挤压糊化处理对苦荞粉理化性质的影响

Effect of Gelatinization by Extrusion on Physicochemical Properties of Tartary Buckwheat Flour

为研究挤压糊化处理对苦荞粉理化性质的影响,利用单螺杆挤压机对苦荞粉进行挤压糊化处理,得到糊化度分别为37.7%、56.3%、74.3%及94.2%的苦荞粉,并对其基本成分、水合特性、糊化特性、热力学特性及微观结构进行测定。结果表明:随着糊化度增加,淀粉、蛋白质及灰分质量分数总体无显著变化(P>0.05),总黄酮和脂肪质量分数显著减少(P<0.05),颜色变深;破损淀粉质量分数、吸水性指数及保水性显著增加(P<0.05);快速黏度分析结果表明挤压处理苦荞粉峰值黏度、谷值黏度、最终黏度、回生值下降,峰值时间缩短;扫描电子显微镜结果表明,苦荞粉颗粒为圆形或不规则多边形,而挤压糊化处理后苦荞粉颗粒没有固定形态,表面粗糙且有裂纹和小孔。上述理化性质的研究可为进一步的机理及应用研究提供参考。

In order to study the effect of gelatinization by extrusion on physicochemical properties of tartary buckwheat flour, four different gelatinization degree of tartary buckwheat flour, 37.7%, 56.3%, 74.3% and 94.2%, were obtained by a single-screw extruder, and the major chemical constituents, pasting properties, hydration properties, thermodynamic properties and microstructure of the extruded flours were determined. The results showed that the contents of total flavonoids and lipids in flour reduced significantly（P〈0.05） and the color of flour became darker with the increase of gelatinization degree, while the contents of starch, ash and protein showed no significant change（P〈0.05）. The proportion of damaged starch, water absorption index and water retaining capacity increased significantly（P〈0.05）. The rapid viscosity analyzer analysis indicated that peak viscosity, trough viscosity, trough viscosity, final viscosity, setback, and peak time declined after extrusion. Scanning electron microscope observation showed that tartary buckwheat flour appeared as round or irregular polygon starch granules with smooth surface, while the extruded flour had no definite shape and the surface became rough with cracks and holes. To conclude, the above results provide useful data for insights into the underlying mechanism and for the application of extruded tartary buckwheat flour.