Study On The Effect Of Different System Flours On The Processing Adaptability And Oil Content Of Fried Dough Sticks

Fried dough sticks are a traditionally fried product in China,which has a deep cultural heritage and a broad consumer market.A special flour for fried dough sticks has been emerging in the market.With the pursuit of healthy diet,the development of special flour for low-fat fried dough sticks is getting more and more attention.In this project,20 systemic flours taken from wheat flour production line were used as raw materials,and their adaptability to fried dough sticks processing and the intrinsic connection between wheat flour quality and fried dough sticks quality were firstly analyzed and studied,and then the relationship between wheat flour protein and its subcomponents and fried dough sticks’oil content was investigated in depth from macroscopic and microscopic perspectives to form a comprehensive evaluation of fried dough sticks’oil content.The main findings were as follows:1.Study on the quality of wheat flour and fried dough sticks in different systemsThe differences in quality between different system flours and fried dough sticks were studied in comparison to clarify the correlation between fried dough sticks quality and wheat flour quality.The fried dough sticks made by the front break grinding were chewier but harder and lacked a fluffy texture,while the fried dough sticks made by the back break grinding showed a higher specific capacity.The slag mill flour and tail mill flour lacked the elasticity of the dough,resulting in the formation of fried dough sticks with small specific capacities and excessive hardness and brittleness.Correlation analysis showed that fried dough sticks quality(sensory quality and specific volume)was significantly negatively correlated with water absorption of wheat flour and significantly positively correlated with maximum tensile resistance;water absorption was significantly negatively associated with maximum tensile resistance(r=-0.873).Among them,the primary influence of water absorption was the broken starch of wheat flour(r=0.864),and the effect of maximum tensile resistance was mainly the settling value of wheat flour(r=0.750)and broken starch(r=-0.805).2.Comprehensive evaluation of quality indexes of wheat flour and fried dough sticks based on principal component analysis and cluster analysisMathematical statistical methods such as principal component analysis and cluster analysis were used to identify and classify wheat flour and fried dough sticks,and to determine the processing suitability of wheat flour for fried dough sticks.Four principal components could be extracted by analyzing the quality characteristics of different flour systems,with a cumulative variance contribution of 88.493%and a comprehensive score model of F=0.454F1+0.386F2+0.100F3+0.063F4.Four principal components can be extracted from the PCA of the quality of fried dough sticks,the cumulative variance contribution rate was 84.045%,and the comprehensive score model was f=0.317f1+0.308f2+0.234f3+0.141f4.Cluster analysis at a Euclidean distance of 15.0clusters the 20 different system flours into three major classes.Category 1 contained 1B,2B,1Mc～4M,1S,2S,1T,D1,D2,and DF1;the overall processing quality of wheat flour was poor,while the quality of fried dough sticks was relatively good.Category 2 contained5M～7M,2T,and DF2,the overall processing quality of wheat flour was good,but the quality of fried dough sticks was poor.Category 3 contained 3B,4Bc,and D3,showing relatively excellent wheat flour processing and fried dough sticks quality.Therefore,Class 3wheat flour was the most suitable for the production of fried dough sticks,and the quality characteristics of Class 3 wheat flour can be used as the main data reference for low-fat fried dough sticks special flour:ash content 0.59%～0.85%,crude protein 14.12%～16.25%,wet gluten content 38.51%～44.26%,damaged starch 21.96 UCDc～26.21 UCDc,SIG6.37%～7.23%,sedimentation value 30.56 m L～34.91 m L,water absorption 58.36%～62.37%,flour quality index 211.10 mm～445.56 mm,tensile curve area 161.12 cm~2～197.88cm~2,tensile ratio 2.39(EU/mm)～2.88(EU/mm),tensile resistance 300.29 EU～349.04 EU,elongation 208.51 mm～247.49 mm,maximum tensile resistance 554.01 EU～634.99 EU.3.Study on the correlation between rheological properties of mixed dough and oil content of fried dough sticksThe results revealed that the extended gluten protein membrane structure in the gluten structure was an excellent barrier to oil intrusion and reduced the internal structural oil of the fried dough sticks.In addition,this structure conferred weak elasticity to the dough,resulting in improved deformation tolerance.The Principal Component Analysis(PCA)results also showed that the fried dough sticks’oil content was negatively correlated with formation time,stabilization time,and maximum creep flexibility and positively associated with dough stiffness and steady-state viscosity.To some extent,the two compounding schemes of FP-5and FP-6 with 42%wet gluten content induced a better network structure of the dough to form an extended gluten protein membrane.4.Study on the effect of gluten components on the molecular mechanism of reconstituted dough and the oil content of fried dough sticksThe three components of protein,starch and water-soluble substance with higher purity were separated from the raw flour by separation and recombination.The ratio of gliadin and glutenin was adjusted to formulate into model flour,and then the model flour was mixed with raw flour at 1:1 to formulate into reconstituted flour to explore the effect of gliadin/glutenin(Gli/Glu)ratio on the functional and structural properties of reconstituted dough.It was found that gluten proteins with Gli/Glu ratio 5:5 formed a stable gluten network structure that could effectively reduce oil intrusion and hinder the exposure of hydrophobic groups,where the hydrated-β-sheets structure provided a positive effect and the antiparallel-β-sheets structure produced the opposite effect.The network structure of gluten proteins with a higher percentage of gliadin than glutenin tended to be looser,which increased the exposure of chromogenic groups and led to a large amount of oil intrusion due to the change of spatial network conformation.In addition,the increased content of gliadin made the gluten network structure require more ionic bonds,hydrogen bonds,hydrophobic interactions and covalent bonds to maintain its stability.This study provided the theoretical basis for selecting flour for low-fat fried dough sticks,product quality improvement and production of special flour.