Study On The Water State And Distribution Of Chinese Dried Noodles During Drying Process

The effect of the drying process in Chinese dried noodles?CDN?making is affected by the mixing process.The migration and change of the moisture in the CDN drying process will cause changes in the internal stress.Inappropriate production process will lead to some quality problems.The effects of Processing parameters on the drying characteristics and product characteristics of the noodles and the distribution of moisture in the noodle drying process were systematically studied.This could provide the basis for the design of noodle production process,the automatic adjustment of the process parameters and the energy saving and consumption of the noodle.In this study,wheat flour was used to make CDN.A noodle processing experiments of three factors was designed?water addition 30%,35%;and vacuum degree 0.00MPa,0.06Mpa;drying temperature 32??40??48??.moisture analysis system for food was used to dry noodles and analysis drying characteristics.The sample time was 45min with low-field nuclear magnetic resonance to measure the spin-spin relaxation time?T₂?and the proportion of peak integral areas?A₂?.Texture profile analysis?TPA?and Chroma meter were used to investigate the quality characteristics of CDN.We uesd Yongliang No.4 wheat flour to make round noodles with extrude.The water distribution of the round noodles during drying process was obtained by the low field magnetic resonance imaging.The influence of water addition,vacuum degree,drying temperature and its interaction on the drying characteristics,product characteristics,water state?transverse relaxation time and the ratio of the three water peaks?were systematically investigated.The nuclear magnetic imaging data were analyzed by ImageJ software,The contour map and three-dimensional distribution map of water content in noodle were obtained by Matlab software.The theory of moisture distribution at each time of CDN drying is proposed.The main conclusions in this paper are as follows:?1?Water addition was the most important factor affecting the drying process and quality properties,followed by drying temperature;factor interaction has a greater impact on product characteristics.The vacuum degree had no significant effect on the drying characteristics,but had significant effect on the bending distance.The interaction between the vacuum degree and the water addition had an effect on the noodle product characteristics.The increase of water content can significantly increase the bending distance and bending work of CDN.When the drying temperature is raised,the bending distance of the noodle will increase first and then decrease.?2?LF-NMR can provide technical mean for the study of CDN drying process.The factors influencing the T₂ of CDN during drying process were in descending order:water addition,drying temperature,vacuum degree;the factors affecting the A₂ of three kinds water during drying process were in descending order:water addition,vacuum degree,drying temperature.?3?The contour of CDN sample soaked in soybean oil was clearer than without soybean oil.CDN sample soaked in soybean oil was also helpful to improve the signal-to-noise ratio of the image.The shrinkage of CDN during the drying process and the existence of the central crack could be observed with the soybean oil.?4?The establishment of the moisture content gradient during the CDN drying process was gradual.The moisture content gradient from the center to the edge in the noodles established after drying for 90min.The internal?0¹50min?moisture content distribution function can be described by:W=Wcenter-?Wcenter-Wedge?/R2x2.