Study On The Improvement Of Quality Characteristics Of Extruded Brown Rice Noodles

Brown rice is a typical example of whole grains,and it has higher nutritional value and much better content of bioactive ingredients than milled rice.Using brown rice as raw material to produce noodles can not only meet the market demand of consumers for nutritious staple food,promote the process of whole grain staple food,but also facilitate the efficient utilization of rice resources.However,due to the existence of bran,the cooking quality of brown rice noodles is not good,it possesses high breaking rate and cooking loss,and the poor palatability.These defects seriously limit the development of brown rice noodles.Based on this,this study used extrusion technology to prepare extruded brown rice noodles,studied the effects of different milling methods on the quality characteristics of brown rice flour and extruded brown rice noodles,and then improved the quality of extruded brown rice noodles through physical modification methods such as heat-moisture treatment,ultrasonic-parboiling treatment.The research results are as follows:1.The effects of different milling methods on the quality characteristics of brown rice flour and extruded brown rice noodles were investigated.The results showed that compared with dry milling,semi-dry and wet milling resulted in smaller particle size,lower damaged starch content,water solubility index and higher L* value of brown rice flour.In addition,the semi-dry and wet milled brown rice flour had higher pasting viscosity,setback value and gelatinization enthalpy.The semi-dry and wet milling significantly enhanced the viscoelasticity of the brown rice paste,improved the cooking quality of the extruded brown rice noodles,and reduced the breaking rate from 13.33% to 1.67%,and the cooking loss from 14.53% to 7.10%.Meanwhile,extruded brown rice noodles made by semi-dry and wet milling had higher hardness,cohesiveness,chewiness,and lower adhesiveness.In terms of variety selection,indica rice variety was more suitable for preparing extruded brown rice noodles because of its lower damaged starch content,higher pasting viscosity and setback value,and stronger viscoelasticity of paste.Extruded brown rice noodles made from indica rice had higher hardness,chewiness and lower adhesiveness.2.The effects of heat-moisture treatment on the quality characteristics of brown rice flour and extruded brown rice noodles were investigated.Heat-moisture treatment promoted the formation of amylose-lipid complex,and the crystal structure of brown rice flour changed from type A to type A+V.With the increase of temperature and moisture content,crystallinity and amylose content of brown rice flour increased significantly.The water solubility index,swelling power,pasting viscosity and breakdown value of brown rice flour were significantly reduced by this treatment,and the storage modulus and loss modulus were increased.As for the extruded brown rice noodles after heat-moisture treatment,the microstructure became uniform and dense,the breaking rate and cooking loss decreased significantly,the hardness,springness and cohesiveness increased,and the adhesiveness decreased significantly.When the treatment temperature was 80℃ and the moisture content was 20%,the breaking rate and cooking loss of extruded brown rice noodles were the lowest,which were 1.75%and 9.88% respectively.In addition,heat-moisture treatment could reduce the in vitro starch digestibility of extruded brown rice noodles,decrease the predicted glycemic index(p GI)from 78.42 to 69.29,and increase the ratio of resistant starch(RS)from28.50% to 41.82%.However,as the moisture content of heat-moisture treatment further increased(25%),the quality improvement effect of heat-moisture treatment on the extruded brown rice noodles was weakened.In conclusion,heat-moisture treatment was helpful to improve the quality of extruded brown rice noodles.3.The effects of ultrasonic-parboiling treatment on the quality characteristics of brown rice flour and extruded brown rice noodles were investigated.The results showed that the main crystal type of brown rice flour was still type A after ultrasonic-parboiling treatment,but with the enhancement of ultrasonic treatment condition,the intensity of the diffraction peak of amylose-lipid complex in the XRD pattern increased significantly.Ultrasonic treatment resulted in the decrease of pasting viscosity and breakdown value of brown rice flour.Ultrasonic-parboiling treatment improved the viscoelasticity of brown rice paste,gel hardness and cohesiveness,and reduced the gel adhesiveness.Parboiling treatment led to the decrease of total phenol content and antioxidant activity of brown rice flour.The application of ultrasonic technology and the raising of ultrasonic frequency increased the total phenol content and DPPH radical scavenging ability from 91.91 mg GAE/100 g and 823.34 μmol TE/g to 108.08 mg GAE/100 g and 893.68 μmol TE/g,respectively.The application of ultrasonic-parboiling technology and the increase of ultrasonic frequency significantly reduced the breaking rate and cooking loss of extruded brown rice noodles,and significantly improved its texture and starch digestion characteristics.When the ultrasonic frequency was 500 W and the treatment time was 15 min,the breaking rate and cooking loss were the lowest,which were 0% and 9.43%,respectively.When the ultrasonic frequency was 500 W and the treatment time was 30 min,the hardness of extruded brown rice noodles was the highest(4094.03 g),the p GI decreased to 65.66,and the RS content increased to 44.84%.The above results reflected the effectiveness of ultrasound-parboiling treatment in improving the cooking and texture characteristics,and reducing the starch digestibility of extruded brown rice noodles.