交联-羧甲基淀粉合成工艺可视化优化的研究

采用环氧氯丙烷对淀粉进行轻度交联,再对其进行醚化,制备出具有低黏度、高稳定性和透明度好的交联-羧甲基淀粉.采用可视化优化方法对交联-羧甲基淀粉合成工艺进行分析处理,预测出优化的工艺条件:环氧氯丙烷用量为0.150 g,氢氧化钠用量为12.654 g,氯乙酸用量为9.818 g,反应温度为54.2 ℃,在此条件下制得的产品取代度和沉降积分别为0.647 3和4.1 mL,与预测值0.643 9和3.878 3 mL接近.证明可视化优化方法优化效果明显,准确可靠.     

交联甘薯羧甲基淀粉的制备及影响因素的研究

以甘薯淀粉为原料,用乙醇作溶剂,用环氧氯丙烷作交联剂,氯乙酸作羧甲基化试剂,合成交联-羧甲基复合变性淀粉.研究了氢氧化钠、氧乙酸、反应温度、反应时间、乙醇用量等因素对反应的影响.以取代度为目标,用正交实验法确定了交联-羧甲基复合变性甘薯淀粉合成工艺的最佳条件为:反应温度50℃,反应时间4h,配料比m(淀粉):m(氯乙酸):m(氢氧化钠):1:0.48:0.52,在该优化条件下,交联甘薯羧甲基淀粉取代度(DS)达0.75.     

红薯淀粉羧甲基化改性研究

以红薯淀粉为原料 ,用乙醇溶剂法制备羧甲基淀粉 ,通过正交实验探讨了影响羧甲基淀粉取代度的各种因素 ,获得制备条件为 :红薯淀粉用量 10 g、氢氧化钠 7g、氯乙酸 6g、乙醇浓度 75 %、乙醇体积 75mL、碱化温度 35℃、醚化温度 4 5℃、碱化时间 4 5min、醚化时间 80min。在该优化条件下 ,红薯羧甲基淀粉取代度(DS)达 0 .87,粘度达 0 .5 1Pa·S。     

高取代度羧甲基小麦淀粉制备工艺的优化及表征

摘 要：以小麦淀粉为原料,以氯乙酸作为醚化剂,采用两次加碱法制备了高取代度的羧甲基小麦淀粉。以4.05g淀粉为基准,采用正交实验对反应条件进行了优化,得到的最佳工艺条件为：水用量6mL,无水乙醇用量60mL,氯乙酸与淀粉摩尔比1.4,氢氧化钠与氯乙酸摩尔比1.8,碱化用氢氧化钠百分比70%,碱化温度35～40℃,碱化时间0.5～1h,醚化温度50～55℃,醚化时间2～3h,在此条件下制得了取代度高达1.21的羧甲基小麦淀粉。     

羟乙基籼米淀粉的制备及结构特征

使用籼米淀粉作为原材料,采用溶媒法结合超声波处理原淀粉以氯乙醇作为醚化剂制备羟乙基籼米淀粉。通过单因素实验优化合成条件,并用FTIR、XRD、SEM和TG-DSC对产品进行结构特征分析。结果表明,在籼米淀粉10.0 g,蒸馏水30 mL时,优化合成的条件如下:温度50℃,氢氧化钠2.4 g,无水乙醇50mL,氯乙醇4 g,反应时间8 h。X射线衍射和扫描电镜分析表明籼米淀粉的醚化反应主要发生在非结晶区,醚化作用没有改变淀粉结晶区的晶型;籼米淀粉经过超声波处理和醚化后,其晶型结构与颗粒形貌均受到破坏。对比原淀粉和羟乙基籼米淀粉的红外光谱说明籼米淀粉确实发生了羟乙基化。热稳定性分析证明籼米淀粉经过羟乙基化后,其水分蒸发温度和融熔温度均降低。超声波处理有助于羟乙基淀粉的合成及破坏原淀粉的晶型结构。     

羧甲基黄姜淀粉的制备

以黄姜淀粉为原料,乙醇为溶剂,用溶剂法制备羧甲基淀粉.应用正交设计法研究了影响淀粉羧甲基化反应的各种因素,通过检测取代度确定了制取羧甲基淀粉的最佳反应条件:淀粉、氢氧化钠、氯乙酸的比值为1:2.1:1.4,乙醇浓度为0.85,醚化时间为2.5h,醚化温度为44℃.通过实验获得取代度为0.4311的羧甲基淀粉产品.     

交联羧甲基复合变性木薯淀粉的制备及性质

本实验以木薯淀粉为原料,用环氧氯丙烷作交联剂,氯乙酸作羧甲基化试剂,合成了交联-羧甲基复合变性淀粉.采用铜盐沉淀法测其取代度,筛选出了交联-羧甲基复合变性淀粉合成工艺的最佳条件为:反应温度55"C,反应时间4h,配料质量比淀粉:氯乙酸:氢氧化钠=1.00:0.44:0.44;在此条件下台成的产品取代度(DC)为0.79.与原木薯淀粉相比,交联.羧甲基反应后产物黏度增大,膨胀凝固性、热稳定性、透明度得到改善,具有较强的环境适应性和良好的应用性能.红外光谱分析发现,在1008～1164cm-1的吸收峰强度加强,证实在淀粉中引入了羧甲基.DSC分析表明,交联.羧甲基淀粉有较高的糊化温度,且更易糊化.     

