Study On Distribution Of Mycotoxins In Wet Processing Products Of Scabby Wheat

To study the distribution characteristics of mycotoxins of scabby wheat in the chain of wet processing, three kinds of scabby wheat were surveyed as the research object firstly in the work, and the basic pollution situation and transfer characteristics of mycotoxins in laboratory grinding products were studied; Later on, an infected deeply scabby wheat was selected and winnowing classified into four kinds of wheat, and quality characteristics of them were studied; Then the corresponding wheat flour were wet separated and the distribution characteristics of mycotoxins and the basic characteristics of processed products were studied; Finally, the crude starch obtained by wet separation was used in alcohol fermentation, and the distribution characteristics of mycotoxins in enzymolysis and fermentation products were analysised. The results show that:The contents of fusarium mycotoxins in scabby wheat, such as deoxynivalenol(DON) and Zearalenone(ZEN), as the representative of the mycotoxins, were far more higher than the national standard, while the pollution phenomenon of Aflatoxin B1(AFB1) and Ochratoxin A(OTA)was not obvious; There was significant difference for the mycotoxin contents in the systems after grinding and milling, and the contents of coarse bran, short bran and whole wheat flour were much higher than other flour flows. The highest reduction rates of DON, AFB1, ZEN contents in break and middle millings were separately 41.44%, 61.76% and 93.24% respectively when compared with the corresponding whole wheat flour, while the distribution of OTA was not obvious.The DON, ZEN contents of three kinds of scabby wheat I, II, III with different infection degrees, which were obtained by winnowing classification from a deeply infected sample, all displayed a rising trend, and had striking difference with unclassified wheat, so the classified treatment had a remarkable effect on the redistribution of scabby wheat. The wheat grain characteristics, quality properties, pasting properties and rheological properties of scabby wheat with different infection degrees all occurred deterioration, and were significantly different. And the higher the mycotoxin content, the deeper the deterioration degree.The wet separation had a significantly effect on the distribution and transfer of mycotoxins in wheat flour. In the wet separation products, most of the DON would transfer to the wash water, and the DON contents of crude starch and gluten were reducted separately to 14.97-29.59%, 19.22-38.07% of wheat flour while water soluble(dry basis) enriched 58.41-66.43 times of wheat flour; The ZEN contents decreased by 68.67% maximally in the crude starch, while wheat gluten enriched highestly 6.00 times of wheat flour and water soluble(dry basis) enriched 6.88 times on average; The study showed the bondage between DON, ZEN with protein in flour was more easily than with starch, especially ZEN. The quality characteristics results of the products showed that, the coarse starch which was extracted from the deeper infected flour showed smaller whiteness, worse pasting properties and pellucidity etc., but the characteristics of purity, yield, solubility, swelling power, aging rate of starch paste had small difference compared with the crude starch of lighter infection degree. While the whiteness, purity, water absorption rate, water holding, oil holding capacitythe of corresponding gluten were all getting worse and the quality were reduced.Enzyme and yeast treatment had striking effects on the change and transfer of mycotoxins in the wheat crude starch, the contents of mycotoxins in the whole fermentation process showed a firstly increased and then decreased trend. The mycotoxin contents elevated significantly after α-amylase and glucoamylase treatments, and the decrease rates of liquefaction stage were greater than the saccharification stage; After fermentation of yeast, the contents of DON, ZEN in fermentation broth decreased significantly, and fermentation supernatant after centrifugation had further decrease compared with fermentation broth, while the contents of DON, ZEN of dry distillers’ grains separately enriched highest 27.93, 56.82 times of fermentation broth and indicated that mycotoxins are mainly concentrated in the distiller’s grains; Wheat scab infection would cause partial loss of alcoholic fermentation stage, therefore the contents of residual reducing sugar were higher than the usual fermentation, and the ethanol contents of fermentation supernatant decreased with the developing of scab.