| Pre-harvest sprouting is very common in the world wheat production, and has become one of the major natural adversities affecting wheat yield, quality and profit. Pre-harvest sprouting not only causes grain yield loss, but also influences contents of protein, starch, wet gluten. In extreme conditions, severely sprouted wheat grain is not edible, and Consequently causes severe profit loss to wheat producers and enterprises.Based on previous researches, grains of red wheat cultivar Ningmain14(NM14) and white wheat cultivar Yannong19(YN19) were germinated under artificially high temperature-and high humidity-controlled chambers for different duration. The changes in contents of the dominating biochemical components and the flour quality traits were then logged. The potential utilization approaches of the sprouting grains were also explored to reduce the economic losses in wheat due to pre-harvest sprouting.1.Effect of the sprouting on the protein content and dough rheological propertiesWith the increasing of the duration of sprouting, the content of total protein, gliadin, gluten and HMW-GS were decreased, while albumin and globin were increased. SDS-sedimentation value, dry-gluten and wet-gluten showed increased first and then decreased. Wet gluten was significantly reduced after64h and72h, which was had to collect to do the analysis. The water absorption rate, dough development time, stability time and broken time, were decreased with the increasing of the time germination duration, all the indexes were significantly reduced, except water absorption rate, compared with the control. All the results indicated that sprouting significantly affect the protein quality.2.Effect of the sprouting on the starch physiochemical property in wheat grainWith the increasing of the sprouting time, the amylase content was increased, while the total starch content was significantly reduced. The sedimentation value, swelling potential and the peak viscosity were decreased in the treated flour with the timing pass by, furthmore, reached to the lowest during16-24h, compared with the control.We also do the amalysis on the stach, the results showed the pasting parameters were also slightly decreased, only after72h treatment, the peak viscosity was decreased below 2000cp, there was no difference in swelling potential, compared with control. However, the starch content and average diameter of the A and B type granules were decreased with the duriation of sprouting. The Yannongl9and Ningmai14showed the similar tendency.The results showed that the sprouting lead to much serious effect on the wheat flour quality than the starch quality, seeds which measured after24h showed no significantly difference in the flour quality indexes compared with the control, which indicated the quality was not significantly affected in this treatment. The content of the A and B type starch granule were influenced by the duration of the sprouting time, while there was no significantly difference was found in the swelling potential and the peak viscosity, compared with control. The results indicated that the seeds after this treatment still can be used for processing, to improve the use efficiency of the sprouting wheat.3. The optimize of the starch extraction procedureThe results above showed that, the starch quality was slightly effected by the sprouting, which indicated can be used for further processing. In this study, according to the physicochemical properties of the seed quality formation, we use the process as, firstly, separate the protein gluten use washing, then get the starch supernant, then flow by purification with centrifuaging, at the end using the ethanol to extract the gliadin. Considering the effect of the concentration of NaOH, reaction time and temperature, and also the statistic analysis, we got the optimal processing paremeters:NaOH0.2%, Time50min, Temperature40℃, which we can get the yield of72.66%.This procure provide the processing guidance and improve the use efficiency of the sprouted seed. |
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