马铃薯交联淀粉的制备与结构表征

以三偏磷酸钠为交联剂,水分散法制备了马铃薯交联淀粉,应用红外光谱、X射线衍射、扫描电镜和偏光显微镜等分析测试方法,观察和研究了不同取代度马铃薯交联淀粉的颗粒形貌及其结晶结构。结果表明,产物取代度随交联反应时间的延长而增大;交联反应主要发生在淀粉分子的无定形区,在结晶区也有一定程度的反应;随着取代度的增大,淀粉中受侵蚀的颗粒增多,颗粒表面的小凹痕数量明显增加,部分颗粒表面变粗糙,颗粒内部出现凹陷甚至爆裂;交联淀粉的偏光十字清晰易见;1 017.08cm-1的吸收峰强度加强,证实在淀粉中引入了磷酸根基团。     

羟丙基淀粉颗粒形貌和结晶结构的研究

本文应用扫描电镜、X-光衍射和偏光显微等现代分析技术，观察和研究了不同取代度羟丙基淀粉和原淀粉的颗粒形貌及其结晶结构。结果表明：淀粉羟丙基化反应首先发生在淀粉颗粒中结构较薄弱的非结晶区。随着取代度增大，淀粉颗粒表面发生凹凸不平变化，出现洞穴和裂痕，使淀粉易于糊化，糊化温度降低。     

超声波作用对木薯淀粉化学反应性能的影响

淀粉颗粒内部具有结晶区和非结晶区,淀粉的变性化学反应主要发生在非结晶区。实验表明,超声波作用的木薯淀粉颗粒基本保持着原木薯淀粉的颗粒形状,而木薯淀粉颗粒的偏光十字特征减弱或消失;超声波作用没有破坏木薯淀粉分子的原有的结构,没有新的化合物产生,经超声波作用后的木薯淀粉的红外结晶指数下降,木薯淀粉颗粒表面不再圆滑平整,说明超声作用破坏了木薯淀粉颗粒表层结晶结构。超声波作用后的木薯淀粉与原木薯淀粉分别合成羟丙基淀粉,羟丙基淀粉的取代度分别为0.1895与0.0725,说明经超声波作用后的木薯淀粉的反应性能增强,因为超声波作用后的木薯淀粉颗粒结晶结构被破坏,反应试剂更容易进入淀粉颗粒内部进行反应,反应性能得到了提高。     

三氯氧磷交联淀粉生物降解过程中形貌和结晶结构的变化

利用扫描电子显微技术和多功能偏光显微技术系统研究三氯氧磷交联淀粉在生物降解过程中的颗粒形貌和结晶结构变化情况.结果表明：随着交联度的增大,颗粒被微生物破坏的程度变小.经三氯氧磷高交联后的木薯淀粉在微生物降解过程中颗粒的偏光十字变化不明显,表明一定程度的三氯氧磷交联会抑制微生物对淀粉颗粒的作用.     

酯化交联淀粉反应及性质的研究

由三氯氧磷变性木薯淀粉所得的酯化交联淀粉,颗粒完整,形貌和偏光十字形态保持不变,反应主要发生在淀粉颗粒的无定形区内;经红外光谱等检测,发现产物分子中存在P—O—C和P＝O基团,表明淀粉分子中的羟基置换出三氯氧磷分子中的氯原子而发生酯化和交联;极小取代度的变性淀粉,其碘复合物的可见光吸收光谱与原淀粉相似,三氯氧磷最先和支淀粉作用.     

高交联木薯淀粉非晶化特性研究

研究了以三氯氧磷为交联剂的高交联木薯淀粉的制备方法,报告了高交联木薯淀粉颗粒随反应取代度增加而逐渐非晶化的现象;同时,采用偏光显微镜和广角Ｘ－射线衍射对其由多晶态向非晶态的渐变过程进行了研究,提出高交联木薯淀粉存在着不同于原淀粉多晶颗粒态的只含无定形结构的非晶颗粒态。对非晶颗粒态高交联木薯淀粉颗粒的粒度分布的进一步研究结果还表明,此时的淀粉颗粒发生了轻度有限的膨胀     

