when building new bagstacks came out as a preventive measure.
Maia, A.; Barros, G.; Mexia, A. Stackburn of stored maize in some sub-Saharan African countries. Bulletin OILB/SROP (2000) 23 (10) 79-85. [IOBC/WPRS Working Group ‘Integrated Protection in Stored Products’. Proceedings of the meeting at Berlin, Germany, 22-24 August, 1999.]