Study On The Separation Technology And Equipment For DON-contaminated Wheat With Gravity Separator

Deoxynivalenol (DON), commonly referred to as vomitoxin, is one of the predominanttrichothecenes found as natural contaminants in wheat infected by Fusarium, like F. graminearum and F.culmorum. The worldwide occurrence of DON in wheat has been well documented over the last twodecades. The toxins of DON have been proved to be able to cause a variety of toxic effects in bothexperimental animals and livestock, and on some occasions, toxins produced by DON have also beensuspected to cause toxicity in humans. As a consequence, different maximum levels for DON in wheatand wheat-based food have been proposed in different countries, so it is essential to prevent it fromentering the food chain. Wheat with DON become shrivelled and lower in weight than healthy ones andcan be separated on the basis of specific gravity by the use of gravity separators.By applying LA-K gravity separator, the effects of machine parameters, including vibrationfrequency, airflow, lateral slope angle, longitudinal angle and amplitude of screen box on separationresult of DON-contaminated wheat were investigated. Basing on the basic principle of gravityseparation technology, a kind of deck, which was the critical component of machine, was designedaccording to the distribution of DON-contaminated wheat on the deck during processing, and animproved separator was designed with the deck, and the effects of six machine parameters ondistribution of DON-contaminated wheat over the deck in separation process were investigated, and theseparation efficiency was evaluated.Conclusions are as follows:(1) DON-contaminated wheat could be separated from healty ones by gravity separator. For wheatwith different DON content, the separation efficiency was closely related to machine parameters. Inorder to efficiently and economically select wheat with high content of DON, the optimal values of theparameters were deduced by establishing mathematical model for both the percentage of chosenDON-contaminated wheat and its mass fraction of DON and then by synthetic membership scoreconsidered analysis.(2) A deck with a kind of discharge device on the discharge edge was designed, the upperDON-contaminated wheat formed centralized distribution near the light side of the deck. The dischargedevice tightly fixed on the deck was characterized by its one-piece structure, unlikely to drop out,compact-sized and easy disassembly.(3) The separation efficiency for DON-contaminated wheat with improved gravity separator wasaffected by feeding rate, oscillation frequency and air velocity, while amplitude, lateral slope angle andlongitudinal angle had no impact on the separation result.(4) The designed separator was characterized by simple structure, easy implementation, low cost andeasy to use. Compared with LA-K gravity separator, the mass fraction for DON-contaminated fractionwas higher while the proportion was lower, indicating that the improved technology could highlysorting DON-contaminated part from the contaminated wheat.(5) With the improved gravity separator, the pathway for DON-contaminated wheat during the course of separation changed, rather than decentralized but gathered as banding near its discharge gate,efficiently and economically removed from healthy wheat.