生长季节对糯玉米淀粉粒分布和热力学特性的影响

以8个糯玉米品种为材料，利用激光衍射粒度分析仪和差示扫描量热仪分析了春播和秋播糯玉米淀粉粒分布和热力学特性。结果表明，糯玉米淀粉主要由直径<13 μm的颗粒组成，占总数目的71.7%~84.3%。颗粒体积和表面积呈双峰分布，>17 μm颗粒占比例最高，9~13 μm颗粒占比例较高，<9 μm颗粒占比例最低。和春播相比，秋播处理使糯玉米粉中<17 μm颗粒体积和表面积比例升高，>17 μm颗粒体积和表面积比例降低，<9 μm的颗粒数目增多，>9 μm颗粒数目减少。淀粉热力学特征参数中，秋播处理下转变温度(起始温度、峰值温度和终值温度)、峰值指数和回生值降低，糊化范围扩大，但热焓值总体上无显著变化。结合前期研究结果，9~13 μm和13~17 μm颗粒体积比例与淀粉的结晶度、峰值黏度和崩解值显著正相关，与峰值温度和回生值显著负相关。>17 μm颗粒体积比例与结晶度、峰值黏度和崩解值极显著负相关，与峰值温度和回生值显著正相关。糯玉米淀粉粒分布在不同季节下不同，导致淀粉糊化特性和热力学特性发生变化。

Starch Granule Size Distribution and Thermal Properties of Waxy Maize Cultivars in Growing Seasons

Starch granule is the basic composition in starch and affects the starch physicochemical properties. In the study, starch isolated from eight Chinese waxy maize cultivars sown in spring and autumn was evaluated for granule size distribution and thermal properties using the laser diffraction particle size analyzer and differential scanning calorimetry, respectively. The results presented that the most number of starch granule size was less than 13 μm, with the percentage between 71.7% and 84.3%. The distribution frequency showed a typical two-peak curve in starch granule volume and surface area, the starch granule with the diameter higher than 17 μm accounted for the highest percentage, followed by that with the diameter between 9 and 13 μm, and that with the diameter lower than 9 μm was the lowest. Compared with spring sown plant, autumn sown plant presented higher volume and surface area percentage of starch granule less than 17 μm, and increased the number of starch granule less than 9 μm. Among thermal characteristics, in autumn sown treatments, transition temperature (onset-, peak-, and conclusion temperature), peak height index and percentage of retrogradation were decreased; gelatinization range was enlarged, whereas the gelatinization enthalpy was similar in two treatments in general. With the finding of previous study, the volume percentage of starch granule of 9–13 μm and 13–17 μm was positively correlated to crystallinity, peak viscosity and breakdown, and negatively correlated to peak temperature and percentage of retrogradation; that of higher than 17 μm was negatively correlated to crystallinity, peak viscosity and breakdown, and positively correlated to peak temperature and percentage of retrogradation. The change of starch granule size distribution among different growing seasons for waxy maize resulted in the change of thermal and pasting properties.