Effects of Annealing and Additives on the Gelatinization,Structure, and Textural Characteristics of Corn Starch

The effects of additives (sucrose, glucose, and sodium chloride) on textural properties of native and annealed corn starch gels were measured using differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and texture analyzer. Annealing temperature, additive concentration, and pH affected the corn starch gels. Firmness, consistency, cohesiveness, and viscosity values ranged from 20.55 to 43.70 g, 213.67 to 412.00 g/sec, –25.81 to –15.22 g, and –104.21 to –6.73 g/sec, respectively. The eigenvalue of the texture characteristics of annealed corn starch decreased without additives, and increased with additives. Annealing at 55°C had more effect than did annealing at 45°C.     

Gelatinization Characteristics of a Cassava/Corn Starch Based Blend during Extrusion Cooking Employing Response Surface Methodology

The gelatinization characteristics of a cassava/corn starch based blend with relatively high moisture content during cooking extrusion were studied. The study was carried out by using Response Surface Methodology. The results showed that the die temperature T_d (°C) was the main influencing factor for the starch gelatinization, and the feed rate of the materials V_f (g/min) was another minor one. Because of the high material moisture content during extrusion the moisture content M_c (%) influenced the gelatinization degree not so obviously. The residence time distribution of the mass during extrusion were studied as well as discussed as a influencing factor on the gelatinization results.     

Transformation and Balance of Cyanogenic Compounds in the Cassava Starch Manufacturing Process

The balance of total cyanogenic compounds and distribution of each compound including bound cyanide, cyanohydrin and free cyanide were evaluated in a cassava starch factory, having a production capacity around 100 t starch per day. The production of starch began with transferring washed roots to the rasper, followed by a series of extractors, separators, dewatering centrifuge and flash dryer, with an average water consumption of 11.4 t per ton dry starch. The total amount of cyanogenic compounds entering the process varied from 28 to 43 kg HCN equivalent per day, depending on the root quality. In roots, 64% of bound cyanide was primarily found and it significantly decreased to 22% after rasping whereas the cyanohydrin content increased from 34% to 62%. Most of cyanogenic compounds, predominantly present as cyanohydrin (55 to 70%), was discharged in liquid and solid wastes, accounting for 92% and 5% of total cyanide in roots, respectively. Only a negligible amount of cyanogenic compounds remained in the starch products, having less than 2 mg HCN equivalent per kilogram dry starch. Typically, water from the separators with 91% total cyanide content was recycled to the root washer before being discharged as wastewater, whereas the liquid from the coarse extractor (43% of total cyanide) was recycled to the rasper. This could cause the accumulation of cyanogen in the process and, therefore, in the finished products. With knowledge of the balance and transformation of cyanogens in starch processing, it is possible to assure the quality of low‐cyanide starch by modifying starch process features such as water circulation and pH adjustment.     

接枝玉米淀粉浆料的制备与性能研究

制备了一种利于环保、性能优良的接枝玉米淀粉浆料 ,通过红外光谱和扫描电镜对其结构和表面形貌进行了分析 ,并对其浆纱性能进行了测试。结果表明 :该浆料糊化性能良好、浆液稳定 ,与乳液共聚浆料配合使用对T/C 6 5 / 35 13 1tex纱上浆 ,可替代原配方中 80 %的PVA浆料 ,且浆纱性能优良。     

Glycemic Potential of Extruded Barley,Cassava, Corn,and Quinoa Enriched With Whey Proteins and Cashew Pulp

Adding whey protein concentrate (WPC80) and cashew pulp (CP) to extruded snacks can reduce overall carbohydrate content. In this study, barley, cassava, corn meal and quinoa were blended with WPC80 (12.5 wt%) or with CP (12.5 wt%), then extruded and baked. The products' rapidly available glucose values or potential glycemic index were: quinoa (70%), barley (61%), corn (54%), and cassava (48%). Adding WPC80 with or without CP improved the glycemic potential values for barley and quinoa, but not for cassava, which increased from 61 to 77%. Adding WPC80 or CP had no effect on corn products.     

