Effect of Threshing and Storage Conditions on Mold Contamination of Stored Maize Grain (Zea mays L.)

Although maize is a staple crop in Ethiopia, an inefficient postharvest management system causes significant postharvest loss of it. The purpose of this study was to study the effect of threshing and storage conditions on mold contamination of maize grain during storage. Freshly harvested maize grain with BH-540 variety was used for the study. Maize at two different moisture content, 17 ± 0.5, and 23 ± 0.5%, was threshed by hand and mechanical threshing methods and then dried to safe storage moisture (13 ± 0.5% w.b.) by a solar bubble drier. The dried maize grains were kept in hermetic bags (Purdue Improved crop storage bag and GrainPro) and non-hermetic bags (ZeroFly, woven polypropylene bag with plastic liner, and woven polypropylene bag) at room temperature for 6-months. Maize grain moisture content was measured and occurrence of mold on the grain was investigated at 3-months interval during storage. Minitab software package (version 19.2) was used for data analysis. At the onset of the experiment, the moisture content of maize grain was 12.93% (w.b.), and it was increased to 14.31% (w.b.) in woven polyethylene bags but kept constant in hermetic bags at the end of the 6-month storage. Overall, maize grain that threshed mechanically and kept in non-hermetic bags had higher moisture content than hermetically stored ones. Consequently, the incidence and frequency of fungal growth was increased with storage duration in non-hermetic bags. After 6 months of storage, the greatest levels of Aspergillus, Penicillium, and Fusarium spp. were found in maize threshed mechanically at 23% moisture content and kept in woven polyethylene bags. Generally, hermetic bags are more suited for preserving stored maize grains from fungal invasion throughout storage periods weather it is threshed mechanically or on hand.