Investigations on the kinetics of the concentration of deoxynivalenol (DON) and on spoilage by moulds and yeasts of wheat grain preserved with sodium metabisulfite (Na2S2O5, SBS) and propionic acid at various moisture contents

Unground wheat kernels contaminated with 2.09mg deoxynivalenol (DON) per kg dry matter were stored for up to 56 days at moisture contents of 15, 17.5 and 20% to study the alterations of DON concentration when the wheat was stored either unsupplemented or supplemented with 5g sodium metabisulfite (Na2S2O5, SBS), 10g propionic acid (PA) or 5g SBS plus 10g PA per kg. SBS addition alone or in combination with PA reduced the DON contamination to 1.2-4.3% of the initial DON concentration while DON concentration of unsupplemented and wheat batches supplemented only with PA varied inconsistently or remained unchanged. The SBS-related DON reduction was paralleled by a concomitant increase in the concentration of the non-toxic reaction product DON sulfonate. In contrast to the unsupplemented wet-stored controls, SBS addition prevented the growth of moulds and yeasts when added alone or in combination with PA. In conclusion, for the conditions examined, the wet preservation of DON-contaminated wheat with SBS seems to be promising as an on-farm detoxification measure.