Study On Separating Effect For Protruded Wheat With Gravity Separator

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...