反应挤出法在酯化淀粉生产中的应用

反应挤出法作为淀粉干法改性中的一种新方法,在淀粉改性中有可连续生产、生产效率高、产品的成本低、技术含量高、利润高等优点。主要介绍了反应挤出的原理及其特点,对传统方法和反应挤出法生产酯化淀粉进行了对比。与传统的湿法和干法工艺相比,反应挤出法是酯化淀粉生产中一种经济可行的方法。     

反应挤出技术在变性淀粉生产中的应用

主要阐述了反应挤出的原理和特点，并且概括了当前用反应挤出法生产氧化、酯化、接枝、交联和醚化等变性淀粉的现状。认为反应挤出技术是变性淀粉生产中一种经济可行的方法。     

反应挤出与酶法联合制备多孔淀粉工艺的优化

以多孔淀粉吸油率为指标,利用Placket-Burman Design(PBD)试验、最陡爬坡试验和Box-Benhnken Design(BBD)试验对反应挤出与酶联合作用制备多孔淀粉工艺进行优化。结果表明,PBD试验得出影响多孔淀粉显著效应因素为物料水分含量、α-淀粉酶添加量、酶解时间、糖化酶添加量。通过最陡爬坡试验确定粉吸油率的九个因素进行评价,筛选出四个最大响应区域,并采用BBD试验优化了工艺。得出最佳配方工艺:物料水分含量36%、α-淀粉酶添加量0.52%、酶解时间7.7 h、糖化酶添加量1.73%,挤压温度70 ℃、螺杆转速120 r/min、pH5.0、酶解温度50 ℃、底物浓度25%,吸油率达到最大值68.49%,与预测值相近,较对照提高14.97%。扫描电子显微镜显示,反应挤出与酶联合作用与天然淀粉酶解法相比,其制备的多孔淀粉在孔的数量、孔径大小、分布均一性等方面都有着明显的优势。     

甘薯淀粉磷酸酯制备的反应动力学

研究制备甘薯淀粉磷酸酯的反应动力学过程,建立三偏磷酸钠浓度与反应温度、反应时间之间的动力学模型:cA=c0e-1.18×1013×e-1.12×104×1/T×t。结果表明:该模型预测值与实测值吻合良好。     

淀粉及变性淀粉颗粒形貌结构的研究

通过扫描电子显微镜观察了各种原淀粉及其经过不同处理方式得到的变性淀粉的颗粒形貌结构,发现运用不同的处理方式得到的淀粉与原淀粉具有不同的颗粒形貌结构并具有一定的规律性,为判断未知变性淀粉样品的处理方式提供了一定的依据。     

螺杆挤出热塑性淀粉黏度特性研究

本研究以普通玉米淀粉为主要原料,以甘油为增塑剂,采用双螺杆挤出法制备热塑性淀粉,考察了甘油/淀粉质量比、挤压机三区温度和螺杆转速3个因素对热塑性淀粉的挤出扭矩和糊化性质的影响,从热塑性淀粉熔体和热塑性淀粉糊两个方面分析了热塑性淀粉的黏度特性.     

Changes in Starch and Protein on Extrusion of Corn Starch and Sunflower Protein Blends

We investigated the use of electron spin resonance spectroscopy (ESR) and the spin labelled fatty acid, 16 doxylstearic acid (16-DSA) in the study of starch and protein modification during extrusion processing of corn starch (CS), corn meal (CM), and their blends with sunflower protein isolate (SPI). Spectra due to binding of the spin probe to starch and protein were identified. Changes in spectra after extrusion of all materials indicated that: (1) ~90% of the starch was modified (gelatinized); (2) The globular protein structure was disrupted. These changes demonstrate that spin probes and ESR spectroscopy may be used to study starch and protein modification during extrusion and other food processes.     

