Impact of threshing moisture content, threshing methods, and storage structures on storability of maize grain

Inefficient post-harvest management, including threshing methods and storage structures in developing countries, results in considerable nutritional loss of maize grain. This study evaluates the effects of maize grain threshing conditions, methods, and storage structures on nutritional content of maize and mold growth on it. Freshly harvested maize grain was threshed using two techniques (manual and mechanical) at two moisture levels (17% and 23%). The threshed grains were then dried to a safe storage moisture level (13% w.b.) using a solar bubble dryer. The dried maize grains were stored in five types of storage bags for six months. Nutritional loss, color changes, and mold growth were measured at three-month intervals during the storage period. Data analysis conducted using Minitab revealed that the oil content, starch content, and mold growth were significantly (P < 0.05) influenced by storage bag type, grain moisture content during threshing, and threshing techniques. Maize threshed at 17% moisture content retained higher fat and protein levels and exhibited lower mold growth than grain threshed at 23% moisture content. The type of storage bag also significantly affected the starch content of the maize grain. After six months of storage in woven polypropylene bags, starch content decreased by 2.79%, oil content by 6.72%, while protein content increased by 0.44%, and moisture content rose by 12.34%. Hermetic storage bags demonstrated minimal nutritional changes and mold growth. Promoting the use of mechanical threshers at optimal grain moisture levels and hermetic storage bags is essential for smallholder farmers to maintain the quality and safety of their maize grain, reducing post-harvest losses and ensuring food security.