Effect On The Screening Efficiency And Quality Of Wheat Flour

In this paper, the change of the screening conditions were studies on their relationships tothe wheat flour screening results firstly. And then through compare laser particle size analyserand screening test to obtain the discipline of screening ability. And the representative systemfour materials (2B,3B,1Mc,1M) on line are selection to screening and classification. Thendifferent types of physical and chemical properties of the sieving flour, rheological propertiesand quality characteristics of steamed bread were measured and analyzed, respectively. Themain results were shown as follows.In the grading screening progress of wheat flour, the cleaning effection of the bruse isbest. Sieve efficiency increased with the extension of screening time and sample weight,butreduced by water content and screening rate increasing in the same screening time. Thesieving way with mesh grading crowded is better.With the sieving time increase, the peak value deceased between10～50size interval,and increased between51～300size interval.The peak value of particle size distribute is stepright with the particle size largen. In sieving test, the screen-throughs change when particlesize is less than screen mesh, and bigger size particle is increase with sieving time extend.With particle size diminution, wheat flour ash content, chromaticity a and b valuegradually reduced, but chromaticity L value, gluten content, damaged starch, protein contentand subsiding value increased. The reducing sugar content increase in initial period, and thendecreased, but the falling number has the contrast trend. The gluten index and coarse starchcontent are increase by grading with particle size decrease.With the decrease of the particle size, the trend of wheat flour farinograph curveparameters increases firstly, and then reduce. Weakening degree had contrary trend. Ingeneral, extensorgraph parameters increased with the reduction of particle size, and thevariation trend of extension gradually reduced. Wheat flour particle size reduced, the doughresistance increased and the dough extensibility decrease. Wheat flour gelatinizationtemperature lessen with particle size reduced basically, and for different system flour has nodifference. In general, the viscosity decreased with particle lessen. The finally viscosityincreased with the reduction of particle size. Also, for difference system flour, the RVAindexs had diversity change. The specific volume, elasticity of the steamed bread got enlarged with the particle sizedecrease. When particle size largen, the steamed bread elasticity got better, and the hardnessgot better when particle lessen. Tincture of the steamed bread gradually got better with theparticle decrease. So, when we choose the flour to make steamed bread, the flour particle sizeis not too big or small, have to deal with in an integrated manner.