Influence of water activity and temperature on the accumulation of zearalenone in corn.

The influence of water activity (aw) and temperature on the zearalenone biosynthesis in corn has been examined. Viable corn kernels were conditioned at different values of water activity (0.90, 0.95 and 0.97), inoculated with Fusarium graminearum and incubated at different temperatures. Zearalenone was determined at selected times. For the strain used, a constant temperature of 25 degrees C resulted more favorable than 15 degrees C, 20 degrees C and the combination of two weeks at 25 degrees C followed by incubation at 15 degrees C shown by other authors to increase the zearalenone accumulation. Both F. graminearum growth and zearalenone production at 25 degrees C were inhibited at water activity 0.90. At short incubation times, toxin accumulation was greater at water activity 0.97 than at water activity 0.95 (25 degrees C). This relation was inverted at longer periods of incubation. A combined effect of water activity and temperature on the zearalenone accumulation was observed.