Chemical and Functional Properties of Phaseolus lunatus and Manihot esculenta Starch Blends

Chemical and functional characteristics were determined for Phaseolus lunatus (P) and Manihot esculenta (M) starches, and blends of these two starches (25P/75M, 50P/50M, 75P/25M (%, w/w)). Starch purity varied from 95 to 98%. The lowest amylose content was in M. esculenta (17.3%) and the highest in P. lunatus (32.4%) with the blends having intermediate values. Total dietary fiber content in M. esculenta was 1.7%, and 1.2% in P. lunatus; of the blends the 25P/75M had the highest percentage (2.3%). Initial gelatinization temperature was higher for P. lunatus (67.9°C) than for M. esculenta (57.6°C), with the blends having intermediate values. P. lunatus starch had the highest retrogradation value (8.3 mL/50 g starch) of all the starches, while M. esculenta and the 25P/75M blend had no retrogradation at all. The P. lunatus paste had the highest viscosity (125.5 mPa s) compared to the other pastes, which were statistically similar (P>0.05). Gel clarity was lower in P. lunatus (23.84%T) than in M. esculenta (51.76%T), with intermediate values in the blends. The 25P/75M blend was selected as having the best combination of characteristics, since it showed not retrogradation, had high viscosity (102 mPa s), and was stable in the heating‐cooling cycle. This makes it a starch with suitable functional properties for use in a variety of foods. These results suggest that blending native starches from different vegetable sources improves their properties.     

两性淀粉浆料的制备及性能研究

研究采用湿法双醚化和氧化降解制备的季铵型羧甲基两性淀粉浆料性能。试验制备了季铵型羧甲基两性淀粉,测试了不同黏度、取代度、pH值条件下两性淀粉的浆液及浆膜性能,并比较了阳离子淀粉、羧甲基淀粉和两性淀粉的浆膜性能以及对纯棉纱和涤棉纱黏附性。结果表明:两性淀粉具有高浓低黏浆料特征,其黏度热稳定性和成膜性良好;随着黏度下降,浆膜断裂强度及断裂伸长率降低;随着阴、阳离子取代度的增加,浆料黏度热稳定性逐步提高,阳离子取代度在0.02~0.03、阴离子取代度在0.03~0.04范围内的两性淀粉浆膜性能较理想;pH值在中性条件下,浆膜断裂强度较好;两性淀粉的浆膜性能均优于阳离子淀粉及羧甲基淀粉;两性淀粉浆料对棉纱、涤棉纱的黏附性能优于其他变性淀粉浆料。认为:季铵型羧甲基两性淀粉能够满足纯棉纱和涤棉纱的上浆要求。     

响应曲面法优化玉米谷蛋白凝胶制备工艺的研究

本研究通过单因素试验和响应曲面法,优化了玉米谷蛋白凝胶制备工艺。以加热温度、加热时间、氯化钠添加量为因素,以凝胶硬度、内聚性、胶凝性和咀嚼性为响应值对实验进行响应面设计,建立了凝胶硬度、内聚性、胶凝性和咀嚼性的回归模型,优化得到最佳工艺条件为加热温度91.33℃、加热时间64.04min、氯化钠添加量8.25%。     

Crystallinity,Thermal and Morphological Characteristics of Resistant Starch Type III Produced by Hydrothermal Treatment of Debranched Cassava Starch

Cassava starch was debranched using pullulanase and the linear glucans recrystallized by incubation at 60°C or by temperature cycling at 120/60°C, and further subjected to heat‐moisture treatment (HMT). Resistant starch (RS III) contents increased from 21.4 g/100 g in the debranched starch (DS) to 67.3 g/100 g in the debranched starch incubated at 60°C (DRS) and 47.8 g/100 g in the debranched starch subjected to temperature cycling (DCS), and further to 84.8 g/100 g and 88.4% g/100 g in HMT‐DRS and HMT‐DCS, respectively. Total crystallinity varied between 31.4‐59.8% and the crystalline type was C in DS and DRS and A in DCS, HMT‐DRS and HMT‐DCS. The melting properties were characterized by broad endotherms, but the exact melting region and enthalpy were dependent on recrystallization method. The main endothermic peaks of DS and DRS occurred at 103.9 and 109.8°C, respectively, whereas DCS exhibited split endotherms at 113.6 and 138.1°C. Heat‐moisture treatment broadened the endotherms and increased their enthalpies. Scanning electron micrographs revealed surface topography differences related to size and aggregation of individual crystalline bodies.     

