扬麦29和苏裸麦2号的淀粉特性比较

Comparison of Starch Characteristics Between Yangmai 29 and Suluomai No.2

本研究以小麦品种扬麦29和元麦品种苏裸麦2号为试验材料,在成熟期测定其直链淀粉和支链淀粉含量,并分别提取淀粉,观察和比较两者的淀粉粒形态和数量、体积、表面积分布特征以及淀粉糊化特性(RVA)、热力学特性(DSC)、晶体结构和链长分布。结果表明,苏裸麦2号总淀粉和支链淀粉含量均显著低于扬麦29,直链淀粉含量差异无统计学意义。扬麦29的A型淀粉表面有明显的“赤道槽”,苏裸麦2号B型淀粉的团聚现象更为明显。2份材料淀粉粒的数量和体积呈微弱的双峰分布,表面积为双峰分布,胚乳淀粉基本由C型淀粉粒组成,总体积主要取决于A型淀粉粒,A型淀粉粒表面积占比超过50%。其中苏裸麦2号C型淀粉粒数量、体积和表面积占比大于扬麦29,而A型和B型淀粉粒趋势与之相反。苏裸麦2号淀粉的峰值黏度、最低黏度、崩解值、峰值时间均显著高于扬麦29,最终黏度与回生值则呈相反趋势。热力学参数和热焓值总体呈现扬麦29高于苏裸麦2号的趋势。2份材料淀粉晶体结构均为典型的A-型晶体结构,且苏裸麦2号的结晶度高于扬麦29。支链淀粉链长受短链的影响程度相对较大,其中扬麦29的支链淀粉短链部分,即聚合度为6~12所占的相对比率要高于苏裸麦2号。

In this study,wheat cultivar Yangmai 29 and Yuanmai cultivar Suluomai No.2 were used as experimental materials.The contents of amylose and amylopectin were determined at maturity stage,and starch was extracted respectively to observe and compare the morphology,quantity,volume and surface area distribution characteristics of starch granules,starch pasting properties(RVA),thermodynamic properties(DSC),crystal structure and chain length distribution.The results showed that the total starch content and amylopectin content of Suluomai No.2 were significantly lower than those of Yangmai 29,and there was no significant difference in amylose content.The surface of A-type starch in Yangmai 29 had obvious‘equatorial groove’,and the agglomeration of B-type starch in Suluomai No.2 was more obvious.Besides,the number and volume of starch granules in the two materials showed a weak bimodal distribution,and the surface area showed a bimodal distribution.The endosperm starch was basically composed of C-type starch granules,and the total volume was mainly determined by A-type starch granules.The surface area of A-type starch granules accounted for more than 50%.The number,volume and surface area of C-type starch granules in Suluomai No.2 were higher than those in Yangmai 29,while the trend of A-type and B-type starch granules was opposite.Furthermore,the peak viscosity,minimum viscosity,breakdown and peak time of Suluomai No.2 were significantly higher than those of Yangmai 29,while the final viscosity and setback showed the opposite trend.The thermodynamic parameters and enthalpuy value of Yangmai 29 were higher than those of Suluomai No.2.Additionally,the starch crystal structure of the two materials was typical A-type crystal structure,and the crystallinity of Suluomai No.2 was higher than that of Yangmai 29.The chain length of amylopectin was relatively affected by the short chain.The relative ratio of the short chain of amylopectin in Yangmai 29,that was,the degree of polymerization of 6~12,was higher than that of Suluomai No.2.