生长秀节对糯玉米淀粉晶体结构和糊化特性的影响

以8个糯玉米品种为材料，利用X-射线衍射仪(X-Ray)和快速黏度分析仪(RVA)分析了淀粉在春季和秋季的晶体结构和糊化特性。结果表明，生长季节不影响淀粉的结晶类型，供试糯玉米淀粉样品的X-射线衍射图谱均表现出典型的“A”型衍射特征。然而，淀粉的晶体结构和糊化特性在生长季节间存在显著差异。和春季糯玉米淀粉相比，秋季糯玉米淀粉具有较高的结晶度、尖峰强度、峰值黏度、谷值黏度、终值黏度和崩解值。糯玉米淀粉的回复值较低，且秋季糯玉米淀粉显著低于春季糯玉米淀粉。淀粉的结晶度、尖峰强度和糊化特征值存在显著的基因型差异。相关分析表明，结晶度和各尖峰强度呈两两显著正相关。结晶度和峰值黏度、崩解值极显著正相关(相关系数分别为0.72和0.85)，和谷值黏度、糊化温度显著正相关(相关系数分别为0.52和0.55)，和回复值显著负相关(相关系数-0.49)。糯玉米淀粉糊化特性在不同生长季节中的变化主要由淀粉晶体结构(结晶度和尖峰强度)变化所致。

Crystalline Structure and Pasting Properties of Starch in Eight Waxy Corn Cultivars Grown in Spring and Autumn

X-ray diffraction technique is widely used in the study of crystal characteristics of starch granule. Waxy corn (Zea mays L.) has a higher crystallinity and better pasting properties than other kinds of corn, which is of good value in industry. The pasting properties of corn are affected by genotypes and growing conditions, and even regulated by the cultivation to some extent. Currently, there is rare knowledge on the differences of starch in waxy corn cultivars grown in different seasons. In this study, starch isolated from eight Chinese waxy corn cultivars grown in spring and autumn, were evaluated for crystalline structure and pasting properties using the X-ray Diffraction and Rapid Visco Analyzer, respectively. All starch samples showed a typical A-type diffraction pattern, indicating the growing season had no effect on it. However, the growing season significantly influenced the starch crystallinity and pasting properties. Starch from autumn-sown plant, compared with that from spring-sown plant, showed higher values in crystallinity, peak intensities (2θ = 15°, 17°, 18°, 20°, and 23°, respectively), peak viscosity, trough viscosity, final viscosity, and breakdown. The setback of starch of waxy corn was low, and that grown in autumn was significantly lower than that in spring. The crystallinity, peak intensity, and pasting characteristics were significantly different among the eight waxy corn cultivars. The crystallinity was positively correlated with the peak viscosity (r = 0.72, P < 0.01), breakdown (r = 0.85, P < 0.01), trough viscosity (r = 0.52, P < 0.05), pasting temperature (r = 0.55, P < 0.05), and negatively correlated to setback (r = -0.49, P < 0.05). The differences of pasting properties between growing seasons were mainly caused by the changed of crystallinity and peak intensity of starch in waxy corn.