【作者】 黄曼；

【导师】 温其标；

【作者基本信息】 华南理工大学 ， 粮食、油脂及植物蛋白工程， 2010， 博士

【摘要】 TCK是我国进口粮食重要的A类检疫对象,开展绿色储粮技术研究,保护环境并确保我国粮食安全具有重要的战略意义。采用电子束辐照杀虫/菌技术,不仅对我国进口粮食中小麦矮腥黑穗病菌(TCK)的检疫,而且对于储粮害虫非化学防治研究,特别对华南高温高湿地区的粮食储藏工作具有重大意义。本论文研究了电子束辐照在线动态杀虫/菌的效果并深入研究了对小麦品质的影响,主要研究结果如下:在线动态辐照杀虫效果研究中,系统在试验设计的两种剂量(0.3kGy、0.6kGy)下,电子束能有效的杀灭储粮害虫,鉴于辐照的生物化学效应,害虫不会当场全部致死而是在7d内逐步死去。谷蠹对辐照剂量的抵抗力最强,其次是米象和赤拟谷盗。0.3~0.6kGy剂量范围作为电子束动态辐照杀虫的参考剂量是实际可行的。0.6kGy辐照剂量对该试验所有虫种和虫卵均有致死能力。.在动态辐照杀菌的实验研究中,电子束辐照对储藏小麦的菌落总数有极显著的抑制作用(P<0.01),菌落总数随辐照剂量的增加而降低;不同剂量辐照,对交、曲、镰、青、根霉菌属的抑制效果均达极显著水平(P<0.01)。不同的霉菌对电子束辐照的敏感性不同,依次为:交链霉属>曲霉属>镰刀菌属>青霉属>根霉属。本实验中,采用人工接种和模拟田间感染小麦试验的方法,研究了电子束辐照在线动态杀灭A类检疫病菌TCK的效果,发现电子束辐照对TCK冬孢子萌发有抑制和灭活效应,随着剂量的增加,TCK孢子的萌发率有规律地下降,TCK孢子萌发数量减少、萌发不正常、中止生长直至完全中止萌发,反映出TCK对射线的敏感性。3.6kGy电子束辐照剂量可以有效抑制和灭活TCK冬孢子,4.0kGy动态辐照TCK致死率达到90%或以上,而4.4kGy已经无法浸染小麦。EB辐照小麦种子的发芽试验结果表明,经过0.5~5.1 kGy EB辐照抑制了小麦种子的萌发,辐照剂量越高,种子萌发抑制越严重,辐照剂量对活力指数的影响最为显著。种子水分基本不变、色泽、气味检测均正常。种子膜透性测定结果显示,电子束辐照能够导致种子损伤,增加膜透性。EB辐照剂量与降落数值呈负相关,尤其是辐照剂量高于4kGy后,样品面筋指数和降落数值发生明显变化。从粉质仪曲线图测定的面团流变学特性表明,与对照相比,各剂量辐照水平样品的稳定时间和断裂时间等指标总体随着剂量的均有不同程度的增长;弱化度随着EB剂量变化也有所增加;吸水率和形成时间的变化并不十分明显,综合评价值略有减小。说明辐照剂量增加对面粉总体的品质是有一定负面影响的,剂量越高影响越大。小麦经1.0kGy辐照后制得面包、馒头品质仍然正常,3.5 kGy以下辐照后品质发生轻微变化,但仍属于正常食用范围;剂量高于3.8 kGy后,食用品质加速变差。TPA图谱分析表明,馒头的硬度、粘附性、弹性、粘聚性、咀嚼度、回复性这些品质指标之间显著相关(P<0.01),而EB辐照剂量与馒头的硬度、粘附性、弹性、粘聚性、咀嚼度、回复性品质指标显著相关(P<0.05)。EB辐照能部分破损小麦面粉中的淀粉颗粒,破损淀粉含量随着辐照剂量增大而增加,DSC研究结果表明,辐照剂量使小麦淀粉的热性质受到较大影响;小麦淀粉分子量研究结果表明,辐照后小麦淀粉分子量降低,且当辐照剂量达到4.4 kGy时,分子量降低了一个数量级,从而进一步阐释了经电子束辐照的小麦淀粉流变学特性的变化进而影响加工制品变化的实质是,EB辐照引起了淀粉分子结构的改变的结果。通过SDS-PAGE电泳和RP-HPLC研究发现,电子束辐照对麦醇溶蛋白的分子量、各组份蛋白的比例等没有特别明显的变化;但α/β醇溶蛋白亚基比例略微增大;辐照过的麦醇溶蛋白的园二色谱(CD)图谱峰发生了红移,吸收光值随着剂量的增大而增大,这说明在本实验剂量条件下,醇溶蛋白大分子发生了部分降解,但影响不是很大。而对麦谷蛋白低分子量亚基含量下降有较大的影响,剂量越高影响越大。这可能是EB辐照导致麦谷蛋白LMW-GS亚基大量分解和聚合反应,生成了不溶性大分子以至电泳谱带上和RP-HPLC峰值中LMW-GS亚基含量降低。更多还原

