【作者】 朱玉昌；

【导师】 刘阳；

【作者基本信息】 中国农业科学院 ， 农产品质量与食物安全， 2014， 博士

【摘要】 脱氧雪腐镰刀菌烯醇（DON）毒素污染小麦的现象广泛存在于全球各国，其对小麦的污染率以及污染水平居于镰刀菌毒素的首位，在赤霉病大规模爆发时更严重。被DON毒素污染的小麦进入食物链，会对人畜产生急、慢性毒性，细胞毒性等，引起肾中毒、肝中毒、生殖异常以及抑制免疫反应，因此全球各国均建立了完善的限量标准，及时剔除毒素超标的籽粒进入食物链极为重要。被镰刀菌及DON毒素污染的小麦籽粒外观皱缩，比重较正常籽粒小，可借助此差异利用重力分选技术将其从正常小麦中分选出来。本论文利用LA-K实验室用重力分选机考察了不同机械因素对DON毒素污染水平不同的小麦的分选效果；基于重力分选机的基础原理，通过考察DON毒素污染籽粒在分选过程中的分布，对其核心部件振动筛进行了设计；试制了重力分选样机，分析了不同机械因素对分选效果的影响，并进行了分选性能评价；通过分析毒素污染籽粒在筛面上形成稳定的理想分布的过程，阐述了研制的重力分选机分选效果显著提升的原因。主要研究结论如下：（1）使用现有的重力分选机可将自然污染DON毒素的小麦中的高DON毒素含量小麦籽粒分选出来，对于不同污染程度的小麦，其分选效果与设备的机械参数密切相关。为了高效、经济地将污染小麦中的高DON毒素含量籽粒分选出来，可对不同批次的DON毒素污染小麦在一系列分选试验的基础上建立分选模型，再通过模型的推导得到理想分选效果的机械参数，使用于后续加工的小麦中的DON毒素含量低于我国限量标准；（2）设计了一种在出料边带出料装置的振动筛，上层毒素污染籽粒可高度聚集在筛面轻质端侧。该出料装置为一体式结构，紧密固定于筛面出料边，不易脱落，结构紧凑，拆装方便；（3）研制的重力分选机仅进料速率、筛面振动频率及风速对筛面毒素污染籽粒料层的形成和分布有不同程度的影响；筛面振幅、横向倾角和纵向倾角在一定范围内的变化对分选效果无显著的影响；（4）研制的重力分选机具有结构简单，实施方便，造价低廉，使用方便的优点，在DON毒素污染小麦分选效果方面，经与LA-K重力分选机对比，毒素污染籽粒被分选出的几率更高；（5）研制的重力分选机能实现高效分选DON毒素污染籽粒的原因在于其改变了被分选的DON毒素污染小麦在筛面的扩散运动，形成更有利于毒素污染籽粒高度集中分布的涡旋运动，并形成垂直于出料口的条带状料层，因此具有独特的优势。更多还原

【Abstract】 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.更多还原