Natural occurrence of masked deoxynivalenol in Chinese wheat and wheat-based products during 2008-2011

Abstract

A total of 697 samples of wheat and wheat-based products collected from 24 provinces in China during 2008-2011 were analysed for deoxynivalenol (DON), deoxynivalenol-3-glucoside (DON-3G), 3-O-acetyldeoxynivalenol (3-ADON) and 15-O-acetyldeoxynivalenol (15-ADON) by ultra-performance liquid chromatography tandem mass spectrometry (LC-MS/MS). DON was the predominant toxin detected abundantly and frequently. Nine wheat flour samples were positive for DON at levels exceeding the Chinese regulatory limit of 1000 μg/kg for DON in wheat. Moderate concentrations of DON-3G and lower concentrations of both 3-ADON and 15-ADON were found in the presence of high DON levels. DON-3G was detected at concentrations of 4-238 μg/kg (mean 52 μg/kg) in wheat kernels and 3-39 μg/kg (mean 11 μg/kg) in wheat flour in 2008; and 3-235 μg/kg (mean 22 μg/kg), 3-53 μg/kg (mean 14 μg/kg) and 3-87 μg/kg (mean19 μg/kg) in wheat products in 2009, 2010 and 2011, respectively. The average relative ratio of DON-3G to DON was 33±3% in wheat kernels and 10±1% in wheat flour in 2008; and 22±7%, 9±4% and 14±7% in wheat products in 2009, 2010 and 2011, respectively. The natural occurrence of DON-3G is positively correlated with that of DON in all samples over the 4-year period. DON-3G was present at a level higher than 3-ADON and 15-ADON in all samples examined, possibly due to the fact that a higher level of DON, the precursor of DON-3G, was found compared to either 3-ADON or 15-ADON. As for the toxin proportion, DON-3G accounted for 30% (wheat kernel) and 13% (wheat flour), as well as 14%, 11% and 13% of the total 4 toxins tested in 2008, 2009, 2010 and 2011 samples, respectively. These results indicate the importance of considering DON-3G with regard to setting a regulatory limit for DON in Chinese wheat and wheat-based products.