淀粉颗粒微观结构及结晶调控技术的研究进展

淀粉颗粒的微观结构与结晶形态不仅与食品质地、加工特性和消化特性息息相关,还赋予淀粉颗粒极强的可塑造性。淀粉广泛应用于食品、化学工业和医疗等领域,已成为重要的功能性材料。本文综述了近年来淀粉颗粒微观结构的研究进展,概述了其不同晶体与颗粒结构之间的关系,并探讨了晶体之间的相互转化以及不同改性条件对淀粉结构特性的影响。

薯蓣属淀粉的研究进展

薯蓣是重要的药食两用植物,而淀粉是其根茎中最丰富的碳水化合物。综述了近年来薯蓣淀粉的研究进展,介绍了薯蓣淀粉的颗粒结构,概述了薯蓣淀粉尤其是薯蓣抗性淀粉的应用,并探讨了不同的物理和化学改性方法对薯蓣淀粉结构及应用带来的影响。

淀粉有哪些性状特性

淀粉是粉丝生产的原料。在自然界中分布很广，它是高等植物中常见的组成部分，也是碳水化合物贮藏的主要形式。在大多数高等植物的所有器官中都含有淀粉，这些器官包括叶、茎（或木质组织）、根（或块茎）、球茎（根、种子）、果实和花粉等。除高等植物外，在某些原生动物、藻类以及细菌中也都可以找到淀粉粒，不同的淀粉具有不同的性状，而淀粉的性质不同又决定了淀粉的用途不同。

Changes of Granule Structure and Enzyme Hydrolysability of Starch in Upper Flue-cured Tobacco Leaves During Bulk Flue-curing

[Objective] This study aimed to investigate the changes of granule struc- ture, characteristic and related enzymatic activity of starch in upper flue-cured tobac- co leaves during bulk flue-curing process, to provide theoretical basis for reasonably regulating the starch content in upper flue-cured tobacco leaves and improving the quality of upper flue-cured tobacco leaves. [Method] Changes of amylase activity, enzyme hydrolysability and granule structure of starch in upper flue-cured tobacco leaves were studied during flue-curing process using conventional physical and chemical analysis and SEM. [Result] During the flue-curing process, the starch con- tent of tobacco leaves changed greatly at yellowing stage, and the activity of amy- lase presented the double-peak curve. The SEM observation results showed that most of the starch granules in fresh tobacco leaves were spheroidal and long cylin- drical, while some individuals were in irregular shape, with obvious groove-like in- vagination and layered structure on granule surface; during the flue-curing process, a large amount of starch granules showed layered structure on the surface at yellow- ing stage, and the long cylindrical starch granules were reduced greatly; at the end of flue-curing, there were barely any long cylindrical starch granule in flue-cured to- bacco leaves. Average long-axis-diameter of starch granules in fresh tobacco leaves was 3.21 μm, showing an overall gradually increasing trend during the flue-curing process, which was significantly enhanced at 38 and 42 ℃. The diameter of starch granules increased by more than 60% at the end of 42 ℃ and there was no re- markable difference after 47 ℃. During the flue-curing process, enzyme hydrolysabil- ity of starch in flue-cured tobacco leaves first increased, reached a peak at 38 ~C, and then decreased. [Conclusion] During the bulk flue-curing, the yellowing stage is the critical period for starch content, granule structure and characteristic changes of flue-cured tobacco leaves, it is of positive effects to improve the quality of upper flue-cured tobacco leaves by regulating the flue-curing conditions at yellowing stage.

THE STRUCTURE OF THERMOPLASTIC STARCH

The granular structure, crystal structure and gelatinization temp. of thermoplastic starch were studied with a polarized light microscope and a scanning electron microscope, and the crystallinity and crystalline patterns were determined through X ray diffraction. The results indicate that the original granular structure and spherical crystalline structure of starch were disrupted by the action of pressure, heat and shear force with the help of additives. The starch can be melted during extrusion, and part of the spheric crystal was destroyed and changed into a continual amorphous with a few crystalline fractions dispersed in it. The configuration of starch molecules changed from double helices to single helix, which indicated the formation of the complex.

水稻双粒基因tg1对稻米品质的影响

为探究双粒基因tg1对稻米品质的影响,本研究以‘浙粳22’的双粒突变体‘浙粳22-tg1’为供体,将tg1基因导入大粒品种‘SLG’,比较了‘浙粳22’、‘浙粳22-tg1’、‘SLG’和‘SLG-tg1’在灌浆速率、稻米品质指标和淀粉颗粒形态上的不同,分析双粒基因tg1对稻米品质的影响,发现新品系‘SLG-tg1’灌浆速率高,在稻米品质包括外观品质、加工品质以及蒸煮食味和营养品质上都有显著改善。淀粉颗粒的电镜扫描观察表明,与‘SLG’相比,‘SLG-tg1’淀粉颗粒结构更加紧密,为优质米类型的多面体形。因此,本研究发现转育tg1基因可改善稻米品质,为选育优质水稻新品种提供参考。