【作者】 李毅念；

【导师】 丁为民； 卢大新；

【作者基本信息】 南京农业大学 ， 农业机械化工程， 2005， 博士

【摘要】 小麦是我国的乃至全世界的主要粮食作物之一。在小麦收获季节,遇到连绵阴雨天,便会出现大面积的穗上发芽现象,使小麦的质量严重下降,明显降低小麦粉的食用品质和工艺品质,这种情况在世界范围内时常发生;另外在小麦的贮藏过程中,亦容易造成小麦的萌动或发芽;由于水解酶的水解作用,淀粉、蛋白质和脂肪等物质相应地被水解,水解产物供胚萌动和发芽所需要的能量和合成物质原料,这些能量物质的水解必然改变其原有的品质。如何有效地利用此类小麦成为一个重要的问题。在芽麦品质改良中改善发芽小麦品质的方法很多,国内外学者对此进行了很多研究。主要从物理和化学两个方面进行处理,物理处理方法包括重力分选法,加热处理法,剥皮制粉技术和搭配加工改善品质;化学处理方法主要为添加酶抑制剂——植酸或植酸钠。使用植酸或植酸钠作为酶抑制剂存在一定的毒性。在物理处理方法中,加热处理和剥皮制粉技术是对整批小麦进行处理,小麦籽粒受雨害或受潮而造成的萌动或发芽只是一部分,因此会产生不必要的损失。搭配加工改善品质的方法是以牺牲品质较好的小麦籽粒为代价。因此如何利用萌动籽粒或发芽籽粒与正常小麦籽粒间的物理性质的差异,采用一种有效的手段把萌动籽粒或发芽籽粒与正常小麦籽粒分离开,从而达到分选出已萌动籽粒或发芽籽粒,使整批小麦籽粒按小麦内部品质进行分级,对萌动籽粒或发芽籽粒再进行其它后处理,而重力分选法就是利用已萌动籽粒或发芽籽粒与正常小麦籽粒间的比重差异分选小麦的,这就为运用物理方法分离品质较低的萌动或发芽小麦籽粒提供了一个全新的思路。以此为主线本研究主要做了以下几项工作,并且得到了相应的结论: 1 为了避免小麦籽粒因个体间尺寸和比重的差异造成个体间发芽活力以及萌动干物质损耗的差异和应用精选加工控制小麦籽粒品质的思路,对一种小麦原样经粒径分级和重力分选两级精选加工后相关指标进行测试,测试结果表明,发芽率(发芽势)、容重值变化较大,通常是粒径越大,籽粒容重和发芽率越大;各粒径段再经重力分选后,容重值越大,发芽率(发芽势)亦越大;而食用品质指标,脂肪酸值,粗蛋白质含量和降落数值变化不大;通过精选加工获得了标准小麦籽粒样; 2 为了建立重力分选的理论基础和必要的理论依据,必须对经粒径分级和重力分选两级精选加工后的标准样进行萌动小麦籽粒干物质损耗的测试和品质分析,测试结果表明,随着萌动时间的增加,干物质的损耗亦增加,食用品质测试指标,脂肪酸值逐渐增加,粗蛋白质含量和降落数值相应地降低;对处于萌动阶段小麦籽粒的干物更多还原

【Abstract】 Wheat is one of the worldwide major crops. When raining occurs while wheat matures, grains will most possibly protrude or germinate on wheat spike in field, and this generally degrades wheat quality in a large extent and thus the edible and processing quality of wheat flour is reduced. This problem is common in the world. In addition to this, grains also protrude or germinate easily during storing period. Enzyme hydrolyzation decomposes starch, protein and fat, to supply energy and synthesize matter for embryo protruding and germinating. The hydrolyzating process consequently degrades starch, protein and fat quality. Therefore, searching an effective use of protruded and germinated wheat is an important issue. There are several methods for improving germinated wheat quality, on which many scholars in home and abroad have done a lot of studies. Those methods include both physical and chemical means. The physical methods include gravity separating, heating processing, peeling and accessorizing good wheat. The chemical process need to replenish enzyme inhibitor, phytic acid or sodium phytate, and the use of enzyme inhibitor has a certain degree of toxicity. Compared with this, if only part of the wheat is rain-damaged or damped, heating and peeling process will cause unnecessary loss, as it processes all wheat grains indiscriminatingly. Accessorizing good wheat is at the cost of high quality wheat. Therefore, it is promising to study the physical difference between the protruded or germinated and the normal wheat grains and to investigate the possibility of separating the mixture of two. The new idea is to grade wheat grains according to it’s internal quality, so that protruded or germinated wheat is separated and processed discriminatingly. This research concentrates on the specific gravity difference between the protruded or germinated and the normal wheat which is used for gravity separating. Based on the proposed idea, the following works have been done and some important results have been reached.1 To avoid the difference of germinating energy and dry matter loss resulting from variations of grains thickness and specific gravity, and apply a new idea of controllinguniform wheat quality, a cleaning and separating process was conducted. A breed of wheat was graded according to grain thickness and then separated according to it’s specific gravity, and several relative indexes were tested. Results show that variation of germinating rate (potential) and bulk density is larger than that of non-processed. In general, the larger the grain thickness, the higher the germinating rate and bulk density. Further gravity separating on several grain thickness sections wheat also shows that the larger the bulk density, the higher the germinating rate (potential). But the change of edible quality indexes is less than before grading and separating, such as fatty acid value, crude protein content and falling number. The standard grain is attained from this process.2 To establish a theoretical basis for gravity separating, testing on dry matter loss and quality of protruded standard wheat was necessary. The standard wheat was obtained through grading and separating original wheat grains in sequence. Results show that the longer the protruding time, the higher the dry matter loss. The edible quality indexes, fatty acid value increases gradually, but crude protein content and falling number decrease oppositely as protruding time increases.3 Based on the theory of gravity separation, standard wheat was cultivated at three different time stages, 8h, 16h and 24h, simulating raining effect on wheat in field. Then it was post-processed with enough time, two kinds of mixture cases for protruded and non-protruded wheat mixing were used. Firstly, while protruded wheat grains were mixed at 5%, 25% and 45% scales respectively with non-protruded grains for gravity separating, the results showed that gravity separating had a concrete effect on protruded grains, and the weight percentages for protruded grains were different in each discharge ho更多还原