Research Of Semolina Flour Characteristics And The Noodle Quality

Semolina flour,commonly known as granulated wheat flour,is produced with lower grinding strength and larger particle size.These days,the concept of"moderate processing"of wheat flour is gradually adopted by more and more wheat milling enterprises,and the production of semolina flour can help to save energy and reduce consumption.In this study,the characteristics of semolina flour were systematically evaluated,the influence of particle size variation of semolina flour on the production process of dried noodle and fresh noodle was analyzed in order to investigate the mechanisms affecting the quality of semolina flour.Firstly,the differences of characteristics between 8 types of semolina flour and 1 type of common wheat flour were investigated.The maximum particle size of semolina flour in the range of 130.03-153.17μm（P<0.05）was significantly higher than that of common wheat flour（103.83μm,P<0.05）.The larger particle size gives the semolina flour a yellowish and gloomy color,but its endosperm granules have less brokenness,lower damaged starch content（<15.65%）,higher gluten index（>88.10%）and better gluten quality.The semolina flour showed lower water solubility and less starch swelling ability.Water solvent retention capacity,sucrose solvent retention capacity and sodium carbonate solvent retention capacity were significantly lower than that of common wheat flour（P<0.05）.In pasting characteristics,semolina flour possessed higher peak viscosity,final viscosity and regrowth values and lower breakdown values.The rheological tests showed that the semolina flour dough exhibited higher mixing resistance and better extensibility.Secondly,the effect of particle size variation on the properties of semolina flour was discussed.By grinding the semolina flour with a ball mill,the particle size was decreased to the level of common wheat flour,the"sand-like"texture of the semolina flour disappeared to become slightly denser.Moisture content decreased,damaged starch content increased,and the wet gluten content and gluten index decreased.The four solvent retention capacity of the semolina flour is increased.The drop in particle size resulted in decreased total pentosan content and increased soluble pentosan content.Damage of starch caused a drop in the falling values of,with a decrease in the peak pasting viscosity and final viscosity as well as an increase in the breakdown.In rheological tests,crushed semolina flour showed an increase in water absorption,higher dough weakness,lower dough quality index,and a decrease in extension energy and extensibility suggesting that crushing caused a loss of viscoelasticity of dough.Thirdly,the production quality and cooking quality of low-moisture noodles from semolina flour were investigated.During the noodle making process,semolina flour easily developed large size dough crumbs（>4.5 mm）,which accounted for more than 10%of the total dough crumbs mass,while the large size part of the dough crumbs of common wheat flour accounted for no more than 7%.The combined water in the crumbs of semolina flour is lower and the water distribution is less equal.The color of semolina flour dough sheet was darker and yellowness value was higher,but the shear resistance of the dough sheet was smaller and the percentage of recoverable deformation was larger.The flexibilities of dried noodles of semolina flour were significantly higher than those of crushed semolina flour and common wheat flour noodles（P<0.05）,with longer cooking time and higher water absorption,but their cooking losses were higher.The hardness and adhesiveness of the cooked noodles were lower,and the extension distance was longer（>31.06 mm）.FTIR showed that semolina flour starch had a better short-range order and a more homogeneous crystal structure.SE-HPLC showed that semolina flour dried noodles possessed a higher extractable rate of singlet protein.Fourth,research was conducted to determine the effect of particle size variation of semolina flour on the quality of high-moisture dough and its storage process,evaluating the cooking quality of fresh noodles with semolina flour.After 12 h storage at ambient temperature,the quality of high-moisture dough began to deteriorate significantly,with a decrease in extension energy and extension resistance,decrease in G’and G",increase in tanδand maximum J_-Max,dough thinning and mobility increase.The semolina flour dough had higher extensional energy and higher J_-r/J_-Max.G’and G"of the crushed semolina flour dough were higher with higher deformation resistance.During storage,the water activity of semolina dough was lower and the free sulfhydryl groups increased more slowly.SE-HPLC showed that the extraction rate of the SDS-extractable protein was higher in the crushed semolina flour dough after storage.SEM showed that the internal structure of the semolina flour dough was more porous and a greater number of starch particles were embedded in the gluten network,forming a gluten-starch complex.The agglomeration of starch in the crushed semolina flour dough was significant.The water absorption rate of fresh noodles made from semolina flour was significantly higher than that of crushed wheat flour（P<0.05）,with lower cooking loss rate and better elasticity and chewiness.Finally,the effects of different storage temperatures on the quality of semolina flour dough and fresh noodles were investigated.The results showed that:elongation and tensile resistance of the dough were significantly higher（P<0.05）under refrigerated（4℃）than room temperature（25℃）storage conditions,refrigeration could effectively improve the deterioration of the quality of the dough during storage,and the cooking loss rate of fresh noodles was lower than that of room temperature storage conditions.Storage at room temperature accelerated the weakening of gluten quality,the gluten index decreased considerably（P<0.05）.The relative crystallinity of starch increased during dough storage,and the proportion of increased crystallinity was greater under room temperature storage conditions;the particle size and molecular weight of starch decreased,which was more pronounced in wheat flour dough with larger particle size.