天然的,物理和化学改性的面包果淀粉的功能特性

淀粉从面包果中分离出来,它通过氧化、乙酰化、热湿处理和退火作用而深度改性。研究了天然和改性淀粉的功能特性,近似分析表明,通过退火、氧化和乙酰化作用改性的淀粉比天然淀粉有较高的湿度,而通过热湿作用改性的淀粉有较低的湿度。除了天然淀粉和退火淀粉有相同的天然纤维含量(042％)之外,其它改性淀粉的天然纤维含量均降低。通过改性之后,蛋白质和脂肪含量也降低了。乙酰化、氧化和热处理作用提高了天然淀粉的膨胀力。     

红薯/玉米淀粉共混物糊、流变及热力学性质研究

以不同质量比(0100,2575,5050,7525,1000)的红薯/玉米淀粉混合物为原料,用不同试验方法研究其糊化及流变学特征。布拉班德糊化结果表明:玉米淀粉成糊温度(77.7℃)高于红薯淀粉(73.2℃),红薯淀粉峰值黏度(513BU)大于玉米淀粉(281BU),混合淀粉的崩解值及回生值介于单一种类淀粉之间;动态频率扫描结果表明:玉米淀粉的储能模量约是红薯淀粉的4倍,混合淀粉的模量介于单一品种淀粉之间,均为弱凝胶;稳态流变曲线表明:被测样品符合Herschel-Bulkley模型,均为非牛顿型流体,相较于单一淀粉,红薯/玉米淀粉混合物触变性假塑性更强。剪切结构恢复力结果表明:红薯/玉米混合物淀粉凝胶抗剪切能力低于玉米淀粉。差示扫描量热(Differential scanning calorimetry,DSC)测定结果表明:玉米淀粉具有较高的热焓值,红薯/玉米混合淀粉热焓值降低。     

离子液体中酶催化合成硬脂酸淀粉酯及其流变学特性研究

以1-丁基-3-甲基咪唑醋酸盐（[BMIM]Ac）和1-丁基-3-甲基咪唑四氟硼酸盐（[BMIM]BF4）的混合离子液体为介质,脂肪酶催化淀粉硬脂酸甲酯合成硬脂酸淀粉酯,并采用核磁共振（1H NMR）、X-射线衍射对其进行结构表征。通过快速黏度仪及动态流变仪分析了硬脂酸淀粉酯的流变学特性。结果表明:和原淀粉相比,硬脂酸淀粉酯的峰值黏度显著降低,并随着取代度的增大,黏度呈下降趋势;动态流变学测定结果显示酯化后的淀粉储能模量和损失模量比原淀粉显著下降（p<0.05）;静态流变学测定结果显示淀粉（包括酯化淀粉）为非牛顿流体,出现了剪切稀化的现象,且取代度越高,黏度越低,表明长链硬脂酸基团的引入,削弱了淀粉分子之间氢键作用。      

磷酸酯化多孔淀粉的流变学性质

淀粉糊流变性质是影响淀粉类产品加工品质的主要因素,采用流变仪研究了不同取代度的磷酸酯化多孔淀粉糊的流变学性质。结果表明:所有样品均呈现假塑性流体特征,与原淀粉相比改性后的淀粉糊热稳定性和剪切稳定性得到提高。     

Changes in rheological properties of hydroxypropyl potato starch pastes during freeze—thaw treatments. III. Effect of cooking conditions and concentration of the starch paste

The effects of different cooking conditions and concentrations on the freeze-thaw stability of hydroxypropyl potato starch (molar substitution 0·125) paste were investigated by dynamic rheological measurements and syneresis determination. The cooking conditions of the starch were chosen by taking the starch pastes at peak consistency (SP/Peak), at half breakdown consistency (SP/HB), after being held at 95°C for 15 min (SP/95°C) and after the whole pasting cycle (SP/25°C) in the Brabender Amylograph. The concentration effect was studied with the starch pastes after a whole pasting cycle at 35, 50 and 65 g kg^?1. Depending on cooking conditions and concentration, the rheological responses in changes of complex modulus (G*) and phase angle () of the starch pastes, with regard to the number of freeze-thaw cycles, differed considerably. This indicated that the starch pastes had undergone various structural changes during freeze-thaw treatments. With an increased extent of pasting, and with an increased starch concentration, the rheological responses indicative of the destabilisation process of the starch pastes were, in general, delayed. The number of freeze-thaw cycles required for the appearance of a peak in G*, related to the first syneresis, was one, two, five and six for SP/Peak, SP/HB, SP/95°C and SP/25°C, respectively. For the starch pastes at 35, 50 and 65 g kg^?1, it was four, six and seven cycles, respectively. Based on these rheological data, it was suggested that the amount of inter-mingled amylose and amylopectin in the dispersion of hydroxypropyl starch paste is the main controlling factor, which plays a critical role in the rheological response as well as in the syneresis.     

