The Extrusion Cooking of Potato Starch Material

The effect of extrusion cooking on the pasting properties of potato starch materials is examined using a Couette rheometer. The dispersion viscosity of aqueous dispersions of potato starch, pregelatinized potato starch and commercial potato granules has been investigated. The effect of extrusion moisture and progress down the extruder on this property has been studied. The dispersion viscosity response is related to the gelatinization and disruption of starch granules. Extrusion at high moisture levels leads to high viscosity dispersions tending to that of gelatinized starch whereas low moisture levels result in lower viscosity dispersions.     

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。     

羟丙基马铃薯淀粉的羧甲基化影响因素研究

在环氧丙烷制备羟丙基马铃薯淀粉的基础上,再利用乙醇溶剂法对羟丙基马铃薯淀粉进行二次变性制得羟丙基羧甲基马铃薯淀粉。文中讨论氯乙酸用量、NaOH用量、反应时间、反应温度对羟丙基羧甲基马铃薯淀粉的取代度(DS)的影响,结果表明:羟丙基马铃薯淀粉羧甲基化的最佳条件为反应温度60℃,反应时间4 h,NaOH用量75%,氯乙酸用量65%。     

Kinetics of the Formations of Gelatinized and Melted Starch at Extrusion Cooking Conditions

Typical DSC thermograms of starch phase transition in the low moisture content range (15-40%) showed two thermal transition peaks. This suggests the existence of two different cooking mechanisms. We call them gelatinization and melting. “Gelatinization” describes thermal transition of starch with water and “melting” without water. Kinetics of the formation of gelatinized starch (GEL) and melted starch (MELT) were studied. Conversions caused by gelatinization and melting were separately analyzed by using information from DSC (Differential Scanning Calorimetry) isothermal studies. The rate of formation of gelatinized fraction followed first order kinetics and that of melted fraction zeroth order. The overall reaction rate followed zeroth order because melting is the dominant mechanism of the two under limited water contents of extrusion cooking conditions.     

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。     

玉米、木薯及马铃薯淀粉颗粒微晶结构及性质的研究

运用广角X射线衍射分析方法对玉米、木薯及马铃薯淀粉颗粒结晶结构及常温下水的溶胀作用对淀粉颗粒不同微晶结构的影响进行了系统研究,提出了在淀粉颗粒中存在着大量的介于微晶和非晶之间的亚微晶结构,并提供了在一条X射线衍射曲线图中确定微晶、亚微晶和非晶区域的方法。     

Kinetics of Starch Gelatinization During Extrusion Cooking

Ordinary corn (30% amylose) and waxy corn (1% amylose) were extruded at 17.8, 20, 30, 40 and 42.2% product moisture contents (d.b.) and extruder barrel temperatures of 116°, 120°, 140°, 160° and 164°C. Screw speeds of 93.5, 100, 130, 160 and 166.5 rpm were used to generate different residence times. The extruded products were evaluated for extent of starch gelatinization. Results indicate that the degree of gelatinization decreased with increasing moisture content but increased with increasing temperature. Starch gelatinization exhibited pseudo-zero-order reaction kinetics with higher rate constants for waxy corn than for high amylose corn. The rate constants decreased with decreasing temperature.     

单模聚焦微波辐射对马铃薯淀粉羧甲基化影响因素的研究

实验采用D iscover微波精确有机合成系统,采用单模聚焦微波辐射技术及电脑微控和空压气体同步冷却技术,以马铃薯淀粉为原料,并且以一氯乙酸为醚化剂,研究了单模聚焦微波辐射对马铃薯淀粉羧甲基化的影响。考察了在D iscover微波精确有机合成系统的标准模式下,设定最大微波辐射功率为100 W时,溶剂用量、微波碱化时间、微波醚化时间及反应物料配比对产品取代度和粘度的影响。通过正交实验确定最佳工艺条件:淀粉4.0 g,一氯乙酸2.4 g,氢氧化钠2.0 g,乙醇溶液体积为25 m l,最大辐射功率100 W,碱化辐射升温时间3 m in、控温时间2 m in,醚化辐射升温时间2 m in、控温时间4 m in。在此条件下可以快速获得较高取代度和粘度的羧甲基马铃薯淀粉。产品经红外光谱仪表征,证实与目标产物完全一致。     

