灌浆期糯米淀粉精细结构变化

Structural Properties of the Starches Isolated from Developing Waxy Rice Seeds

DOI：10.3969/j.issn.1673-1689.2018.10.008

中文关键词: 糯米淀粉 灌浆期 淀粉结构

英文关键词: waxy rice starches,pollination stage,starch structure

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中文摘要:

分别对灌浆期11、13、15、17、22、27和35 d糯稻米取样，研究其淀粉形态、晶体和分子结构，揭示糯稻米成熟过程中淀粉精细结构的变化规律，以期为筛选慢消化性、抗老化性等新型糯米淀粉食品的加工原料提供科学依据。扫描电镜（SEM）和激光粒度仪（LPSA）研究结果表明，灌浆期糯米淀粉中出现球形颗粒，随着淀粉成熟，逐渐转化成为多面体状的颗粒，且颗粒峰值粒径不断增大，由5.92 μm增加至6.77 μm。X-射线衍射图谱（XRD）研究显示，灌浆期糯米淀粉晶型不变，然而淀粉晶体结晶度从31.0%增加至37.5%。采用阴离子色谱（HPLC-AEC）、高效尺寸排阻色谱联合多角度激光检测器与示差检测器联用系统（HPSEC-RID-MALLS）对样品分子结构进行检测发现，灌浆期淀粉分支密度逐渐增加，由81.91%提高至83.88%；灌浆后期大分子淀粉分子含量增加，相对分子质量6.817×107~1.033×108；灌浆后期糯米淀粉在水中更容易聚集。

英文摘要:

In this study，waxy rice starches（WRS） were isolated from the developing waxy rice seeds that were harvested at pollination stage for 11，13，15，17，22，27，and 35 days. The structural properties，including the shape，the crystallites，and molecular structure，were studied to find the change law of starch structure during pollination stage. The results，obtained from scanning electron microscope（SEM） and laser particle size analyzer（LPSA），showed that the spherically immature starch particles gradually disappeared and powder particle size of the peak increased from 5.92 μm to 6.77 μm. The XRD data indicated that the relative crystallinity increased from 31.0% to 37.5% during pollination stage. Molecular structure analysis suggested that the weight-average molecular weight（Mw） and the number-average molar mass（Mn） were the higher for the increased side chain during later pollination stage. WRS isolated from later pollination stage was easier to gather together after gelatinization.

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