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淀粉结晶结构对淀粉水解过程的影响 总被引:2,自引:0,他引:2
本文采用广角X射线衍射分析技术研究了玉米原淀粉以及超声波,电场,磁场作用后的玉米淀粉微晶的组成,性质及其变化规律,测试了玉米淀粉在不同物理场作用下基本晶体参数,研究了不同物理场对淀粉结晶结构的影响情况。 相似文献
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不同热处理方式对绿豆淀粉颗粒特性影响研究 总被引:1,自引:0,他引:1
湿热处理前后绿豆淀粉的颗粒形貌基本未发生变化。随着热处理温度的提高,淀粉的结晶结构发生一定程度的变化,表现为特征峰部分融合、峰强度下降以及结晶度降低。但处理前后的X射线图谱表明,处理后的绿豆淀粉基本保持了原有的A型结晶结构。与原淀粉相比,湿热处理后玉米淀粉的结晶结构变化幅度不大。压热处理后绿豆淀粉,其颗粒形貌已经完全发生了变化,颗粒破裂重组,不同淀粉颗粒中的链淀粉相互形成氢键,从而改变了原淀粉的结晶结构,从X射线衍射图谱我们可以看出,处理后淀粉有新结晶峰的形成。 相似文献
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淀粉老化是被破坏的淀粉分子链重新结合成有序结构的过程,其机制十分复杂,因此需要多种方法相结合才能全面、准确地分析老化过程中淀粉特性的变化。由于淀粉老化在很大程度上影响米面制品的货架期和感官品质,因此,对比分析淀粉老化检测技术无论对淀粉理论的发展,还是对米面制品的品质改良都具有重要的意义。本文对淀粉老化目前应用范围最广的技术检测方法进行阐述,分别从形变测试、光谱法、热分析法和微观结构角度总结各个技术的检测原理,深入分析不同检测方法针对样品的主要测量属性和对结晶结构的表征形式,为淀粉老化检测方法的选择提供参考。 相似文献
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为探究氢键对静电纺淀粉纤维膜的影响,以二甲基亚砜/水为溶剂体系对淀粉进行溶解制备静电纺纤维膜。通过调节二甲基亚砜/水体系中含水量,诱导水分子与淀粉分子链上的羟基结合形成氢键,研究氢键对淀粉溶解及淀粉纤维成型的影响。通过扫描电子显微镜、红外光谱、差热分析、X线衍射及拉伸实验等对静电纺淀粉纤维的表面形貌、结构和力学性能进行表征。结果表明:二甲基亚砜破坏了淀粉分子中的氢键,有利于淀粉的溶解;随着二甲基亚砜/水体系中含水量的增加,水与淀粉分子链中的羟基形成了氢键。氢键的形成会对淀粉纤维产生影响,一方面,氢键的形成使得淀粉纺丝液的可纺性变差,纤维形貌变得不均一;另一方面,对于静电纺纤维膜而言,过多的水会与淀粉分子形成氢键,抑制分子链的自由移动,导致纤维膜的断裂强度提高,断裂伸长率下降。 相似文献
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超高压处理对玉米淀粉结构及糊化特性的影响 总被引:1,自引:0,他引:1
利用光学显微、X-射线衍射、差示扫描量热、快速黏度分析技术研究了超高压处理对玉米淀粉结构及糊化性质的影响。结果显示,超高压处理能使玉米淀粉糊化,处理压力为500 MPa及600 MPa时完全糊化所需保压时间分别为15 min和5 min,但400 MPa超高压处理30 min也不会使淀粉糊化。超高压糊化过程中,淀粉颗粒结构逐渐破坏膨胀,结晶结构由A型向V型转化,RVA黏度曲线峰值黏度逐渐消失。适宜条件的超高压处理对淀粉颗粒同时具有韧化和晶体破坏作用。其中,400 MPa超高压处理5~10 min时,淀粉颗粒内部韧化作用占优,因而表现为相对结晶度、糊化温度(T_o,T_p)及糊化焓增加,而RVA曲线峰值黏度降低。 相似文献
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水分含量对小麦淀粉颗粒结晶度的影响 总被引:1,自引:0,他引:1
应用X射线衍射方法对不同水分含量的小麦淀粉颗粒的结晶度进行了研究.结果表明:随着水分含量的增加,样品的结晶度逐渐增加,并达到一个平衡值(约45%).室温下,当w(水)<11.27%时,小麦淀粉颗粒中的无定型区域处于玻璃态,衍射图形显示的是微晶区域和无定型区域两部分的衍射图形的综合;由于塑化作用的影响,增大含水量会导致更多的微晶结构的形成.当w(水)>19.4%时,淀粉颗粒中的无定型区域处于橡胶态,其X射线衍射图形仅由微晶区域形成;再增大水分含量,会导致微晶片层和剩余的无定型片层的同时分解. 相似文献
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Native potato starch granules and those complexed below the gelatinization temperature with 1-(C8 to C18)-monoglycerides were compared for solubility, swelling power (SP), viscosity, heat stability and water binding capacity (WBC). X-ray diffraction analysis proved that complexes were true clathrates (inclusion) compounds. Clathrate stability was a function of monoglyceride chain length. The presence of clathrates in granules decreased solubility by up to 90% and SP up to 10-times, while WBC dropped from 0.39 to as low as 0.25 g water/g starch. Endotherm characteristics were given for gelatinization, most perfect crystallite, and clathrate fusions. Enthalpies per mole glucose units of 15.4 kcal/mole for native starch and 27.5 for clathrate were obtained irrespective of monoglyceride chain length. 相似文献
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The effects of hydroxypropylation on phase transitions associated with gelatinization of granular rice starch were studied by differential scanning calorimetry. At a 1:1 starch/water ratio, a progressive shift of the biphasic gelatinization endotherms to lower temperatures as well as a broadening and shortening of the G endotherm with increasing molar substitution were observed, indicating increased internal plasticization and destabilization of the amorphous regions of the starch