Characterizing effects of fermentation and baking on the deoxynivalenol content of rolls

The effects of fermentation and baking on the deoxynivalenol (DON) contamination level of rolls prepared with contaminated wheat flour were studied. Contaminated wheat was obtained from a field experiment where wheat heads were inoculated at anthesis using a Fusarium graminearum macroconidial suspension. The DON contamination level of dough decreased linearly by 45 % within a fermentation (32°C, 75 % relative humidity) period of 90 min. The decrease of the DON content in the dough due to fermentation was not related to yeast, starch or gluten. The DON contents of flour/ water mixtures were decreased under fermentation conditions, whereas no effect was observed if fermentation was omitted. After the centrifugation of flour/water mixtures, the effect of fermentation was observed in the supernatant, but not in the sediment, suggesting that a yet unidentified water-soluble compound of the flour was responsible for the reduction during fermentation. The DON content of rolls decreased almost linearly with baking time (0 - 20 min) but it was not significantly affected by baking temperature (220 vs. 250 °C).The DON content of the rolls decreased during baking at an average rate of 0.35 ± 0.05 mg DON kg-1 dry mass min-1. Fermentation and baking decreased the DON content of the rolls to a similar extent, but a combination of both processes (fermentation with subsequent baking) did not result in a better reduction than one of the steps alone. The latter result suggests that the compound(s) responsible for the decrease of the DON content during fermentation is/are not heat stable. The DON contents of crust, dough and whole rolls did not differ significantly and the distribution of the DON within the rolls was not affected by yeast.