蒸煮挤压过程中淀粉的变化

研究了挤压过程中，挤压温度、螺杆转速、进料速度、原料水分含量对淀粉的糊化、降解及对挤出物的溶解指数和膨化度的影响。     

响应面试验优化挤出酶解复合法改性玉米淀粉工艺

利用挤出酶解对玉米淀粉进行改性,采用响应面法对影响改性工艺的主要因素耐高温α-淀粉酶添加量、挤出温度、玉米淀粉含量进行优化,通过高效液相色谱、扫描电子显微镜、X-射线衍射以及差示扫描量热仪对玉米淀粉挤出酶解复合改性前后的低聚糖组成、表观结构、结晶度以及热力学性质的变化进行分析。结果表明：当耐高温α-淀粉酶添加量40 U/g、挤出温度140 ℃、玉米淀粉含量70%时,挤出改性玉米淀粉葡萄糖当量值为19.55%。高效液相色谱分析表明挤出物低聚糖的组分能够得到较好的分离,低聚糖样品中各组分葡萄糖、麦芽糖、麦芽三糖、麦芽四糖、麦芽五糖的质量比为1.0∶3.4∶7.5∶6.0∶1.8。玉米淀粉经挤出酶解复合改性后颗粒表面出现孔洞,结晶度下降。     

Impacts of Cellulose Fiber Particle Size and Starch Type on Expansion During Extrusion Processing

Objective of this study was to understand the impacts of cellulose fiber with different particle size distributions, and starches with different molecular weights, on the expansion of direct expanded products. Fiber with 3 different particle size distributions (<125, 150 to 250, 300 to 425 μm) and 4 types of starches representing different amylose contents (0%, 23%, 50%, and 70%) were investigated. Feed moisture content (18 ± 0.5 % w.b) and extruder temperature (140 °C) were kept constant and only the extruder screw speed was varied (100, 175, and 250 rpm) to achieve different specific mechanical energy inputs. Fiber particle size and starch type significantly influenced the various product parameters. In general, the smaller fiber particle size resulted in extrudate with higher expansion ratio. Starch with an amylose: amylopectin ratio of 23:77 resulted in highest expansion compared to the other starches, when no fiber was added. Interestingly, starch with 50:50, amylose: amylopectin ratio in combination with smaller fiber particles resulted in product with significantly greater expansion than the control starch extrudates. Aggregation of fiber and shrinkage of surface was observed in the Scanning Electron Microscope images at 10% fiber level. The results suggest the presence of active interactions between the cellulose fiber particles and corn starch molecules during the expansion process. A better understanding of these interactions can help in the development of high fiber extruded products with better expansion.     

Shear Induced Starch Conversion During Extrusion

Using a capillary rheometer and a singlerscrew extruder, waxy corn starch was extruded at a relatively low temperature range. Notable conversions induced by shear energy were obtained in very short residence times (from several sec to 1 min). Conversions up to > 70% were also achieved. Kinetic studies showed that conversion caused by shear energy was more efficient than that by thermal energy. The shear rate constant, k, was an exponential function of shear stress and a linear function of shear rate. The minimum shear stress required to cause starch conversion was from 10⁴ to 10⁶ N/m² for 100°C to 21°C. In such “shear” experiments, the maximum temperature rise due to viscous thermal dissipation, measured experimentally and calculated theoretically, was too low to cause any significant thermal cooking of starch. The shear converted starch extrudates were unpuffed and had shapes of traditional pasta.     

双螺杆挤压制备酯化玉米淀粉的实验研究

以玉米淀粉为原料,醋酸乙烯酯为酯化剂,用双螺杆挤压机制备酯化淀粉。研究了各反应因素对产品取代度(DS)的影响,并以DS为指标,通过正交实验确定了其最佳工艺条件:挤压温度90℃,螺杆转速80r/min,反应体系pH值9.5,酯化剂浓度2%,物料含水率30%。对产品的糊化性和凝沉性等理化性质做了测定和分析。     

挤压膨化过程中物料组分的变化分析

挤压膨化加工广泛应用于食品加工业。挤压膨化过程中，物料组分发生了复杂的物化变化。在高温、高压、高剪切力环境下，淀粉分子间的氢键断裂，淀粉发生糊化、降解，生成小分子量物质，淀粉水溶性增强；蛋白质发生变性、重组，发生组织化，蛋白质水溶性和生物学效价下降；脂肪与淀粉以及蛋白质形成脂肪复合体，淀粉溶解性和消化率降低，脂肪氧化速度减慢，氧化程度减小，产品货架期延长。