Influence Of Wheat Quality Traits And Their Interactions On The Qualities Of Lanzhou Hand-Stretched Noodles

To research the impact of wheat flour quality traits on Lanzhou hand-stretched noodles(LZHSN)quality,and analyze the change of protein content,composition and structure in the process of making noodles,as well as study the relationship between protein changes and the cooked noodles quality could provide scientific basis for tailored flours standard setting and production,and also could improve the quality of noodles.In this study,wheat cultivars which grown in Huang-huai wheat area were chosen as the experimental materials.The noodle was processed with the same process procedure and compounding recipe by one master who had many years experience.The professional master made evaluations during processing and the sensory evaluation team evaluated cooked noodles.Correlational analysis,regression analysis,path analysis,cluster analysis and variance analysis were used to screen the indexes which affect the quality of LZHSN,and the quality requirement of LZHSN on wheat flour quality traits was proposed.On the basis of above,in order to study the formation mechanism of Lanzhou hand-stretched noodles quality,three different wheat varieties which had large quality difference were chosen as experimental materials to make noodles.The change of protein content,composition and structure in LZHSN production process was analyzed and discussed.The relationship between the protein changes and the sensory quality of LZHSN was explored.The main conclusions in this paper were as follows:(1)Protein content,wet gluten content,water absorption,weakening degree,resistance to extension and extension energy were the main protein properties of wheat flour that affect the LZHSN processing.The‘degree of mixing and hardness of dough',‘slitting effort by hand and stickiness',‘extending force'and the‘total score of processing procedure'were the main indexes that might be influenced.Protein content,wet gluten content,weakening degree and extensive energy were the main protein properties of wheat flours that affect the cooked LZHSN,these index mainly affects the‘color',‘surface',‘hardness'and‘total score of sensory evaluation'of cooked noodles.(2)Peak viscosity and breakdown were the main starch properties of wheat flour which mainly affect‘degree of mixing and hardness of dough'‘dough color after resting'‘force to stretching'and‘total score of processing procedure'in LZHSN processing.Cooked noodles were mainly influenced by the breakdown of wheat flour.Breakdown mainly affect the‘hardness',‘surface'and‘total score of sensory evaluation'of the noodles.(3)Chroma meter could be used to predict the color of LZHSN.Ash content,color(L*value and a*value),protein content,wet gluten content and pasting temperature were the main indexes that had great influences on the color of the noodle.High quality of LZHSN should have higher L*value and lower a*value,and the noodle color should be yellow or bright yellow.(4)The ideal quality of Lanzhou hand-stretched noodles required:color a*rangs from-1.8 to-1.6,protein content between 12.0%~13.0%,wet gluten content between 28%~30%,damaged starch content between 18.0~22.0 UCDc,extension energy between 40~50 cm~2,and also a higher peak viscosity(?490BU)and lower breakdown(?80 BU).(5)The gluten network structure was formed,completed and further homogenized during the process of making LZHSN.The protein mixed with water could form gluten network structure in the beginning of mixing;and then protein inside the dough was re-depolymerization and polymerization during resting,which made the internal stress becomed relax and the ductility increase;the structure of the gluten network was constantly adjusted because of the external force and reached a certain steady state;during the cooking process,the protein was denatured,the starch was partially gelatinized,and the gluten network structure disappeared during the cooking process.Proteins with different molecular weight inside the dough were in a dynamic adjustment state in the whole process of making LZHSN.From mixing to stretching,the LMP content and free-SH content increased,and GMP content decreased;and the second structure composition of protein would be changed because of the external force;the change of protein composition and structure was a necessary condition for the formation of uniform and stable gluten network.The protein composition and structure presented differently in the process of making noodles among different wheat flours,which would affect the rheology characteristics of dough in the process,and thereby affected the overall evaluation of the master on the quality of flour or the applicability of the quality traits of wheat flour.The protein quality had more influences on the process procedure than on the cooked noodle quality.