高取代度羧甲基玉米淀粉制备工艺的研究

以玉米淀粉为原料,乙醇为溶剂,氯乙酸为醚化剂,研究高取代度羧甲基淀粉的制备工艺。还比较了不同淀粉、醚化剂的种类以及Na OH状态对取代度的影响。结果表明,最佳工艺为:二次加碱法,95%(质量分数)的乙醇作溶剂,淀粉乳浓度为25%,氯乙酸用量为115 g,Na OH用量为2.25(摩尔比,碱∶酸),碱化温度为40℃,碱化时间为10 h,碱化Na OH用量为1(摩尔比,碱∶酸),醚化温度为40℃,醚化时间为10 h,醚化阶段用14 g Na_2CO_3代替部分Na OH。一步法制备了取代度(DS)=1.21,反应效率(RE)=61.38%的羧甲基淀粉(CMS),非晶颗粒态淀粉的取代度比原淀粉略高,四种淀粉制备CMS取代度从高到低依次为马铃薯淀粉、木薯淀粉、蜡质玉米淀粉、玉米淀粉,氯乙酸作醚化剂时取代度远高于氯乙酸钠,固体碱制备CMS的取代度比液体碱高。     

糯玉米交联羧甲基淀粉的制备

以糯玉米淀粉为原料，采用乙醇溶剂法，在碱性条件下，合成了交联羧甲基复合变性淀粉，并对制备条件进行探索。研究表明，最佳工艺条件为n（淀粉）：n（氯乙酸）：n（氢氧化钠）=0．3：0．2：0．9，按此条件可制备出取代度0．86的糯玉米交联-羧甲基（CCMS）复合变性淀粉。     

非晶颗粒态玉米淀粉制备羧甲基淀粉

以非晶颗粒态玉米淀粉、氯乙酸为主要原料,用乙醇溶剂法制备羧甲基淀粉。研究了反应温度、时间、氯乙酸、淀粉乳浓度、水分含量对样品取代度(DS)的影响。结果表明:在淀粉乳浓度20%,n(氯乙酸):n(淀粉) =1:4,n(NaOH):n(淀粉)=1:2,乙醇溶剂含水30%条件下,55℃反应4h得到较高取代度的羧甲基淀粉。     

Moisture Accessibility of Hydrophilic Sites in Starch and Modified Starch

Pulsed NMR technique was used to determine total water, bound/mobile fraction and their force of binding in starch and hydroxyethyl starch. The accessibility of moisture to the hydrophilic sites was evaluated. Substitution of hydrophilic, bulky, hydroxyethyl group to starch increased the bound water. The force of binding increased with the increase of molar substitution of hydroxyethyl groups. The accessibility of starch to moisture is increased by substitution of hydroxyethyl groups.     

Some Studies on Modified Starch for Low Humidity Application

Starch was chemically modified by substitution with hydroxyethyl groups to three levels (0.05, 0.1, 0.15 molar substitution) to reduce the brittleness of starch film for low humidity application. Substitution with hydroxyethyl groups reduced the density and sonic modulus and increased the moisture regain of the film. The brittleness of hydroxyethyl starch film at low humidity is reduced as the flexural rigidity, intermolecular friction, tensile modulus and breaking strength is decreased and breaking extension is increased.     

A Novel Method for the Preparation of Hydroxyethyl Starch for the Cryoprotection of Human Red Blood Cells

A novel method for the preparation of hydroxyethyl starch for the cryoprotection of human red blood cells presented. By retaining the granular structure of the starch throughout a series of heterogeneous reactions, hydroxyethyl starch can be produced which contains low levels of salts and other impurities, and which is highly effective as a cryoprotective agent. It is suggested that hydroxyethyl starch with a very versatile range of properties may be prepared by simple modification of the basic procedures.     

A Study of Hydroxyethyl Starch. Part III. Comparison of Metabolic Fates between 2-0-Hydroxyethyl Starch and 6-0-Hydroxyethyl Starch in Rabbits

The blood concentration, renal excretion, and molecular-size distribution of 6-O-hydroxyethyl starch (6-O-HES) and 2-O-hydroxyethyl starch (2-O-HES), which were infused into rabbits, were compared. As a result, 6-O-HES showed a more rapid elimination from the body than 2-O-HES did, thus indicating that 6-O-HES was subjected to the same metabolic changes as 2-O-HES was, which had a lower molar substitution of hydroxyethyl groups by 0.2 to 0.3. This result might be attributed to the substitution-site effect of hydroxyethyl groups on the enzymic degradation of hydroxyethyl starch by α-amylase.     