Microscop of Rice Starch Granules During Cooking

Starch from five cultivars of rice was pasted in the Brabender viscograph and then held at 95°C for 60min. Granules were examined by light and scanning electron microscopy. In concentrated (12%) pastes, low-amylose rice starch showed total granule disintegration after 60min of cooking at 95°C, but highamylose granules showed only marginal disorganization. Waxy starch granules were disintegrated even at 70°C. In dilute (1%) pastes, on the other hand, granules swelled without appreciable disruption, apparently more in low than in high amylose starch. Clearly low amylose starch granules were weak and fragile and so swelled as well disintegrated easily, while high amylose rice starch was relatively strong and rigid and so resisted swelling as well as disintegration. This relative regidity/fragility of starch granules seemed to be the key to differences in rice quality.     

甘薯淀粉羧甲基化影响因素的研究

以甘薯淀粉为原料,用乙醇溶剂法制备了甘薯羧甲基淀粉钠,研究了氯乙酸、氢氧化钠、反应时间、反应温度、乙醇体积分数、乙醇溶液用量等因素对反应的影响.以黏度为目标,用正交实验方法确定了最佳工艺条件为:甘薯淀粉用量10 g、氢氧化钠7 g、氯乙酸6.5 g、乙醇体积分数75%、乙醇65 ml、反应温度50℃、反应时间95 min.在该优化条件下,甘薯羧甲基淀粉取代度(DS)达0.67,黏度达3.6 Pa·s.     

干法羧甲基化反应对玉米淀粉颗粒性质影响的研究

以玉米淀粉为原料,干法制备羧甲基淀粉,并利用红外光谱仪、扫描电子显微镜和X-射线衍射仪对不同取代度的羧甲基淀粉的分子结构、颗粒形貌及结晶性进行了研究。结果表明：干法羧甲基化反应使玉米淀粉分子结构改变,结晶程度降低,淀粉颗粒膨胀,颗粒表面变形、破裂。随取代度提高,反应对淀粉颗粒的破坏程度增大。     

Inner Structure of Potato Starch Granules

A combination treatment (dry-heat and glucoamylase) was applied on potato starch granules. Many inner granules in the granules after the treatments were observed by SEM. The inner granule located near edge of ellipsoid of granule was partially degraded X-ray diffraction pattern of starch granules did not change before and after the treatments in spite of over 50% loss by amylase digestion. GPC and iodine reaction of the sample showed the treatments brought about fairly large degradation of both amylopectin and amylose components, but GPC of debranched sample after the combination treatments showed amylose was thoroughly degraded while peaks pattern of amylopectin did not change. Small size granules were more susceptible than large size granules by the treatments.     

Studies on the Biosynthesis of Starch Granules. Part 7. Compound Granules in Potato Starch

The nature of compound starch granules in potato starch is examined. The relevance of this investigation to the possible formation of potato starch is discussed, and a mechanism for synthesis of compound granules proposed.     

Extrusion Cooking in Enzymatic Liquefaction of Wheat Starch

Wheat starch was treated for gelatinization, partial liquefaction, and subsequent further hydrolysis by extrusion cooking together with a thermostable Bacillus licheniformis α-amylase followed by batch incubation of the extrudates at 80°C. The degree of hydrolysis depended on the extrusion feed moisture content, enzyme concentration, mass temperature during extrusion cooking, and the length of the counter screw elements. The degree of hydrolysis was followed both by dextrose equivalent and by molecular weight distribution pattern as determined by high performance gel permeation chromatography. A reaction velocity model was shown to fit well to the kinetic data obtained. The enzyme was only incompletely inactivated by mercuric chloride suggesting the presence of also other than sulfhydryl dependent amylase.     

