不同品种紫薯淀粉结构与其面团品质的关系

Relationship between Starch Structure and Dough Quality Characteristics of Different Varieties of Purple Sweet Potato

本文以紫薯淀粉为对象,研究其微观结构、晶体特性、粒径分布、紫薯淀粉-小麦粉面团的粉质、糊化、流变特性及水分分布状态、淀粉结构与面团之间的相关性。结果表明:紫薯淀粉颗粒呈圆形和半球形,平均颗粒范围43.903~55.842μm,体积呈三峰型分布,X衍射表明绝大多数紫薯淀粉为CA型,结晶度36.76%~54.28%。紫薯淀粉面团的形成时间、稳定时间范围分别在2.20~3.90 min和3.20~4.10 min。糊化温度升高,在70.10~85.65℃范围,其它糊化特性降低,有利于面团的稳定性。储能模量(G')、损耗模量(G'')显著增加,损耗角正切值(tanδ)先下降后上升,表明混合体系中分子交联的程度增加,使面团有弹性,而水分分布状态存在差异。相关性分析表明,结晶度与吸水率、稳定时间、弱化度、公差指数、糊化温度呈负相关,与峰值黏度、顶点时间、最低黏度、最终黏度、回生值呈现正相关。平均粒径与弱化度、衰减值呈负相关,与顶点时间、结晶度呈正相关。本研究结果为淀粉的选择和淀粉面团生产专用的紫薯品种的栽培提供了理论基础。

In this paper,the microstructure,crystal properties and particle size distribution of purple sweet potato starch and its dough were studied,Farinograph,RVA and rheological properties of purple sweet potato starch-wheat flour dough were analyzed,and the correlation between starch and dough was analyzed.Starch granules of purple sweet potatoes all exhibited round and hemispherical shapes.The average particle range was 43.903 to 55.842μm,and the volume distribution was three-peak distribution.X-ray powder diffraction patterns revealed purple sweet potato starches were CA-type with relative crystallinity varying from 36.760%to 54.280%.The formation time and stabilization time of purple sweet potato starch dough were in the range of 2.20~3.90 min and 3.20~4.10 min,respectively,and other gelatinization properties decreased with the increase of gelatinization temperature between 70.10℃to 85.65℃,which was beneficial to the stability of dough,the storage modulus(G')and loss modulus(G'')increased significantly,while the loss angle tangent(tanδ)decreased first and then increased,indicating that the degree of molecular cross-linking in the mixed system increased,which made the dough elastic and beneficial to the stability of dough.There were differences in water distribution.The correlation results showed that the crystallinity was negatively correlated with water absorption,stabilization time,weakening degree and tolerance and pasting temperature,and positively correlated with peak viscosity,peak time,minimum viscosity,final viscosity and retrogradation value.The average particle size was negatively correlated with softening and BV,positively correlated with peak time and crystallinity.This study provides a theoretical basis for the selection of starch and the cultivation of purple potato varieties special for starch dough production.