Influence Of Different Mixing Methods On The Rheological Properties Of Dough And Noodle Quality

In this study,we used the plain flour as the raw material to analyze different ways of water and flour addition,as well as mixing machines,and their influence on rheological properties of dough and noodle quality were analyzed and compared.The paper used some technical means such as Low-field Nuclear Magnetic Resonance,Confocal Laser Microscopy,Texture Profile Analysis and Rotational Rheometer to compare effects of different methods of water and flour addition,as well as mixing machines on water distribution state,rheological properties(uniaxial and biaxial tensile properties,stress relaxation and creep-recovery characteristics),microstructure of dough and noodle quality.The main results are as follows:(1)Change the way of water addition,moisture distribution and rheological properties of dough changed significantly.Compared with the dough made by adding all water to flour(A-1),water free degree of dough(A-2,A-3,A-4,A-5)by adding all water to flour by many times were weaker,water holding capacity stronger,and the maximum tensile and tensile area of dough increased significantly,but the difference between tan? was little,the values of K and n changed,and there were obvious differences in viscoelasticity of doughs.Their microstructure was observed by CLSM,we found that gluten protein more closely associated with starch,starch granules more absorbent and expanded.This indicated that adding water to flour by many times could promote the interaction of water and protein,starch in flour,and improve the dough quality.(2)Change the way of flour addition,moisture distribution and rheological properties of dough changed significantly.Compared with the dough(A-1)made by adding all water to flour,the ability to bind water of dough(B-1)made by adding all flour to water was poorer,the water holding capacity of the dough which was made by adding flour for many times(B-2,B-3,B-4,B-5)were enhanced,tensile properties and viscoelasticity improved significantly,the elasticity increased and viscosity decreased.Nevertheless,using CLSM to observe their microstructure,we found that gluten network structure of doughs did not show obvious changes,in which the doughs(B-4 and B-5)which when the amount of flour added to water was less,gluten network were more tightly bound to starch.(3)There were significant differences in dough characteristics of different mixing equipment.The dough maded by vacuum mixer showed strong water holding and tensile properties,relaxation modulus was the largest,creep compliance smallest,elasticity best,while viscosity smallest.In addition,using CLSM to observe their microstructure,we found that gluten network of this dough made by vacuum mixer was more closely combined with starch granules,and the continuity of gluten better,comparing with other two doughs,The dough,which was processed by pin mixer,was the opposite,and characteristics of dough prepared by spiral mixer was in the middle.This phenomenon may be closely related to the type of stirring knife and the strength of the mixing equipment.Furthermore,the moderate vacuum could accelerate the water penetration into the flour particles,reducing the loss of moisture,promoting the uniform water absorption of protein and starch,reducing the flow of water molecules,and making the gluten network more fully formed.(4)The quality of noodles made by different mixing ways were determined.Compared with the noodle made by adding all water to flour,when adding water to flour or adding flour to water,the water absorption and expansion of starch of noodles were more sufficient,the transparency of noodles were enhanced and there were relatively white.After cooking,The water absorption of noodles increased significantly,but the loss of cooking was not significantly different.The tensile strength of noodles made by different mixing methods increased.And,the difference between the results of TPA determination mainly embodied in the hardness of noodles,yet the elasticity,cohesiveness and chewiness of noodles had no significant difference.The total sensory scores of all noodles were above 84 points,and the acceptable degree were higher.The overall quality of noodle made by vacuum mixer was better.This might be closely related to the closed low oxygen environment formed by vacuum and flour machine.In conclusion: Distinguished from traditional dough modulation method,change the way of adding water or flour would improve the degree of combination of flour and water,and viscoelasticity of doughs could be improved to a certain extent.The lubrication of water could change the relative sliding capacity of the polymer molecules in the dough,which might be the main reason for the viscoelasticity difference of doughs.On the whole,the dough processed by three times of adding water or three times flour had better rheological properties and good noodle quality.In addition,there were great differences in the mixing effects of three mixers,and the quality of dough and noodle made by different surface equipment was quite different.Under certain conditions,vacuum and flour machine was better.