谷粒湿热处理对薏仁米淀粉形态、结构与热特性的影响

为了研究薏仁米除淀粉外的其他营养组分对水和热的屏障作用，对3 种薏仁米（大粒薏仁米（big Coix seed，BCS）、小粒薏仁米（small Coix seed，SCS）和半透明薏仁米（translucent Coix seed，TCS））进行湿热处理，分离提取得到薏仁米谷粒湿热处理（heat-moisture treatment，HMT）淀粉，运用扫描电子显微镜、普通光学显微镜、激光粒度仪、X射线衍射仪、傅里叶变换红外光谱仪、差示扫描量热仪等对HMT淀粉进行测定，比较处理前后淀粉的差异，探究HMT对淀粉形态、大小、结构、热特性的影响。结果表明，HMT使得淀粉颗粒表面破损、气孔增大、偏光十字减弱，淀粉双螺旋结构、结晶区和无定形区被破坏，淀粉与淀粉分子、蛋白质、脂类等的作用加强，淀粉分子有不同程度的重排。这些变化使得淀粉凝胶温度升高，晶体内异质性减弱，解螺旋所需能量下降，其中BCS淀粉的变化较小，直链淀粉含量高的TCS淀粉受HMT影响最大。因此，应依据HMT前后不同淀粉的变化在加工过程中进行合理的应用。

Morphology,Structure and Thermal Properties of Starch from Heat-Moisture Treated Coix Seeds

Heat moisture treatment was imposed on three kinds of Coix seeds (big Coix seed (BCS), small Coix seed (SCS) and translucent Coix seed (TCS)) to explore the water and heat barrier properties of non-starch components. For this purpose, heat moisture-treated (HMT) Coix seed starches were prepared, and scanning electron microscopy, optical microscope, laser particle analyzer, X-ray diffraction, infrared spectrometry and differential scanning calorimetry were used to explore the impact of HMT of Coix seeds on the morphology, size, structure and thermal properties of starch. The results indicated that HMT caused damage to starch granule surface, increased stomatal size, and weakened birefringence. Meanwhile, the double helix structure and the crystalline and amorphous region were broken, the interaction of starch with itself, and with protein and lipid was reinforced, and the starch molecules were reordered to different degrees. As a result, HMT increased the gelatinization temperature of the starches, weakened crystal heterogeneity, and decreased the energy required for uncoiling. BCS starch was influenced slightly, while TCS starch, rich in amylose, was affected heavily by HMT. Thus, we can apply Coix seed starch more reasonably according to variations in starch properties after HMT.