Transformation Of Deoxynivalenol And Its Acetylated Derivatives During Bread And Steamed Bread Making Process

Fusarium Head Blight(FHB), a major fungal disease in cereals, could seriously impact the quantity and quality of wheat. F. graminearum is one of the most prevalent species that causes FHB in China. Mycotoxins produced by F. graminearum could potentially threat the health of human and livestock. This work aimed to study the stability and transformation profile of deoxynivalenol(DON) and its acetyl-derivatives(3-ADON and 15-ADON) during wheat based products making process. The potential impacts of processing parameters on the transformation profile of ADONs were assessed. And the possible mechanism of deacetylation of ADONs were discussed. It is important for assessing the risk and setting maximum limits of mycotoxins in cereal-based products. The main results were as follows:1. Changes and transformation of DON and ADONs during bread making processThe stability and conversion profiles of spiked DON, as well as its conjugates 3-ADON and 15-ADON were evaluated in mycotoxin-free wheat flour during bread making process, including kneading, fermentation and proofing. The results indicated that there was no significant differences(P<0.05)during dough preparation process. While a reduction of DON level ranged from 4% to 14% was observed during baking process(220℃,20 min) depending on the spiking levels. Four degradants of DON, namely, nor DON A, nor DON B, nor DON C and nor DON F were detected by UPLC–MS/MS in bread crust, while no degradants of DON were found in bread crumb. We also found that 3-ADON and 15-ADON could partly deacetylate and transformed to DON. It suggested that more strictly control on maximum limit of DON should be setted, due to some derivatives of DON during bread making process.2. Changes of mycotoxins and effect of processing factors on deacetylation of 3-ADONThe levels of DON and NIV were stable and no substantial changes were found during Chinese steamed bread making process, including kneading, fermentation and steaming, which suggested that fusarium toxins were stable during food making process. 3-ADON and 15-ADON partly lost acetyl group and converted to DON during steamed bread making, with the conversation ratios of 47.2%-76.9% for 3-ADON and 52.4%-91.6% for 15-ADON based on the spiking levels. Moreover, the study demonstrated that alkaline condition and increase of steaming time are disadvantage of deacetylation of 3-ADON. It can be used to control the damage of mycotoxins by applying appropriate processing technology.3. Mechanism on deacetylation of 3-ADONIn order to reveal the possible mechanism on deacetylation reaction of 3-ADON, the matrixes of wheat water-soluble proteins(albumin), globulin, prolamin and glutenin were used to survey the effect on deacetylation of 3-ADON, respectively. The results showed that the water-soluble proteins played a vital role on deacetylation of 3-ADON. After separation, purification and structure elucidation of these water soluble proteins, we might suggest that the active ingredients, which possess the deacetylation of 3-ADON were water soluble enzymes with molecular weight of 45-72 k Da. It revealed the mechmism of deacetylation of 3-ADON and 15-ADON during wheat-based products making process.