交联-羧甲基复合变性淀粉合成及结构表征

以环氧氯丙烷为交联剂,一氯乙酸为醚化剂,合成交联-羧甲基复合变性淀粉,考察交联、羧甲基化对淀粉表观及内部结构的作用.通过可见光吸收光谱,差示扫描量热、扫描电镜、X衍射、红外光谱对原淀粉、交联淀粉、羧甲基淀粉、复合变性淀粉进行结构与性质的表征及分析.结果显示:交联反应主要发生在淀粉颗粒表面的无定形区,羧甲基化反应发生在淀粉颗粒的无定形区及结晶区,交联-羧甲基复合变性淀粉兼有单一变性淀粉的性能.     

乌冬面专用变性淀粉及其结构表征

采用交联―酯化―预糊化复合变性制备乌冬面专用改性淀粉,并与木薯原淀粉、交联淀粉及交联―酯化淀粉进行比较。结果表明,交联淀粉偏光显微及颗粒形貌没发生明显变化,交联变性并未破坏淀粉结晶结构;交联―酯化淀粉颗粒出现粘连和聚集现象,部分颗粒表面出现凹陷和裂纹现象;红外光谱表明,交联―酯化―预糊化复合变性淀粉在1 728 cm–1、1 247 cm–1附近出现新的吸收峰,分子内引入乙酰基团,X–射线衍射光谱显示,交联―酯化―预糊化复合变性淀粉在5.6°和22°处衍射峰强度减弱,A型特征峰加强,结晶类型由"C"型向"A"型转变;交联―酯化淀粉经预糊化处理后,淀粉颗粒膨胀破裂,结晶结构受到彻底破坏,淀粉偏光十字消失,但预糊化处理未破坏淀粉分子化学键。     

醚化、交联对玉米淀粉功能性质的影响

本文研究了醚化和交联反应对玉米淀粉物理性质和结构的影响。实验结果表明:醚化明显地改善了淀粉糊的透明度和低温稳定性,降低了糊化温度;醚化淀粉再经交联后,可改善淀粉糊的粘度稳定性。醚化及交联反应主要在淀粉的非结晶区进行,反应并未破坏淀粉颗粒。醚化影响直链淀粉的构象并在颗粒表面形成空穴,交联则使淀粉颗粒在蒸煮后仍保持完整并抑制了直链淀粉的渗出。     

高交联玉米淀粉的非晶化特性

研究了以三氯氧磷为交联剂的高交联玉米淀粉的制备方法,报道了高交联玉米淀粉颗粒随反应取代度增加而逐渐非晶化的现象.采用偏光显微镜和广角X-射线衍射对其由多晶态向非晶态的渐变过程进行了研究,提出高交联玉米淀粉中存在不同于原淀粉多晶颗粒态的只含无定形结构的非晶颗粒态。对非晶颗粒态高交联玉米淀粉颗粒的粒度分布的进一步研究结果还表明,此时的淀粉颗粒发生了轻度的膨胀。     

Preparation of highly substituted carboxymethyl starch using a twin‐screw extruder

Carboxymethyl starch was prepared by reacting corn starch with sodium mono chloro acetate (SMCA) in a Brabender TSE‐20 co‐rotating twin screw extruder. The effects of the SMCA/starch ratio (theoretical degrees of substitutions 2.73, 3.62, and 4.53), aqueous ethanol/(starch + SMCA) ratio (0.13 and 0.25) and the screw configuration (0, 1, and 2 kneading blocks) on the degree of substitution (DS) and reaction efficiency were studied. A 3 × 2 factorial design with 3 levels of the starch/SMCA ratio and 2 levels of the aqueous ethanol/(starch + SMCA) ratio were used. This 3 × 2 factorial design was blocked, with the screw configuration as the blocking variable. The effects of the SMCA/starch ratio and the screw configuration were found to be significant. The carboxymethylated starches were characterized using FTIR, SEM, and XRD. The microstructure of the carboxymethylated starches, studied using SEM, revealed that the integrity of the starch granules was partially preserved at low aqueous ethanol levels when no kneading block was used. However, for all other reaction conditions either granule agglomeration or fusion was observed. XRD analysis indicated substantial loss of crystallinity in the carboxymethylated starches, irrespective of the damage to the granule structure. The highest DS and the highest reaction efficiency obtained were 1.54 and 0.42, respectively.     

