Fate of deoxynivalenol and deoxynivalenol-3-glucoside during wheat milling and Chinese steamed bread processing

To investigate the fate of deoxynivalenol (DON) and deoxynivalenol-3-glucoside (D3G) during wheat milling and Chinese steamed bread (CSB) processing, Fusarium-contaminated wheat samples containing DON and D3G at five different levels were milled and processed to CSB. Mycotoxin levels in milling fractions, doughs and CSB were determined with UPLC-MS/MS. Concentrations of DON and D3G were 1.2–2.2 times and 2.9–4.4 times higher in bran than that in wheat grain and they were slightly lower in shorts compared to bran. Reductions of 79–90% for DON and 23–39% for D3G in flour were observed, respectively, compared to wheat grain. With respect to wheat grain, the distribution of DON was 35% in bran, 27% in shorts, and 9% in flour, and the distribution of D3G was 77% in bran, 58% in shorts, and 37% in flour. Milling decreased the total amount of DON but increased the amount of D3G, which may result from the binding of DON to starch during the milling process. DON levels approximately doubled when the mixed and fermented dough was processed into CSB. D3G concentrations in mixed and fermented doughs and in CSB did not differ significantly, but were almost 50% lower than in flour. Dough making decreased the amount of D3G and steaming increased the amount of DON. CSB processing may thus release bound DON in flour.