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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Different Post-Harvesting Drying Temperatures on Aspergillus Flavus Survival and Aflatoxin Content in Five Maize Hybrids

Authors
item Hawkins, Leigh
item Windham, Gary
item Williams, William

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 13, 2005
Publication Date: June 1, 2005
Citation: Hawkins, L.K., Windham, G.L., Williams, W.P. 2005. Effect of different post-harvesting drying temperatures on Aspergillus flavus survival and aflatoxin content in five maize hybrids. Journal of Food Protection. 68:1521-1524.

Interpretive Summary: After harvest corn is dried artificially to halt the growth of fungi and mycotoxin production while in postharvest storage. The process often limits harvest capacity and has been a frequent cause of seed injury. Higher drying temperatures could lead to shorter drying periods and faster turnover; however, there is often a deterioration of the physical quality of the grain, including increased breakage susceptibility and loss of viability. The goals of this study were to determine the effect of drying temperatures on fungal survival and aflatoxin content in corn and determine the viability of the seed subjected to different drying temperatures. Drying temperatures had no effects on aflatoxin concentration given the heat stability of the toxin. With increased temperatures from 40 to 70°C, there was a significant decrease in germination and a significant increase in stress cracks. At 60°C, F. verticillioides kernel infection is significantly reduced. Aspergillus flavus kernel infection was reduced from 11% to 8% as drying temperatures increased from 40 to 60°C. This information is useful in determining a safe range of temperatures that may be used for drying corn seed.

Technical Abstract: After harvest, maize is dried artificially to halt fungal grown and mycotoxin production while in post harvest storage. The process often limits harvest capacity and has been a frequent cause of seed injury. Higher drying temperatures could lead to shorter drying periods and faster turnover; however, there is often a deterioration of the physical grain quality, including increased breakage susceptibility and loss of viability. The goals of this study were to determine the effect of different post-harvest drying temperatures on Aspergillus flavus and Fusarium verticillioides survival and aflatoxin content in maize and to determine the viability of the seed. Five corn hybrids varying in resistance to Aspergillus flavus were side-needle inoculated with A. flavus, harvested at physiological maturity, and dried at temperatures ranging from 40-70oC. Kernels were evaluated for aflatoxin, stress cracks, germination, and kernel infection by A. flavus and a natural infestation of F. verticillioides. Drying temperature had no effects on aflatoxin concentration given the heat stability of the toxin. With increased temperatures from 40 to 70oC, there was a significant decrease in germination from 96% to 27%; and a significant increase in stress cracks (1.4 up to 18.7). At temperatures above 60oC, F. verticillioides kernel infection was significantly reduced to less than 18%. At 70oC, there was a significant reduction in Aspergillus flavus kernel infection from 11% to 3%. This information is useful in determining a range of temperatures that may be used for drying seed when fungal infection, stress cracks, and seed viability are of interest.

Last Modified: 4/23/2014
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