Effects Of Different Processing Techniques On The Quality And Digestibility Of Rice Noodles

Rice noodles are characteristic traditional foods in southern China.It is very popular among consumers because of its flexible texture and good taste.The quality and nutrition of rice noodles are important factors that determine their commodity value and market demand.From the processing point of view,there are many factors that affect the quality of rice noodles,including the preparation of raw materials,pasting properties,the addition of other raw and auxiliary materials.The production and processing of rice noodles is a complicated process.These factors also affect the digestibility and glycemic index(GI)of rice noodles.Medium and low GI foods,especially staple food products such as rice noodles,are of great significance to diabetics.At present,there is still insufficient research on the effects of different processing methods of rice noodles on their quality and digestion characteristics.Therefore,the goal of this study is high-quality,low-GI rice noodles,carried out the raw material processing of rice flour processing,extrusion process,and the addition of pea flour accessories,etc.,in order to obtain the rice noodle products with low GI characteristics and related production technologies.This can provide technical reference for the development of the rice noodle industry in the direction of nutrition and health,and meet people's urgent needs for slow digestion or low GI staple food products.The results were showed as followed:(1)The effects of four methods of milling,including wet milling,dry milling,semi-dry milling and jet milling on the physical and chemical properties of rice flour were compared.The results show that different milling methods have a significant effect on the particle size of rice flour and the degree of starch damage(p<0.05).By comparing the pasting properties,thermal properties and gel properties of the four flour,it was found that the properties of the semi-dry milling flour are closest to those of the wet milling flour.At the same time,it was found that the mechanical force and milling methods did not destroy the crystalline structure of rice starch,which was still A-type crystal.According to the texture and tensile properties of the rice noodles,there was no significant difference in adhesiveness,springiness,resilience,breaking distance and tensile work of the rice noodles prepared by the semi-dry flour and wet milled flour(p>0.05).Combining the quality of the rice noodles and the convenience of the operation,the semi-dry method is determined as the main method for preparing the rice raw material flour.the jet milling flour has a small particle size,which is suitable for the later processing of pea-rice noodles.Comparing the effects of different milling methods on the digestibility of rice flour and rice noodles,it was found that the milling methods had a significant effect on the digestibility of rice flour(p<0.05).The digestion rates of wet milled flour K and eGI were 3.08 and 85.30 respectively,and the corresponding of jet milling flour was 3.32 and 99.27.However,different milling methods had no significant effect on the digestibility of the final product rice noodles(p>0.05).(2)The effects of extrusion processing conditions(temperature,moisture content of raw materials,screw speed)on the quality characteristics and digestibility of extruded rice flour were compared.It makes the color and crystal structure of the extruded rice noodles change,and the crystallinity decreases.Combining the cooking quality,sensory evaluation,texture,and tensile of rice noodles,it was found that the quality of extruded rice noodles was better under the conditions of an extrusion temperature of 95 ?,a moisture content of 35%,and a rotation speed of 120 rpm.The extrusion temperature affects the degree of gelatinization of rice noodles and affects its digestibility,but the moisture content and screw speed have no significant effect on the digestibility of rice noodles(p>0.05).(3)The addition of whole pea flour to the rice noodles increases the nutritional quality of the rice noodles and also has a greater impact on their eating quality.With the increase of the amount of pea flour,the hardness,adhesiveness,chewiness and resilience of rice noodles increased.The addition amount of pea flour was 15% and 30%,the cooking loss of rice noodles was 10.04% and 14.63%,respectively;sensory evaluations were 85.47 and 79.27,respectively.The addition of pea flour makes the color and brightness of rice noodles lower.The pea-rice noodles can be accepted by consumers without affecting consumption.Comparing the particle size of the added pea flour,it is found that when the amount of the pea flour added is the same,the pea flour with a small particle size has little effect on the cooking quality and overall sensory of rice noodles.By reducing the particle size of pea flour,high-quality pea-rice noodles with a pea flour content of 30% are produced.Adding pea flour significantly reduced the gelatinization of rice noodles.With 30% pea flour added,the eGI of rice noodles reaches 62.14,which is 26.32% lower than that of no added samples,making it possible to prepare low GI rice noodles.