不同品种绿豆淀粉微观结构和热力学特性的比较

Comparison of Microstructure and Thermal Properties of Starch from Nine Mung Bean Cultivars

摘要:

以9个品种绿豆的淀粉为研究对象，利用扫描电镜分析、激光粒度分析、差示扫描量热分析和x-射线衍射分析等现代仪器分析方法，研究了绿豆淀粉的颗粒形貌、结晶结构和热力学性质。SEM分析表明，绿豆淀粉颗粒形状有肾形、椭圆形、凸圆形和小球形等，其颗粒形态在不同品种间没有明显差别。激光粒度分析表明，绿豆淀粉粒径大小在不同品种间有明显差异，其粒径范围为18.46~26.81 μm，粒径总平均值为20.71 μm。不同品种绿豆淀粉均具有典型的C-型衍射图谱，但其相对结晶度在不同品种间存在明显差别，相对结晶度范围为16.23%~42.39%。DSC测定结果表明，绿豆淀粉的胶凝温度（To、Tp和Tc）和热焓值（?H）在不同品种间存在较大差异，且部分品种间差异显著（p<0.05）；To、Tp、Tc和?H范围分别为：51.02-63.03 ℃，64.81~73.04 ℃，70.04~79.44 ℃和1.09~1.97 J/g。

Abstract:

Starch was extracted from nine different mung bean cultivars and their morphological characteristics, crystal structure, and thermal properties were studied by scanning electron microscopy (SEM), laser particle-size analysis, differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). SEM results showed that the mung bean starch particles were kidney-shaped, elliptical, dome-shaped, and small spherical, with no significant morphological differences between different cultivars. Laser particle-size analysis indicated significant differences in the size of starch granules between different cultivars, varying from 18.46 to 26.81 μm, with an average of 20.71 μm. Starch extracted from all nine cultivars had a typical C-type X-ray diffraction pattern, but their relative crystallinity was significantly different, lying between 16.23% and 42.39%. DSC analysis demonstrated that gelation temperatures (To, Tp, and Tc) and enthalpy (?H) varied greatly, ranging from 51.02 ℃ to 63.03 ℃, 64.81 ℃ to 73.04 ℃, 70.04 ℃ to 79.44 ℃, and 1.09 to 1.97 J/g, respectively, where the differences were statistically significant (p < 0.05) among some cultivars.