Patindol James, Wang Ya-Jane
Department of Food Science, University of Arkansas, Fayetteville, AR 72704, USA.
J Agric Food Chem. 2003 Apr 23;51(9):2777-84. doi: 10.1021/jf026101t.
This work compared the molecular structures and physicochemical properties of starches obtained from chalky and translucent kernels of six rice cultivars. Starch samples were prepared according to a modified alkali steeping method. Crystallinity, pasting characteristics, and thermal properties were studied by X-ray diffraction, rapid viscosity analysis, and differential scanning calorimetry, respectively. Starch molecular size fractions (amylopectin, amylose, and intermediate material) were estimated by high-performance size exclusion chromatography, and the chain length profiles of isoamylase-debranched amylopectin were evaluated by high-performance anion-exchange chromatography with pulsed amperometric detection. Starches from chalky kernels contained less amylose (more amylopectin) and more short branch-chain amylopectin (less long branch-chain amylopectin) compared with the translucent kernel starches. Differences in starch structural features significantly correlated with observed variation in grain translucency, starch X-ray diffraction patterns, thermal properties, and pasting characteristics. Starch synthesis in chalky kernels may slightly favor glucan chain branching over chain elongation.
本研究比较了6个水稻品种垩白粒和半透明粒中淀粉的分子结构和理化性质。淀粉样品采用改良碱浸法制备。分别通过X射线衍射、快速粘度分析和差示扫描量热法研究了结晶度、糊化特性和热性质。采用高效尺寸排阻色谱法估算淀粉分子大小级分（支链淀粉、直链淀粉和中间物质），并通过高效阴离子交换色谱-脉冲安培检测法评估异淀粉酶脱支支链淀粉的链长分布。与半透明粒淀粉相比，垩白粒淀粉的直链淀粉含量较低（支链淀粉含量较高），短支链支链淀粉含量较高（长支链支链淀粉含量较低）。淀粉结构特征的差异与观察到的籽粒透明度、淀粉X射线衍射图谱、热性质和糊化特性的变化显著相关。垩白粒中的淀粉合成可能略微有利于葡聚糖链分支而非链延伸。
