紫糙米粉挤压工艺优化及其理化性质分析

以紫糙米粉为原料，通过响应面分析法优选紫糙米粉的挤压工艺，利用黏度测定仪（RVA）、X-射线衍射（XRD）、扫描电镜（SEM）表征挤压前后紫糙米粉的糊化特性、结晶特性及微观结构的变化。结果表明:挤压温度147 ℃，水分含量18%，螺杆转速27 Hz，进料速率18 Hz，测得样品的WSI为11.32%、糊化度为93.15%、花色苷含量为97.38 mg/100 g，综合评分为92.43。与原料粉相比，该条件下制备的挤压膨化紫糙米粉，峰值黏度、低谷黏度、衰减值、最终黏度、回生值均显著降低（P<0.05）。挤压膨化后紫糙米粉的淀粉晶体结构由A型转变为V型，结晶度下降；紫糙米粉表面变得光滑，呈现出较多的孔洞结构。表明挤压膨化技术能显著改善紫糙米粉的糊化性质与水化特性，为紫糙米即食代餐粉产品开发提供理论与技术参数依据。

Optimization of Extrusion Process of Purple Brown Rice Flour and Its Physicochemical Properties

Using purple brown rice as raw material, the process parameters of twin-screw extrusion was studied buy the response surface method, and the changes of gelatinization characteristics, crystal characteristics and microstructure of purple brown rice flour before and after extrusion were characterized by RVA, XRD and SEM. Results showed that: The optimization of the extrusion process parameters about purple brown rice flour were extrusion temperature 147 ℃, moisture content 18%, screw speed 27 Hz and feed rate 18 Hz, the WSI of the sample was 11.32%, the gelatinization degree was 93.15%, the anthocyanin content was 97.38 mg/100 g, and the comprehensive scorse was 92.43. Under this extrusion condition, compared with the raw materials, the peak viscosity, lowest viscosity, attenuation value, final viscosity and retrogradation value of the extruded purple brown rice flour decreased significantly (P<0.05). The result showed that the starch crystal structure of extruded purple brown rice flour changed from A type to V type, and the crystallinity decreased. The surface of purple brown rice flour becomes smooth, showing more pore structure. The research showed that the use of extrusion technology could better improve the gelatinization properties and hydration characteristics of purple brown rice flour, and provide theoretical and technical parameter basis for the development of purple brown rice instant meal replacement flour products.