Kinetics of the Hydroxyethylation of Starch in Aqueous Slurries

Kinetic results are presented for the hydroxyethylation of potato starch with ethylene oxide. The reactions were carried out at 303.0 K in alkaline aqueous starch slurries containing sodium sulphate as swelling inhibitor. A new side reaction was discovered: the formation of hydroxyethyl hydrogen sulphate from ethylene oxide and sulphate dianions. Part of the ethylene oxide is hydrolysed to ethylene glycol. Selectivities were determined by analysis of the products hydroxyethyl starch and ethylene glycol. Since hydroxide ions are formed in the production of hydroxyethyl hydrogen sulphate, the rate of formation of this compound could be measured by the amount of acid added to keep the pH constant. The hydrolysis of ethylene oxide towards ethylene glycol can be described by two parallel reactions: (a) by water, and (b) catalyzed by hydroxide ions. The reaction of ethylene oxide with starch is more enhanced by alkali than the base catalyzed reaction of ethylene oxide with water to ethylene glycol, causing the selectivity of the hydroxyethylation to increase from 7 to 68% if the sodium hydroxide dose is increased from zero to 0.060 mole per mole of anhydroglucose units.     

Viscosity and Gelatinization Characteristics of Hydroxyethyl Starch

Viscosity and gelatinization characteristics of corn and potato starches as well as their hydroxyethyl derivatives were investigated. The inherent viscosity increased from 164 in native corn starch to 209 in etherified one of DS 0.18. The etherified corn starch gelatinized at lower temperature than native corn starch due to their increase of DS. Maximum viscosity decreased from 93°C to 69°C for the modified corn starch. The retrogradation of starch was minimized by etherification as retrogradation ability of corn starch from its solution decrease from 22% to 6%. This is of great importance when starch is used as blood plasma volume expander. Variable results were obtained with etherified potato starch which might be due to its high contents of phosphorus.     

Evaluation of Properties of Starch and Modified Starch for Sizing and Desizing

Viscosity, gelatinization characteristics, storage stability, gelling tendency and thermal reversibility of cooked starch and modified starch paste were studied Solution rate of starch and modified starch films in water, hydrochloric acid and enzyme was evaluated. Hydroxyethyl starch showed lower gelatinization temperature, low viscosity, increased storage stability to temperature, time and thermal reversibility. The reheating of cooked paste deteriorates the properties of starch paste but the adhesive properties of hydroxyethyl starch were not affected. The introduction of hydroxyethyl group into starch significantly improved the dissolution ability of the films.     

Studies on Hydroxyethyl Starch. Part 1. A review of the chemistry of hydroxyethyl starch,with reference to its use as a blood plasma volume expander

The uses of hydroxyethyl starch have been recently extended by the proposals for its employment as a blood plasma volume expander and cryoprotective agent. These potential pharmacological uses for the derivative demand that its chemistry and biochemistry be thoroughly understood. This review examines the methods of preparing hydroxyethyl starch, the chemical composition of the product, its physical properties and the factors governing its resistance to starch-degrading enzymes.     

Influence of Water on Molecular and Morphological Structure of Various Starches and Starch Derivatives

In this study the influence of water on untreated, pregelatinised, and chemical modified starches was investigated. Because of their different botanical source, the starch products contain various quantities of amylose and amylopectin. The water vapour absorption capacity of the starches was studied by sorption/desorption and thermogravimetrical measurements. Higher absorption capacities were found for potato starch and for starches containing carboxymethyl and hydroxyethyl groups. Characteristic molecular differences found by Raman spectroscopy were evaluated for untreated and modified starches. To this end, the starch raw materials were classified into groups with similar pretreatments and properties based on cluster analysis. Additionally, the gelatinisation of starch‐water mixtures (gels, powders, and films) was continuously studied using temperature‐dependent Raman spectroscopy. In comparison with powder spectra, the Raman spectra of the starch films showed shifts in band positions in the range of the CH deformation and CH stretching modes. With the exceptions of high‐amylose maize starch and carboxymethylated starch, all starches form films. Starch films differ in their surface structures, water contact angles, and rates of water drop absorption, which might be caused by the different retrogradation properties. The swelling and shrinking behaviour of starch films was investigated at the morphological level by in situ environmental scanning electron microscopy (ESEM) experiments and evaluated by grey value analysis. Films of untreated starch show stronger swelling and shrinking than films of pregelatinised products.     

N,N‐Bis(2‐hydroxyethyl)formamide as a New Plasticizer for Thermoplastic Starch

N,N‐Bis(2‐hydroxyethyl)formamide (BHF) was synthesized efficiently and used as a new plasticizer for corn starch to prepare thermoplastic starch (TPS). The hydrogen bond interaction between BHF and starch was proven by Fourier‐transform infrared (FT‐IR) spectroscopy. As detected by scanning electron microscopy (SEM), starch granules were completely disrupted and a continuous phase was obtained. The crystallinity of corn starch and BHF‐plasticized TPS (BTPS) was characterized by X‐ray diffraction (XRD). The thermal behavior of glycerol‐plasticized TPS (GTPS) and BTPS was investigated by differential scanning calorimetry (DSC). The water resistance of BTPS was better than that of GTPS. Generally, at low relative humidity (RH), the tensile strength of BTPS was higher than that of GTPS. At high RH, the elongation at break of BTPS was higher than that of GTPS.