granules. The overall enthalpy of gelatinization was also reduced. Hydroxypropyl groups, which are attached to starch molecules primarily in the amorphous regions of the starch granules, behave as flexible side chains. The motion of these side chains creates a large amount of free volume, thereby lowering the glass transition and crystallite melting temperatures associated with starch gelatinization. The modified starch granules may thus be viewed as internally plasticized polymer resins which are more easily gelatinized than the unmodified starch. 相似文献
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The effects of citric acid on the properties of glycerol‐plasticized thermoplastic starch (GPTPS) were studied. In the presence of citric acid and glycerol, native cornstarch granules are transferred to a continuous phase as shown by scanning electron microscopy (SEM). As shown by thermogravimetric analysis (TGA), the improvement in thermal stability confirms that the adhesion between citric acid, glycerol, water and starch in TPS was enhanced with the addition of citric acid. It was proven by Fourier transform infrared (FTIR) spectroscopy that citric acid can form stronger hydrogen‐bond interactions with starch than glycerol. Both FTIR spectroscopy and X‐ray diffractometry of citric acid‐modified GPTPS (CATPS) revealed that citric acid can effectively inhibit starch re‐crystallization (i.e. retrogradation), because of the strong hydrogen‐bond interaction between citric acid and starch. Rheology studies revealed that citric acid can obviously decrease the shear viscosity and improve the fluidity of TPS. Citric acid can also improve the elongation of GPTPS and ameliorate the water resistance of GPTPS at high relative humidities, but decreased the tensile stress. 相似文献
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The effect of acid hydrolysis on the swelling power of pea starch granules was studied by field emission SEM (FE‐SEM). The swelling power of the native starch granules (g water absorbed/g dry starch) was 13, and this decreased to less than 2 after 1 day of acid hydrolysis. The proportion of the starch that was soluble in hot water increased from 15% for native starch to 75% after 1 day of hydrolysis. The swelling power of the starch decreased further, and solubility increased, with more extended hydrolysis. The decrease in swelling power and increase in solubility were attributed mainly to the disruption of side chains of amylopectin. Observations with FE‐SEM indicated that starch granules were still able to melt and coalesce after 1 day of acid hydrolysis, but after 2 days solubilization of starch chains occurred predominantly rather than swelling when the granules were heated in excess water. The intactness of amylopectin is proposed to play a crucial role in the swelling power of starch granules and in the structure of granule ghosts. 相似文献
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采用光学显微镜(LM)及扫描电子显微镜(SEM)观察木薯淀粉、木薯淀粉- 黄原胶复配体系在糊化过程中淀粉颗粒形态的变化。淀粉糊化是淀粉与水分相互作用的过程,利用核磁共振仪(NMR)测定质子自旋- 自旋弛豫时间(T2),来反映体系糊化过程中黄原胶对水分运动性的影响;通过测定渗漏直链淀粉含量,反映黄原胶对木薯淀粉糊化过程中链段运动性的影响,从而探究木薯淀粉在黄原胶为连续相体系中的糊化机理。结果表明:黄原胶一定程度上可抑制升温过程中淀粉颗粒的膨胀,同时SEM图显示黄原胶包裹于木薯淀粉颗粒周围,形成空间位阻使得淀粉颗粒分散均匀,与淀粉糊具有良好的相容性;升温过程中质子自旋- 自旋弛豫时间(T2)的差异体现了糊化过程中水分分布及结合程度的变化,由于黄原胶的吸水及包裹作用使得淀粉糊化温度升高,热糊稳定性提高,表现为T2 先降后升的拐点由50℃升高至60℃及95℃较高的T2;黄原胶的加入使得体系中链段运动性降低,表现为直链淀粉渗漏量随着黄原胶配比增加而减少。 相似文献