Studies On Determination Of Bound Deoxynivalenol In Barley And Malt Samples Infected With Fusarium Head Blight

Fusarium Head Blight (FHB) is a fungal disease commonly occurred in barley, wheat and some other small grains. It prevelance results in not only the reduction of quality and quantity of crops, but the contamination of mycotoxins. Recently the bound mycotoxins, particlarly bound deoxynivalenol(DON) has raised more interest since it escapes the routine detection, but can be released after digestion in human and animals, which poses potential threat on the food safety.The impact of particle size and enzymatic treatments were investigated on the determination of deoxynivalenol (DON) in FHB-infected barley samples. The results showed that the fine-grind samples generally yielded higher reults than medium and coarse grinds. Three determination methods(GC-ECD, GC-MS, ELISA) were used to compare the accuracy to detect DON. This trend was most pronounced in samples with higher DON content. Enzyme treatments involved either amylolytic(alpha-amylase/AMG), proteolytic (papain) or cell wall degrading (cellulase/xylanase) enzymes. Papain treatment resulted in significant increases (16-28%) in the amount of DON detected in five of the seven samples tested when compared to the untreatment samples or enzyme controls. The results strongly suggested that FHB infected barley samples can contain bound DON.Doehlert matrix design was performed to determine the optimal conditions for the time, temperature of heat hydrolysis and the concentration of TFA to determine the total DON content in barley samples with TFA hydrolysis. The optimal conditions were 133℃for temperature,54 min for time and 1.25M for TFA concentration. Statistic analysis shows that variable the total DON had largest response on the optimal point in the model established. Verification of the method was also investigated on different barley samples. Recovery tests of DON,3-ADON and 15-ADON and additional verification tests proved that this procedure could be applied for analysis of other FHB infected barley samples with this matrix.With the optimal conditions of TFA hydrolysis, the occurrence of bound DONin FHB infected barley and malt samples on GC-ECD. The presence of bound DON was observed in almost 40% of barley samples. The results of bound DON in malting samples showed that after steeping the content of free DON decreased dramatically together with bound DON. The fact that so much bound DON was lost during steeping suggests that bound DON appears likely to be water soluble and DON-glucosides would be expected to be at least partially water soluble.