挤压处理对淀粉结构与糊化性质的影响

Effect of extrusion treatment on starch structure and gelatinization properties

以不同直链淀粉含量(AC)的粳米淀粉、木薯淀粉、玉米淀粉、豌豆淀粉为原料,使用双螺杆挤压膨化试验机制备样品。使用快速黏度分析仪(RVA)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、凝胶色谱-示差-多角度激光光散射(GPC-RI-MALS)测定挤压前后样品黏度和结构变化。结果表明:挤压淀粉样品的峰值黏度、崩解值、最终黏度和回生值显著低于天然淀粉(P<0.05),说明凝胶稳定性提高,短期回生减少。在挤压过程中淀粉吸水膨胀,颗粒完整性遭到破坏。淀粉糊化性质变化可以用分子结构特征来解释,特别是分子尺寸大幅度减小和多分散性增加。天然淀粉中直链淀粉含量不同,其结果变化有显著性差异(P<0.05),表明挤压淀粉糊化性质变化与结构密切相关。

Rice starch,cassava starch,maize starch and pea starch with different amylose contents were used as raw materials to prepare the samples by using a twin-screw extrusion tester.Rapid viscosity analyzer(RVA),scanning electron microscope(SEM),X-ray diffractometer(XRD)and gel chromatography-differential multi-angle laser light scattering(GPC-RI-MALS)were used to determine the viscosity and structural changes of the samples before and after extrusion.The results showed that,the peak viscosity,breakdown,final viscosity and setback of extruded starch samples were significantly lower than those of natural starch samples(P<0.05),indicating that gel stability was improved and short-term recovery was decreased.During the extrusion process,starch absorbd water and expanded,then particle integrity was destroyed.The change of gelatinization properties can be explained by the molecular structure characteristics,especially the large reduction of molecular size and the increase of polydispersity.The content of amylose in natural starch was different,and the difference of the results was significant(P<0.05).The results indicated that the gelatinization properties of extruded starch were closely related to the structure.