【Abstract】 Tilletia Cntroversa Kuhn (TCK) is the most important quarantine bacteria in imported grain of our country. To carry out green grain storage technology, protect environment and to ensure food safety in China has become an important strategic significance. Pesticides /bactericidal by electron beam irradiation technology is promised to play an important role not only in quarantine TCK bacteria in imported wheat but also for non-chemical control of pests in stored grain, especially for the grain storage in South China region with high temperature and humidity. The effectiveness of EB irradiation on-line to kill insects and bacteria dynamically were studied, effects on wheat quality were also included in this study. The main results are as follows:In the experimental design of two doses (0.3kGy, 0.6kGy), the electron beam on line can effectively kill pests in stored grain. In view of the biochemical effects of radiation, the insects died gradually in 7 days instead of immediately on the spot. Sitophilas Oryzae (L.) adults are more sensitive to the electron beam irradiation than that of Rhizopertha Dominica (F.). The range of 0.3~0.6kGy dynamic EB irradiation as a reference dose for insecticide is realistic. 0.6kGy dose of radiation are all death capacity to the test insect species and eggs. In the study of on-line irradiating sterilization experiments, EB irradiation can effectively inhibit the total number of stored wheat colony(P<0.01), the higher the radiation dose, the lower the total number of colonies. Different doses of irradiation were all highly significant inhibited to all species of fungus in this study. The sensitivity order to EB irradiation of fungus is Alternaria sp>Aspergillus> Fusarium> Penicillium> Rhizopus.In the study, the method of artificial inoculation TCK spores to affect wheat was used to study the effectiveness of online EB irradiation to kill TCK. It was found that EB irradiation can inhibit the germination of TCK spores and made them inactivation, the higher dose, the lower germination. The number of TCK spores germination was reduced with abnormal germinating or growing-stopped until the full suspension of germination, which reflected the radiation sensitivity of TCK. 3.6kGy dose of EB irradiation could inhibit and inactivate the winter TCK spores; the death rate of TCK was reduced by 90% or more with 4.0kGy on-line irradiation; wheat can not be disseminated in the dose of 4.4kGy.EB irradiation of wheat seed germination test results showed that, 0.5 ~ 5.1kGy EB irradiation inhibited the germination of wheat seeds, the higher the radiation dose, the more severe inhibition of seed germination.Radiation dose is the most significant to the vitality index. Water is essentially the same, color, odor testing were normal. Determination of membrane permeability of the seed showed that electron beam irradiation can lead to seed damage, increased membrane permeability.EB irradiation dose was negatively correlated with falling number, gluten index and falling number of sample changed significantly especially after radiation doses above 4kGy.Dough rheological properties from the Farinograph curve showed that, comparing with the control, absorption, stability, break time and other indicators of samples in each dose level of EB radiation were increased in varying degrees with doses. Evaluation value is negatively correlated with the degree of softening, and other water absorption, development time did not change very obviously.The quality of steamed bread made from 1.0kGy irradiated wheat is still normal while minor changes happened in the dose of 3.5 kGy, but it is still in the part of the normal range of consumption. When dose is higher than 3.8 kGy, the eating quality of steam bread became accelerated deterioration. TPA spectrum analysis showed that the quality indicators of bread as hardness, adhesion, elasticity, cohesiveness, chewiness, resilience were significantly correlated (P<0.01), while the EB irradiation doses were also significantly associated with all above bread quality indicators (P<0.05).EB irradiation can partially damaged starch granules in wheat flour and the damaged starch content increased with the increase of irradiation dose. DSC research results showed that the radiation dose affected the thermal properties of wheat starch significantly. Molecular weight study of wheat starch showed that wheat starch molecular weight were reduced after irradiation, and when the radiation dose is about to 4.4 kGy, the molecular weight reduced nearly an order of magnitude lower. Thus further explained that, the essence of rheological properties changes in wheat starch which also affected changes in processing products are the results of starch molecular structure changes because of EB irradiation.SDS-PAGE electrophoresis and RP-HPLC studies found that the molecular weight and proportion of protein units in gliadin were not particularly significant changed by EB irradiation, only ratio ofα/βsubunit slightly increased. The peak of the CD spectrum for EB irradiated-gliadin is in red shift and the absorption of light values increased with EB irradiation doses. It shows that under the conditions of the experimental doses, macromolecules in gliadin had been partially degraded while Low molecular weight glutenin subunits(LMW-GS)were decreased greatly, the higher doses, the more influence.更多还原