Dynamics of Mycotoxins, Microbial Communities, and Quality of Corn When Stored at Various Temperatures

Corn is a major grain crop in China; however, mycotoxin contamination during storage threatens grain quality. In this study, naturally contaminated corn was stored at 15 °C or 35 °C under 65 ± 5% relative humidity for 8 months, with monthly sampling. Mycotoxin contents and fungal communities were analyzed, and the major quality indicators of corn were evaluated. Under both storage conditions, aflatoxins and ochratoxin A remained below detection limits. At 15 °C, fumonisins B1 and B2 decreased by 3.2% and 2.5%, respectively, after 8 months of storage. FB3 reached 41.51 ± 2.10 μg/kg at month 8, representing a 17.3% decrease. Deoxynivalenol and zearalenone remained relatively stable. At 35 °C, the concentrations of FB1, FB2, and FB3 reached 414.85 ± 3.27, 59.52 ± 1.53, and 91.76 ± 2.04 μg/kg, respectively. These five toxins increased by 13.8%, 40.0%, 82.8%, 10.4%, and 26.1%, respectively. Analysis of fungal communities indicated that dominant taxa differed between storage conditions, with higher relative abundance of Fusarium at 35 °C and higher Trichoderma at 15 °C. Storage at 35 °C resulted in a significant decrease in crude fat, starch content, germination rate, and antioxidant enzyme activity compared with conditions at 15 °C, while free fatty acid content increased. Storage at 15 °C limited toxin accumulation and quality deterioration compared with 35 °C. Temperature control can therefore improve corn preservation.