Effects of Compositional and Granular Properties on the Pasting Viscosity of Rice Starch Blends

The changes in swelling power and pasting properties of suspensions of starch blends were studied in dependence on starch composition and at various isothermal temperatures (T_iso). Samples were prepared by mixing rice starches from Kaoshiung Sen 7 (KSS7, a high‐amylose‐content variety) and Taichung waxy 70 (TCW70, a waxy variety). Generally, mixing these starches at a comparable ratio caused significant decrements in overall swelling power, onset temperature of gelatinization or viscosity rise, and final viscosity of hot pastes after 30 min of isothermal stirring. Notable increases in the peak and conclusion temperatures of gelatinization and in the peak viscosity of the pastes were also observed. Generally, all viscosity parameters of the blends showed two linear dependencies on the starch composition, the graphs intersecting at a critical starch composition depending on the parameters concerned. The onset temperature of viscosity increase was related to the volume fraction of swollen granules when they were just closely packed in suspension. The volume fraction of KSS granules was smaller than that of TCW70. In addition, the rate of viscosity increase and the peak viscosity of the starch suspensions could be well described in terms of the swelling power (Q) when Q ≤ ∼27, and depending on the T_iso examined. From the photomicrographs of starch suspensions, the extensive shear‐induced disintegration of TCW70 granules in the co‐existence of rigid KSS7 granules was evident and in turn responsible for the reduced final viscosities of the hot pastes obtained from starch blends.     

Process Optimization by Response Surface Methodology and Characteristics Investigation of Corn Extrudate Fortified with Yam (Dioscorea alata L.)

Response surface methodology was used to investigate the optimum operation conditions of a single screw extruder and to analyze the effects of extrusion processing variables, including yam flour contents (10–30 %), moisture content (10–18 %), and screw speed (250–350 rpm) on characteristics of the corn–yam extrudates. Quadratic polynomial equations were also obtained by multiple regression analysis. The predicted models were adequate based on the lack-of-fit test and coefficient of determination obtained. By superimposing individual contour plots of the different responses, regions meeting the optimum conditions were also derived. The moisture content had critical effect on all responses variables. All the characteristic of the corn–yam extrudates evaluated were significantly affected by three process variables. Feed moisture content was the most significant variable with on most of characteristics. Increasing moisture content caused increase in bulk density, water absorption index and hardness, but decrease in radial expansion ratio. However, graphical optimization studies resulted in 21–23 %, 12–13 %, and 305–320 rpm of yam flour level, moisture content, and screw speed, respectively. The results suggested that corn extrudates fortified with yam produced by using the single-screw extruder are suitable for snack food development.     

Morphological,Thermal, Pasting,and Rheological Properties of Barley Starch and Their Blends

Native barley starch, as well as its blends with corn, wheat, and rice starch at different ratios of 75:25, 50:50, 25:75 were examined in terms of morphology, thermal, pasting, rheological, and retrogradation properties. Amylose content varied between 10.9–41.4% in rice, corn, wheat, and barley while it ranged from 18.02–38.40% in blends of barley starch with rice, corn, and wheat. A rapid visco analyzer showed that barley starch and its blends having low amylose content exhibited higher peak viscosity, breakdown, and setback than the high-amylose-containing starches and their blends. Amylose content was found to be negatively correlated with swelling power while it exhibited nonlinear relationship with solubility index. The transmittance of starch suspension stored at 4°C decreased during storage up to 6 days. Barley starch granules were largest (<110 μm) in size followed by wheat (<30 μm), corn (<25μm) and rice (<20μm) starches. Gelatinization temperatures (To, Tp, Tc) and enthalpies of gelatinization (ΔHgel) of starches from different sources also differed significantly. Corn and rice starches showed higher transition temperatures in general than those from wheat and barley; however, they showed higher ΔHgel values. Barley starch showed a higher tendency towards retrogradation than the cereal starches. Barley starch showed highest peak G′, G″ and lower tan Ð than corn, rice and wheat starches during the heating cycle. This study showed that the magnitude of changes in their properties during blending depends on the amylase content and morphological characteristics.     

