糯玉米胚乳重组淀粉的热力学和晶体特性

Thermal and Crystalline Properties of the Reconstituted Starch in Waxy Corn Endosperm

以7个糯玉米品种为材料,分离糯玉米大、小淀粉粒,以不同重量比的大、小淀粉粒配比组成重组淀粉,采用差示扫描量热仪(DSC)和X-射线衍射仪(XRD)研究重组淀粉的热力学和晶体特性。结果表明,7个糯玉米品种按大、小淀粉粒配比的重组淀粉起始温度、峰值指数、热焓值和结晶度及各个衍射峰的尖峰强度整体上表现为3:0>2:1>1:1>1:2>0:3配比;峰值温度、终值温度和糊化范围整体上表现为3:0<2:1<1:1<1:2<0:3配比。相关分析发现,7个糯玉米品种重组淀粉中大淀粉粒所占比例与起始温度(r=0.86~0.99)、热焓值(r=0.90~0.97)、峰值指数(黑糯4号除外,r=0.90~0.99)及结晶度(r=0.86~0.98)均呈(极)显著正相关;与峰值温度(西星黄糯6号除外,r=-0.88^-0.98)、终值温度(r=-0.89^-0.97)和糊化范围(r=-0.86^-0.98)呈(极)显著负相关;小淀粉粒所占比例恰好相反。重组淀粉中大淀粉粒比例越高,淀粉糊化起始温度、峰值指数、热焓值及结晶度越高;峰值温度、终值温度和糊化范围越低。

Seven varieties of waxy corn were used to isolate large and small starch granules and constitute the reconstituted starch according to different weight ratio. Thermal and crystalline properties were determined by dint of differential scanning calorimetry（DSC） and X-Ray diffraction（XRD）, respectively. The results showed that onset temperature（To）, peak height index（PH/）, gelatinization enthalpy（AHgel）, erystallinity degree and peak intensity ex- hibited 3：0 〉 2：1 〉 1：1 〉 1：2 〉 0：3, and peak temperature（Tp）, conclusion temperature（Tc） and gelatinization range（R） represented 3：0 〈 2：1 〈 1：1 〈 1：2 〈 0：3. Correlation analysis showed the percentage of large starch granule in the re- constituted starch was positively（highly） significantly correlated with To（r was equal to 0.86 to 0.99）, AHgel（r was equal to 0.90 to 0.97）, PHI（except for Heinuo 4, r was equal to 0.90 to 0.99） and crystallinity degree （r was equal to 0.86 to 0.98）, and negatively（highly） significantly correlated with Tp（except for Xixinghuangnuo 6, r was equal to -0.88 to -0.98）, Tc（r was equal to -0.89 to -0.97） and R （r was equal to -0.86 to -0.98）. The relations of the percentage of small starch granule and these properties were contrary. Therefore, the higher percentage of large starch granule in the reconstituted starch was, the higher To, PHI, Attgel and crystallinity degree were, and the lower Tp, Tc and R were.