Study On The Effect Of Mixing Dough's Process To Steamed Bread Quality And Dough

In the production of steamed bread,mixing dough's process is the key processes.In the course of the process,a series of complex cross-linking polymerization of water,protein and starch in the dough will cause the dough to form specified characteristics and affect the quality of the bread.The characteristics of dough and the quality of steamed bread are affected by different mixing process and mixing modes.In this paper,I studied the dough forming mechanism and the variation of steamed bread quality in the dough mixing process.I studied the effect of dough mixing on the dough properties and steamed bread quality through the response surface experiment.I also compared different dough mixers and different mixing modes to study the variation of the dough and steamed bread.The main findings are as follows.Dough mixing changes the water status,so that water and starch,protein molecules through the intermolecular forces,disulfide bonds gluten molecules to form a certain secondary structure of gluten protein network,coupled with the filling starch granules,form a certain viscoelastic and gas-filled dough.And the change of moisture in the dough causes a series of other changes.When the dough is not fully absorbed,the deep bound water is less(9%)and the weak bound water is more(90%),which hinders the formation of disulfide bonds and hydrogen bonds,resulting in a large proportion of ?-sheet(40%~50%),resulting in less gluten content(21%).With the increase of the absorption of water,the transformation of weakly bound water(82%)to deep bound water(17%)promotes the formation of disulfide bonds and hydrogen bonds,and transforms ?-turn(35%)to ?-helix(28%)and ?-sheet(35%)destroys the hydrophobic interaction environment.The low molecular weight gluten and gliadin polymerization occurs to form a lot of gluten.When dough mixing is excessive,the role of stirring force the dough deep binding water(12%)precipitation into weak bound water(87%)and free water.So that the disulfide bond is broken,?-helix and ?-sheet into irregularcurly and ?-turn,molecular weight glutenin and gliadin polymerization decreases,and ultra-high molecular weight glutenin polymers appear,which destroyed the gluten network(7%).And the change of moisture distribution,protein,starch between the molecular bonds,changes in the process of dough mixing changes the state of the gluten network,which in turn affects the rheological properties of the dough.According to the analysis of the response surface of steamed bread and dough,we can know that the factors of mixing process such as the water content,mixing time and water temperature affect the quality of steamed bread by affecting the properties of dough.Water temperature and mixing time affect the specific volume and internal structure of steamed bread by influencing the holding time,gas production and dough fermentation height of dough.Water content and water temperature determine the specific volume of steamed bread by influencing the ratio of dough's volume decrease and gas production,whiteness.Mixing process by affecting the dough volume change and gas production affects the hardness,chewing of steamed bread.Water temperature affects the bread adhesion by affecting the surface gas production.The relationship between dough stretching and the quality of steamed bread are complex.Dough tensile fracture strength,steamed bread sensory and specific volume are significantly negatively correlated,while the dough stretch distance and sensory evaluation of bread between the quadratic function.Double-drive and double-action mixer can make the raw materials mix faster and make the water reach a uniform state.But the reduction of contact time between agitating shaft and dough will delay the formation of gluten.The faster the mixer running,the faster the dough is formed.However the high speed is not good for the dough forming.It also causes the dough to heat up too much.The yeast starts earlier makes the dough more stomata and damages the gluten network and the starch granules.Compared with the constant speed mixing,positive and negative and variable speed mixing are conducive to raising the dough holding time and gas production.Horizontal mixer has the slowest speed,and the dough forming time is longer,properties of dough and steamed bread are better.But its energy consumption is too large.