Influence of Cassava Storage Root Development and Environmental Conditions on Starch Granule Size Distribution

Among starch producing crops, cassava has a higher carbohydrate production than others under suboptimal conditions, more than 163×10⁶ t of cassava starch are produced world‐wide each year and are used for direct human consumption, animal feeds and as raw material for a wide range of industrial products. A basic knowledge of starch characteristics and storage process is required to improve cassava starch quality and quantity. This report describes a comparative study of morphology, starch granule size distribution and amylose content in cassava storage roots grown under different conditions. Microscopic evaluation reveals that storage roots contain larger starch granules than fibrous roots. The study on three Asian cassava cultivars demonstrates the increment of starch granule size from outermost to innermost layers of storage root, while no significant change is observed in amylose content. The effects of developmental stage and growing season on cassava starch reveals that granule size is significantly influenced by both factors, while the amylose contents only fluctuate in a narrow range. The size of the starch granules increases particularly in the first six months after cultivation. Planting cassava in the beginning of the wet season in Asia yields larger granule sizes than planting in the dry season. The significance of this study lies in better understanding optimal growing conditions for improved starch characteristics and production, leading to a better quality agricultural production of this important food and materials crop.     

木薯变性淀粉对猪肉肌原纤维蛋白凝胶质构、流变及热力学特性的影响

本实验研究了不同比例的木薯变性淀粉对猪肉肌原纤维蛋白(MP)凝胶特性的影响。分析了凝胶质构、静态流变和热力学特性的变化。结果显示:添加10%的木薯变性淀粉增加了蛋白凝胶的弹性,而凝胶的硬度、强度、内聚性、咀嚼性和胶黏性相对适中,从而改善凝胶的质构特性;通过差示扫描量热仪(Differential scanning calorimetry,DSC)分析发现木薯变性淀粉添加量为10%时,降低了蛋白的热相变温度和焓值,促进蛋白变性;另外,木薯变性淀粉的添加也改变了凝胶的表观粘度及触变环面积。当木薯淀粉添加量为10%时,凝胶的表观粘度和触变环面积最小,改善了凝胶的塑性能力及流变稳定性。     

Response Surface Methodology for the Optimization and Characterization of Cassava Starch‐graft‐Poly(acrylamide)

Response surface methodology (RSM) was employed for the synthesis of cassava starch‐graft‐poly(acrylamide) using ceric ammonium nitrate as free radical initiator. Concentration of acrylamide, concentration of ceric ammonium nitrate, reaction temperature and duration of reaction were optimized using a 4‐factor 3‐level Box‐Behnken design. The dependent variables were percentage grafting (%G) and grafting efficiency (GE). Second order polynomial relationships were obtained for %G and GE, which explained the main, quadratic and interaction effects of factors. The highest%G and GE obtained were 174.8% and 90.7%, respectively. The optimum values of parameters predicted through RSM were 20 g acrylamide/10 g dry starch, 3.3 g/L ceric ammonium nitrate, 180 min reaction duration and 45ºC temperature with a %G of 190.0. For GE, the predicted levels of factors for the optimum value of 90.8% were 17.5 g acrylamide/10 g dry starch, 4.1 g/L ceric ammonium nitrate, 180 min reaction duration and 55ºC temperature. The graft reaction was confirmed by FTIR analysis, where the absorption bands corresponding to the C=O stretching and N‐H bending of the –CONH₂ group were observed. Scanning electron microscopic studies on grafted starches revealed that the granular structure of the starch was affected by the reaction. X‐ray diffraction analysis showed that the crystallinity of starch was decreased as a result of grafting and the reduction was higher for the grafted starches with higher percentage grafting.     

基于响应面法氧化辛烯基琥珀酸糯玉米淀粉酯制备的优化研究

以糯玉米淀粉为原料,先对其氧化处理,然后用辛烯基琥珀酸酐对氧化淀粉进行酯化.在单因素基础上选取影响酯化取代度明显的四个因素(pH值、反应温度、淀粉乳浓度、反应时间)在酸酐加入量为3%及酸酐用乙醇稀释5倍的前提下进行响应面设计,得出了最优条件:pH值为8.4,反应温度为36%,淀粉乳质量分数为40%,反应时间为3.5 h,酯化剂用量3%(占淀粉干基比),此时制备产品的取代度可达0.0196.     