西米交联淀粉的理化性质

以三偏磷酸钠为交联剂,采用水分散法制备西米交联淀粉,利用扫描电镜、聚焦光束发射测量仪、Bra-bender快速黏度计和紫外分光光度计对其性质进行测定和分析,并与西米原淀粉进行比较。结果表明:西米交联淀粉发生了中等程度的交联;西米交联淀粉保持了西米原淀粉绝大多数颗粒完整、呈椭圆形、存在断切面和断切面处有凹坑的形貌特征,但其表面比较粗糙,有凹痕,且断切面处凹坑更加明显;西米交联淀粉颗粒粒径分布图呈单峰,在水相中的平均粒径为30.1μm,比西米原淀粉颗粒小;西米交联淀粉比西米原淀粉难于糊化,其热稳定性和冷糊稳定性均优于西米原淀粉,有很高的最终黏度;西米交联淀粉的透光率为5.1%,小于西米原淀粉,其透明度较差。     

木薯羧甲基淀粉的机械活化固相化学法制备、表征及其特性

以木薯淀粉为原料,氯乙酸钠为醚化剂,氢氧化钠为催化剂,采用机械活化固相化学反应法制备羧甲基淀粉。以取代度为评价指标,通过单因素和正交试验设计优化确定最佳制备工艺,采用傅里叶红外光谱（Fourier transform infrared spectroscopy,FTIR）、X-射线衍射（x-ray diffraction,XRD）、扫描电镜（scanning electron microscope,SEM）对羧甲基淀粉的结构进行表征,并考察羧甲基淀粉的理化特性。结果表明,最佳工艺参数为淀粉与氯乙酸钠物质的量比1∶1、反应温度50?℃、反应时间1.5?h、氢氧化钠溶液质量分数18.8%、搅拌速率380?r/min、球磨介质堆体积500?mL,在此条件下制备的羧甲基淀粉取代度为0.540?1。FTIR、XRD、SEM检测进一步证实木薯淀粉发生了羧甲基化反应。理化特性结果显示,羧甲基淀粉的黏度升高,溶解度增大,吸水性、保水性、冻融稳定性、抗酸碱性、抗酶解性等均得到较好的提高。     

Synthesis of high fatty acid starch esters with 1‐butyl‐3‐methylimidazolium chloride as a reaction medium

In this work, high fatty acid esters of corn starch were synthesized by reacting the starch with fatty acid methyl ester using 1‐butyl‐3‐methylimidazolium chloride (BMIMCl) ionic liquid (IL) as reaction media. The effect of reaction variables such as the catalyst amount, molar ratio of fatty acid methyl ester/anhydroglucose unit (AGU) in starch, pyridine/AGU molar ratio, reaction temperature, as well as reaction time on the degree of substitution (DS) of starch esters was investigated. The experimental results showed that the DS value of the obtained starch esters could be varied depending on the process conditions. In the optimum reaction condition, the achieved maximum DS of starch laurate and starch stearate was 0.37 and 0.28, respectively, at a reaction temperature of 110°C for starch laurate and 120°C for starch stearate for a reaction duration of 2 h. Furthermore, the starch esters were characterized by FTIR, SEM, and X‐ray diffractometry (XRD) techniques, respectively. Results from FT‐IR spectroscopy suggested that the hydroxyl groups in the starch molecules were converted into ester groups. SEM and XRD studies showed that the morphology and crystallinity of starch esters were disrupted largely in the IL medium under the reaction conditions.     

