Quantitative Characterization Of Water Uniformity Of Noodle Sheet And Its Impact On Noodles Quality

Noodles are a major traditional staple food in China.It is mainly prepared from wheat flour and water as the main raw materials.The major steps involved in the production of noodles are as follows;dough preparation,proofing,rolling,cutting followed by a drying process.The distribution of water in the dough sheet significantly affects the formation of the gluten network and drying process;ultimately affects the quality of the noodles.The traditional quality control methods primarily improves the quality of noodles by varying the process parameters.The purpose of controlling water distribution in noodles is to change the process parameters.Albeit,this method improves the quality of the noodles to a certain extent,it does not provide a specific characteristic parameter to quantify the specific distribution of moisture in the dough sheet,which leads to the enterprises unable to accurately control the quality of noodles.Therefore,in this study,hyperspectral image technology combined with distributional homogeneity index method was used to put forward the water distribution homogeneity as the characteristic parameter.By establishing the relationship between water distribution homogeneity and noodle processing parameters,physical and chemical quality indicators to achieve the purpose of controlling noodle quality.The cardinal achievements realized from this study are summarized as follows::（1）Rapid quantitative characterization of water distribution homogeneity of dough sheet based on hyperspectral imagingHyperspectral imaging technique combined with water distributional homogeneity index method was used for rapid and quantitative characterization of water distribution homogeneity in dough sheet.The spectral signals and physicochemical values of water content of dough sheet were extracted.The pretreatment methods such as SNV,SG,MSC,1^stDER and 2^ndDER were used to acquire the feature spectrum.Thereafter,three multivariate algorithms such as iPLS,BP-ANN,LS-SVM were compared to establish an optimal prediction model.The extracted spectral data of each point of the test piece was used as an input into the optimal quantitative prediction model to obtain the visual distribution map of the water content of the dough sheet.Finally,the distributional homogeneity index method was used to calculate the water distribution homogeneity from the obtained water content distribution map.The acquired results revealed that the SNV pretreatment effectively reduced the background information and noise interference,and significantly improve the accuracy of the built model.LS-SVM yielded optimal prediction model with,Rc=0.99,Rp=0.98,RMSEC=0.01 and RMSEP=0.01.The water distributional homogeneity value calculated by the distributional homogeneity index method corresponds to the results described in the water content distribution map,and the feasibility of determining the homogeneity of water distribution in dough sheet by the hyperspectral imaging combined distributional homogenity index method was verified.（2）Influence of noodle mixing process on water distribution homogeneity of dough sheetThe effects of mixing process parameters such as vacuum,water addition,and mixing time on the moisture distribution uniformity of the noodles dough sheet was studied.The quadratic regression orthogonal rotation combined experimental design was used to investigate the effects of process parameters such as vacuum,water addition and mixing time on the homogeneity of moisture distribution of the dough sheet.The order of influence and the optimum technological conditions of each single factor were determined by variance analysis and response surface analysis.The results showed that vacuum（A）,water addition（B）and mixing time（C）significantly affect the water distribution uniformity of the dough sheet.The results of orthogonal experiment and variance analysis showed that the water distribution uniformity of the dough sheet and the parameters of the dough sheet could be predicted as follows:water distribution homogeneity=2.16+0.55×A+1.13×B+0.91×C+0.85×A×B+0.59×B×C+1.22×A²+0.73×B²+0.63×C²,and R² of the model is 0.90 and the signal-to-noise ratio is 10.09.According to F test in the variance analysis,the order of influence of three factors on the uniformity of water distribution on the patch as follows:the mixing time>water addition>the vacuum,which was consistent with the result of response surface analysis.The optimal processing parameters were observed in this study as follows;vacuum 0.08 MPa,water addition 37%.（3）Effect of water distribution homogeneity of dough sheet on the quality of noodlesThe effects of different water distribution uniformity on the quality of noodles including optimum cooking time,tensile properties,flexural properties,color,cooking characteristics,TPA characteristics and sensory characteristics were evaluated.The noodles with different water distribution uniformity were prepared.The water distribution uniformity and the physical and chemical quality parameters with different water distribution uniformity were measured,and the acquired results were subjected to statistical analysis.The results showed that in the bending resistance,the uniformity of moisture distribution of the dough sheet was negatively correlated with the fracture stress,elastic modulus and displacement.It has no significant correlation with the elastic modulus of the noodle.In the cooking characteristic experiment,the water distribution uniformity of the noodles was positively correlated with the optimum cooking time and cooking loss rate,but negatively correlated with the water absorption rate and ripening broken strip rate.The color analysis recorded that the uniformity of the moisture distribution of the dough sheet was not significantly related to the brightness,but had a positive correlation with the redness and greenness of cooked noodles and a negative correlation with the yellowness and blueness of cooked noodles.The moisture distribution was negatively correlated with hardness adhesive and resilience of cooked noodles,positively correlated with chewiness,but not with other factors.The sensory analysis revealed that the uniformity of different water distribution was negatively correlated with the toughness,viscosity and smoothness of cooked noodles,and no significant effect on the color,appearance,palatability and taste of cooked noodles were observed by the sensory panel.In this work,the relationship between the moisture distribution and the processing parameters of noodles were established by using the moisture distribution uniformity of noodles as the characteristic parameter,which provides a new idea for the automatic control of mixing process.Likewise,the relationship between the moisture distribution uniformity of noodles and the physicochemical quality of noodles were established,which provides an in-depth theoretical basis for the quality control of noodles.