Optimization Of Selenium-enriched Germinated Brown Rice And Its Extruded Rice

In this experiment,common brown rice was used as raw material to make selenium-enriched germinated brown rice with high germination rate and organic selenium content,and then selenium-enriched germinated brown rice with high comprehensive score was extruded by twin-screw extrusion mechanism.The quality of extruded rice was studied,and the effects of selenium-enriched germination and extrusion on the quality of brown rice were analyzed.First of all,the optimum culture conditions of selenium-rich germinated brown rice were studied.Ordinary brown rice was selected as raw material,germination rate and organic selenium content were taken as indexes,germination temperature,germination time and mass concentration of sodium selenite were taken as factors.Through single factor experiment and response surface experiment,the optimum culture conditions of selenium-enriched germinated brown rice were obtained as follows: soaking time 16 h,soaking temperature 30℃,germination time 31 h,germination temperature 32℃,sodium selenite concentration 15mg/L.Through the verification experiment,the germination rate is 81.7%,and the selenium-rich germinated brown rice with organic selenium content of 1.661mg/kg is close to the predicted value.Then,the optimum extrusion conditions o f selenium-enriched germinated brown rice were studied,and the selenium-enriched germinated brown rice was made into extruded rice.The comprehensive score was taken as the investigation index,and the extrusion temperature,water addition,screw speed,f eed speed and cutter speed were taken as factors.Through single factor experiment and response surface experiment,the optimum extrusion conditions of selenium-enriched germinated brown rice were obtained as follows: extrusion temperature 117℃,water addition 21%,screw speed 107r/min,feed speed 14kg/h,cutter speed1100r/min.Through the verification experiment,the extruded rice of selenium-enriched germinated brown rice with a comprehensive score of 85.5 was obtained,which was close to the predicted v alue.At the end of the experiment,the selenium-rich germinated brown rice extruded rice has good appearance and good taste.Finally,the quality of selenium-enriched germinated brown rice extruded rice was determined,and its nutrient content,physicoch emical index,texture determination,rapid viscosity analysis(RVA),differential scanning calorimetry(DSC)and X-ray diffraction(X-RD)were carried out.Compared with ordinary brown rice,common brown rice extruded rice and selenium-enriched germinated brown rice,the results showed that selenium-rich germination increased the protein content of brown rice.The content of starch and fat decreased,and the protein content,starch content and fat content of brown rice decreased by extrusion.Selenium-enriched germination and extrusion decreased the bulk density of brown rice and increased the water absorption and water solubility of brown rice.The texture results showed that extrusion increased the hardness,elasticity and chewiness of brown rice,while selenium-enriched germination decreased the hardness,elasticity and chewiness of brown rice.RVA results showed that selenium-enriched germination and extrusion could reduce the peak viscosity,lowest viscosity,disintegration value,final viscosity and ret rogradation value of brown rice.DSC results showed that selenium-enriched germination and extrusion decreased the enthalpy of gelatinization of brown rice.The X-RD results showed that selenium-enriched germination had little effect on the crystallization properties of brown rice.Extrusion made the brown rice crystal form change from A-type to V-type,the crystallinity decreased and part of the crystal structure was destroyed.