Primary Study Of Fusarium Sp.and Deoxynivalenol Effect On Malt Quality

By taking infected malt with Fusarium sp. as the main research object, an analytical method of deoxynivalenol (DON) in barley, malt and beer using high performance liquid chromatography (HPLC) was established. It has successfully separated based on a reversed-phase Agilent Zorbax Eclipse XDB-C18 (250mmx4.6mm,5μm), and the mobile phase was a mixture of methanol and water with phosphoric acid (0.05%,v/v) at (20:80, v/v). In addition, column temperature was maintained at 30℃with flow rate of 1.0mL/min. The detecting wavelength was 210 nm. The linear relationship was good. The average rate of recoveries of barley, malt and beer were among 86.55%-90.58%,92.53%-101.22% and 82.95%-96.92%, while RSD<4%. It was proved to be a convenient and correct method for detecing deoxynivalenol content in barley, malt and beer.DON in malt was mainly come from two sides, one was malting barley with DON, the other was infected malt with Fusarium sp.. Four Fusarium sp. was used in the thesis, such as F.graminearum, F. nivale, F. moniliforme, F. avenaceum and so on, and DON content of each Fusarium sp. with different inoculation was detected during malting. DON content was significantly increased in green malt at the end of germinate. It was found that the beer non-biological stability would be seriously damaged because the wort turbidity was increased greatly with infected malt.It was researched that the spore and mycelium of Fusarium sp.& infected malt, including protein, poly phenolic,β-glucosan, xylan and a-amion nitrogen, because the wort turbidity was unnormal after inoculating Fusarium sp. spore in barley while malting. Then, a conciusion was reached that the increasing of wort turbidity was caused by the protein secreted by Fusarium sp., and a linear regression model between protein and turbidity was built by using SPSS 17.0, which was y=0.181x-18.877 (x is the content of protein,y is turbidity). With five day pure culture of Fusarium sp. on bran medium, after purified with Sephdex G-100, two obviously turbidity-induced protein was obtained, which displayed as a molecular weight 44&56KDa from the SDS-PAGE electrophoresis. Both DON and protein were producted by Fusarium sp., so the correlation between infected malt DON content and wort turbidity was researched in this paper. The turbidity of wort increased, moreover, the unnormal wort turbidity was caused by the high protein content, May be the barle infect with Fusarium sp., so the content of DON in malt should be detected.