Connection Between Surface Properties,Specific Surface Area and Component Distribution of Binary Mixtures of Corn Starch and Metronidazole

Knowledge of the surface properties of pharmaceutical solids and excipients is of great significance for an understanding of the interactions between the particles of powders and powder mixtures [1, 2] and the accessories of the equipment [3] in the course of various technological procedures, e.g. powder mixing. The mixing of particulate ingredients to achieve content uniformity remains an important question [4]. Our present aims were to investigate the interparticular interactions, the specific surface areas of binary mixtures and of their components, and the visual appearance of the binary mixtures, using a scanning electron microscope. Corn starch is a frequently used excipient in pharmaceutical formulation. Metronidazole is one of the active agents with high dose. To find the optimal active ingredient and excipient proportion with homogeneous distribution is in this case a very important question. Surface free energy, adhesion and cohesion work may be calculated in various simply ways. In view of the surface properties of a binary mixture and that of the components the particle distribution can be characterized.     

Evaluation of Starch Degradation and Textural Characteristics of Dietary Fiber Enriched Biscuits

Abstract

The effects of dietary fiber inclusion on biscuit texture, cooking properties, and sugar release after in vitro degradation were investigated. Inulin, β-glucan enriched fraction (BGEF), potato fiber, and a resistant starch were used. Effects of the dietary fibers on the pasting properties of flour based mixtures were investigated using a rapid visco analyzer. Results showed a reduction in visco-pasting properties (peak viscosity and final viscosity) of the flour–dietary fiber systems with increasing fiber content. Addition of dietary fiber into the biscuits affected biscuit shrinkage and height development during cooking, as well as generally reducing the resistance of biscuits to snapping during texture analysis tests. Sugar release during in vitro degradation studies showed a highly significant decline when comparing dietary fiber enriched biscuits to the control samples. This would have a beneficial effect in potentially reducing the glycaemic index and subsequent glycaemic loading of such foods.     

慈姑、荸荠和菱角淀粉共混物的凝胶特性研究

慈姑、荸荠和菱角均为南方特色水生根茎类作物,具有独特的加工特性,其混粉制品拥有新的凝胶特点和营养价值。本试验采用混料设计,建立了凝胶质构指标与混合淀粉各组分的回归模型,并采用差示扫描量热法测定混粉糊化过程中的热特性,在二者基础上探讨各组分间的交互作用。结果表明,混粉既表现出慈姑淀粉的拮抗效应,也表现出菱角淀粉的增效效应,这两种作用相互制约,最终在各凝胶质构特征参数上表现出占优势的一种。DSC图中吸热峰的叠加,表明混合淀粉发生了共糊化。慈姑、荸荠淀粉的存在,明显抑制了菱角淀粉的回生,菱角淀粉颗粒相对可利用的水分少,膨胀受限,仅能部分膨胀,贮藏过程中的脱水收缩作用减弱。模型的建立对于优化各淀粉组分比例而获得所需的凝胶特性具有指导意义,该研究可为南方特色淀粉资源的有效利用提供参考。     

Glass Transition of Extruded Wheat,Corn and Rice Starch

Commercial wheat, corn and rice starch were extrusion cooked under a specific mechanical energy input (SME) ranging from 81 to 365 Wh/kg (288 to 1314 kJ/kg). Extrusion cooking at low and high SME resulted in products having significant differences in molecular weight distribution and having crystalline structures of the V‐ and E‐type, as determined by gel permeation chromatography and X‐ray diffraction analysis. Differential scanning calorimetry revealed that the glass transition temperature (T_g) of the extruded starches was independent of the botanical source, the degree of extrusion‐induced molecular fragmentation and the formation of the V‐ and E‐type crystalline structures. The obtained master curve, defined by the relationship between water content and T_g of the amorphous starch, may be used as a predictive tool in modelling the extrusion process of starch or starch containing blends, especially with regard to the formation of the morphological structure and texture attributes of directly expanded products.