Extrusion Cooking of Cassava Starch for Ethanol Production

Response surface methodology was used to study the effect of extrusion variables on gelatinization and viscosity of cassava starch with the aim to reduce energy consumption in alcohol production. None of the variables significantly affected the degree of gelatinization and moisture content of starch was the only significant variable affecting cold viscosity. Torque was affected by all the variables moisture being the most important. Extrusion was an efficient pre-treatment for simultaneous saccharification and fermentation of cassava starch, resulting in 92.4% ethanol conversion. The best conditions for continuous process were: 100°C. 70 rpm, 4 mm die opening and 25-27% moisture. For discontinuous process, when the extruded starch would be dried and ground 200°C, 190 rpm, 4 mm die opening and 20% moisture is recommended.     

Production of Resistant Starch by Extrusion Cooking of Acid-Modified Normal-Maize Starch

ABSTRACT:  The objective of this study was to utilize extrusion cooking and hydrothermal treatment to produce resistant starch (RS) as an economical alternative to a batch-cooking process. A hydrothermal treatment (110 °C, 3 d) of batch-cooked and extruded starch samples facilitated propagation of heat-stable starch crystallites and increased the RS contents from 2.1% to 7.7% up to 17.4% determined using AOAC Method 991.43 for total dietary fiber. When starch samples were batch cooked and hydrothermally treated at a moisture content below 70%, acid-modified normal-maize starch (AMMS) produced a greater RS content than did native normal-maize starch (NMS). This was attributed to the partially hydrolyzed, smaller molecules in the AMMS, which had greater mobility and freedom than the larger molecules in the NMS. The RS contents of the batch-cooked and extruded AMMS products after the hydrothermal treatment were similar. A freezing treatment of the AMMS samples at −20 °C prior to the hydrothermal treatment did not increase the RS content. The DSC thermograms and the X-ray diffractograms showed that retrograded amylose and crystalline starch–lipid complex, which had melting temperatures above 100 °C, accounted for the RS contents.     

Effect of Extrusion Cooking on Molecular Parameters of Corn Starch

By using a systems analytical model (SAM) and a fuzzy logic control software (fuzzy CIM) extrusion experiments were designed, that enabled a differentiation of the influence of the thermal energy input, expressed by the product temperature (PT), and the influence of the specific mechanical energy input (SME) on the molecular structure of extruded starch. The chromatographic examination of the molecular changes in the starch clearly revealed the influence of the extrusion cooking conditions on molecular degradation. The molecular size of extruded starch, expressed as the weight average of the molecular weight (M̄ _w), decreased exponentially when SME increased. In the range of 110—180 °C, PT had no significant influence on M̄ _w so that the observed reduction of M̄ _w was primarily dependent on the increase in SME. By contrast, the polydispersity depended both on PT and SME. The influence of PT on the polydispersity was of minor significance up to 160 °C, increasing more steeply at higher temperatures. PT increase above 180 °C resulted in increasing reducing power of the extruded starch, whereas SME had almost no effect on reducing power. Only at a PT of more than 180 °C small amounts of short chain molecules with a degree of polymerisation (DP) smaller than 6 could be determined.     

非晶颗粒态马铃薯淀粉的制备方法

报道了水分散体系高温溶胀、常温碱分散体系强碱溶胀作用非晶颗粒态马铃薯淀粉的制备方法 ,采用偏光显微镜对多晶态向非晶态的变化进行了确认 ,提出在一定条件下 ,高交联马铃薯淀粉 ,可以由原淀粉多晶颗粒态制备成只含无定形结构的非晶颗粒态淀粉     

三氯氧磷交联马铃薯淀粉颗粒膨胀历程及溶胀机理研究

利用淀粉与三氯氧磷的交联反应 ,通过控制交联反应程度 ,成功地控制了交联淀粉颗粒的膨胀并使其停留在不同的溶胀阶段。本文详细地研究了处在不同溶胀阶段交联淀粉颗粒的结构特征和变化趋势 ,揭示了交联淀粉颗粒由高交联非糊化到低交联溶胀糊化的膨胀历程及溶胀机理 ,即交联马铃薯淀粉是以颗粒尾端为主的不均衡膨胀。