Stackburn in maize is heat damage characterized by a brown discoloration of the grain resulting from heat build-up in the interior of stacks held in commercial storage in sub-Saharan Africa. Affected maize may be downgraded in commercial markets or have to be diverted for animal-feed use. Where 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 (up to GBP 23 million during 1993 in southern Africa). Heat build is linked to restricted airflow resulting from the use of woven polypropylene sacks. Building stacks with internal gaps to allow air flow and/or a return to jute sacks prevents stackburn, with some slight loss in plinth capacity.