Contamination Surveys Of The Deoxynivalenol In Wheat From Four Provinces In China In 2005

Deoxynivalenol (DON) is a mycotoxin produced by the Fusarium spp.and is present in the cereals everywhere in the world. DON has been proved tobe one of the most important toxins in head scab wheat. And China is acountry with a high incidence of wheat head scab, especially in southern areaof Huaihe River and the middle and lower reaches of Changjiang River. Thescab wheat can not only cause production losses of foodstuffs but also a fall inthe quality. More severely, it can lead to human and animal poisoning. It isnecessary to study the influence of various links on wheat head scab in wheatproduction practices so as to effectively reduce the incidence rate of wheathead scab and to instruct agricultural production activities.The present study selected wheat samples as objectives from 4 provincesin China and the established gas chromatogram (GC) method was used todetect the content of DON in wheat. Softwares such as SPSS and Excel wereadopted to process the data and analysis the DON contamination status ofwheat from different provinces as well as the association between variousfactors and DON contamination in wheat production practices.In this study 190 wheat samples(48 from Henan Province, 47 from Hubei,48 from Jilin and 47 from Sichuan Province)were tested with a contaminationrate of 66.32% and an average DON content of 19.28μg/kg. 162 samples weretested positive with an average DON content of 75.84μg/kg, which was lowerthan the result tested before in six provinces and one city including Henan etc.This may be attributed to the fact that the former test of DON only focused onthe wheat head scab epidemic regions, which results were usually higher andcould not represent the whole status of DON contamination in our country.Our results in this study suggested that the wheat from Henan had the highestDON content , It is middle in hubei and lowest in Sichuan and jilin 。Having compared the various links of wheat production practices, wediscovered that much rainfall in wheat growth period would aggravate thecontamination of the Fusarium spp.;while much rainfall in harvest time wouldprovide more opportunities for the wheat to contact the mycetes on the groundand to be recontaminated by molds after warehoused;the results of preventingmildew would be different if the weed killers were used at different time, theweed killed used before heading would have a better result than that of usedafter heading. DON content in wheat threshed by machine was lower than thatof threshed artificially. This maybe because the scab wheat is lighter with lowspecific gravity and can be easily isolated from the healthy one which reducesthe content of scab wheat. The wheat stored in warehouses and jars was foundto have a lower DON content than that of sacks. This could be attributed to thefact that warehouse-stored wheat lied in a ventilated low temperatureenvironment which effectively inhibited the fungal propagation. And thejar-stored wheat had a sealed and moisture proof environment that interruptedthe contamination of molds.The current study further improved the GC which has been acceptedinternationally. The improved GC had the lowest detection limit of 10ng/g, arecovery of 80.83%～90.65% and coefficient of variance less than 10%,whose sensitivity, specificity as well as repetitiveness well satisfied the presentinvestigation. Nitrogen gas was used as a substitution for argon-methanemixture to reduce the costs and its use should be extended. The flow rate of80ml/min was found to have the highest column efficiency. Packed columnwas substituted by capillary column for its nice isolation property. Thecapillary column of HP-5 (30m×0.52mm×0.25μm) is commonly used andsuitable for the detection of natural DON contamination with related chemicalcompound in cereals.The above results suggested that various links in wheat productionpractices correlated with the DON contamination extent of wheat, but theextent of association needed to be confirmed. further The current studyperfected formerly detection approaches and the accuracy, sensitivity andrepetitiveness of the newly established one well met the requirement of thisinvestigation.