Influence of Water Activity and Time Duration on Fusarium Mycotoxins Production in Maize Grains During Post-Harvest Storage

This study investigated the influence of water activity (aw) and storage time on total fungal and Fusarium counts and mycotoxins zearalenone (ZON), trichothecenes type-A (i.e. T-2 and HT-2) and trichothecenes type-B (i.e. DON, 3-ac DON, 15-ac DON) production in maize grains. Water activity of the grains was adjusted to 0.85, 0.90 and 0.95 aw and the samples were stored at 25°C for 45 days. The control samples were kept without any aw modification. At 15 days interval, the samples were analyzed for the aforesaid parameters. The data showed that aw and storage time alone and interactively significantly (p 0.05) affected the analyzed parameters. The lowest total fungal counts (12.26×10³ CFUs/g) were recorded in 0.85 aw sample at the start of storage, whereas the highest total viable counts i.e. 18.01×10³ CFUs/g were documented at day 45 in the grain sample of 0.95 aw. The total Fusarium count varied from 0.42×103 CFUs/g in control sample at the start of storage time to 0.94×10³ CFUs/g at day 45 in the sample modified to 0.95 aw. The lowest ZON (855.50 μg/kg), DON (1246.45 μg/kg), 3-ac DON (234.41 μg/kg), 15-ac DON (90.58 μg/kg), T-2 (221.15 μg/kg) and HT-2 (221.24 μg/kg) were recorded at the onset of storage time in the sample of 0.85 aw, whereas these mycotoxins steadily increased and attained the highest values at the uppermost marginal values of aw and storage time.. It was concluded that fungal growth and mycotoxins production in maize grains were favored by elevated aw and increasing storage time. Therefore, it is recommended that cereals grains should be kept at reduced aw to prevent fungal growth and subsequent mycotoxins production in the grains during post-harvest storage.