羟丁基化水平对玉米淀粉理化性质的影响

以玉米淀粉为原料,1,2-环氧丁烷为醚化剂,氢氧化钠为催化剂,乙醇为分散剂,制备出不同取代度的羟丁基淀粉。采用傅里叶变换红外仪、X射线衍衍射仪和扫描电镜等对不同取代度的羟丁基淀粉的微观结构进行表征。红外分析表明羟丁基淀粉在1371cm-1出现羟丁基的吸收峰,证明已经接上了羟丁基基团。X射线衍射分析羟丁基淀粉仍属于A型衍射图,证实了该反应主要发生在无定形区。通过扫描电子显微镜分析变性前后的表面形貌变化,表明该反应发生在淀粉颗粒表面。布拉班德粘度仪测试结果表明,淀粉糊化温度降低,回复值降低,糊峰值黏度升高,且随着取代度的提高,变化越明显,当取代度达到一定程度时,羟丁基淀粉冷水可溶。随着羟丁基取代度的增大,淀粉糊的透明度及冻融稳定性都有显著的提高。     

Homogeneous synthesis and characterization of starch acetates in ionic liquid without catalysts

Homogeneous modification of corn starch with acetic anhydride was performed in ionic liquids 1‐butyl‐3‐methylimidazolium chloride (BMIMCl) without catalysts. The results indicated that the pretreatment of starch, which starch was dissolved in BMIMCl at 105°C for 2 h before reaction, provided feasible reaction environment for starch functionalization. Optimum modification conditions for maximum degree of substitute (DS 2.11) were shown as following: acetic anhydride/anhydroglucose units (AGU) molar ratio 5:1, reaction temperature 105°C and reaction time 2 h. The pretence of acetyl groups in starch products was confirmed by FTIR and ¹H NMR spectroscopy. SEM and XRD data showed that the crystalline structure of native starch was disrupted and new structure was formed during the dissolution and modification processes. The higher DS due to acetylation had a beneficial effect on the thermal stability of samples.     

Effect of high‐pressure microfluidization on the structure of cassava starch granule

Microfluidization has been applied to modify starch granules. The study was conducted to investigate the effect of microfluidization on the structure and thermal properties of cassava starch–water suspension (20% w/w). The means of optical microscopy, SEM, FTIR spectroscopy, XRD, and DSC were applied to analyze the changes in microstructure, crystallinity, and thermal property. Microscopy observations revealed that native starch granules were oval, round, and truncated in shape. After the microfluidization treatment, a bigger starch granule was partially gelatinized, and a gel‐like structure was formed on a granular surface. No significant difference in XRD patterns of the samples were observed and all samples exhibited A‐type allomorph. Crystallinity decreased with the pressure. Sample treated at 150 MPa contains 17.1% crystalline glucan polymer, lower than that of native granules which have crystallinity of about 25.8%. A lower crystallinity means poor order of crystalline glucan polymer structure in starch granules. The disruption of crystalline order within the granule was also observed by FTIR measurement. Thermal analysis using DSC indicated that the microfluidization treatment brought about a significant decrease of melting enthalpy. The gelatinization enthalpy was 12.0 and 3.0 J/g for the native sample and samples treated under the 150 MPa, respectively. The results indicate that high‐pressure microfluidization process induced the gelatinization of cassava starch, which is evaluated by a percentage of the degree of gelatinization, due to a pronounced decrease with increasing microfluidizing pressure.     

酶促合成肉豆蔻酸淀粉酯的性质及结构表征

为提高淀粉的反应活性,采用氢氧化钠尿素法对马铃薯原淀粉进行处理,以处理后的马铃薯淀粉和肉豆蔻酸为原料,Novozyme 435为催化剂,在无溶剂体系中制备了取代度为0.018~0.065的肉豆蔻酸淀粉酯,并对其部分理化性质进行研究。结果表明:与原淀粉相比,预处理淀粉溶解度和透明度显著增加(P0.05),其膨胀度、冻融稳定性、乳化性和乳化稳定性均显著降低(P0.05)。同时,肉豆蔻酸淀粉酯的性质与其取代度密切相关,与原淀粉相比,随着取代度的增加,酯化淀粉冻融稳定性、乳化性和乳化稳定性随之升高,而其溶解度、膨胀度和透明度随之下降。扫描电子显微镜(SEM)、傅里叶红外光谱分析(FTIR)、疏水性测定对预处理淀粉及不同取代度的肉豆蔻酸淀粉酯进行观察、测定、分析,结果表明,淀粉颗粒结构被破坏,酯化淀粉具有较好的疏水性,FTIR验证了预处理淀粉及酯化淀粉的生成。