Potential of Amaranthus cruentus BRS Alegria in the production of flour,starch and protein concentrate: chemical,thermal and rheological characterization

BACKGROUND: Amaranth is a little‐known culture in Brazilian agriculture. Amaranthus cruentus BRS Alegria was the first cultivar recommended by Embrapa for the soil of the Brazilian scrubland. In order to evaluate the potential of this species in the production of flour, starch and protein concentrates, the latter products were obtained from A. cruentus BRS Alegria seeds, characterized and compared with the products obtained from the A. caudatus species cultivated in its soil of origin. RESULTS: The seeds of A. cruentus BRS Alegria furnished high‐purity starch and flour with significant content of starch, proteins, and lipids. The starch and flour of this species presented higher gelatinization temperatures and formed stronger gels upon cooling compared with those obtained from the A. caudatus species. This is due to their greater amylose content and a difference in the composition of the more important fatty acids, such as stearic, oleic and linoleic acids, which indicates that they have greater heat stability. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis and differential scanning calorimetry revealed the presence of albumins, globulins, glutelins and prolamins in the protein concentrate, which was obtained as a byproduct of starch production. CONCLUSION: Amaranthus cruentus BRS Alegria has potential application in the production of flour, starch and protein concentrates, with interesting characteristics for use as food ingredients. Copyright © 2010 Society of Chemical Industry     

菊糖对马铃薯淀粉糊流变特性及体外消化的影响

为了研究菊糖对马铃薯淀粉糊流变特性及体外消化的影响,以马铃薯淀粉为原料,通过流变仪测试和体外酶解等方法测定菊糖-马铃薯淀粉共混体系的特性变化。流变仪测试结果表明:在试验的菊糖添加量范围内,菊糖-马铃薯淀粉共混糊的流变学特性均符合幂率模型,为假塑性流体;菊糖的添加在一定程度上降低了淀粉糊黏度,且随着添加量的增加,这一趋势加大。体外酶解结果表明:菊糖可以在一定程度上抑制马铃薯淀粉的水解速度及程度,且随着菊糖添加量的增加其抑制程度也相应增加;水解指数HI及预测血糖值e GI均随着菊糖添加量的增加而逐渐降低;在菊糖最大添加量时(菊糖与淀粉配比为1∶5),菊糖-淀粉共混体系的水解率、HI和e GI值分别由原淀粉的70%、57.87和71.48降至50%、42.74和63.17。研究结果提示适量的菊糖不仅可以改善马铃薯淀粉糊的流变性能,还可以降低其血糖指数。     

Thermal,rheological, and mechanical properties of normal corn and potato starch blends

Native corn and potato starches were mixed in different proportions. Blends presented similar values to potato starch at onset temperature and at ending temperature to corn starch. CS20PS80 blend had the highest values for hardness between blends due to the formation of a three-dimensional network with corn starch granules that act as composite material. Some blends exhibited higher recovery viscosity than native starches, possibly due to interactions. Gelatinization temperature, swelling power, phosphorous content, granule size, and x-ray pattern played an important role in the resulting properties, however, the amylose content did not show influence due to both starches having a similar content.     

Pasting,rheological properties and gelatinization kinetics of tapioca starch with sucrose or glucose

Effects of sugars (sucrose and glucose) on the pasting, rheological and thermal properties of tapioca starch (TS) were studied. Rapid visco-analyser (RVA) and differential scanning calorimetry (DSC) showed that pasting and gelatinization temperature of TS increased with increased sugar concentration in the order of sucrose > glucose. Peak, breakdown, final and setback viscosities tended to increase with increased sugar content. Rheological parameters calculated from Herschley–Bulkley model showed sugar addition increased the yield stress and consistency coefficient, while decreased the thixotropy of TS gels. Loss tangent determined from dynamic viscoelastic tests revealed that sugars increased the solid-like characteristics of TS gels. Kinetics analysis showed E_a raised and rate constants declined in the presence of sugars, suggesting the same sugar effect as the experiments of RVA and DSC. And thus kinetics analysis could provide new evidences for the influence of sugars on starch gelatinization.     

Prediction of the rheological properties of wheat dough by starch-gluten model dough systems: effect of gluten fraction and starch variety

The present study sought to investigate the rheological properties of wheat starch-gluten (WS-G) and potato starch-gluten (PS-G) model doughs with different gluten fractions to elucidate the effectiveness of using model dough to predict wheat dough properties. The highest linear viscoelastic region, frequency dependence, maximum creep compliance and the lowest viscoelastic modulus and zero shear viscosity were observed in the wheat dough, followed by WS-G and PS-G model doughs. PS exerted a more significant damage effect on the gluten network while WS shared a tight integration with gluten protein, forming a more stable dough structure. The viscoelasticity of the model doughs shared a close association with the wheat dough under increased gluten fraction, while the frequency dependence of the model doughs showed no trend towards wheat dough. Therefore, starch-gluten model dough could not fully stimulate the functionality of wheat dough irrespective of its gluten fraction.     

淀粉溶胶流变特性及应用研究进展

综述了改性前后淀粉溶胶流变特性,以及淀粉溶胶流变特性的应用。指出淀粉溶胶的流变特性主要为非牛顿流体的假塑性流体,且受诸多因素的影响;淀粉经过改性后,流动性有较大的改善;人们开拓了淀粉在塑料、包装材料、食品、黏合剂等方面的应用;淀粉的流变特性在工业和农业方面有着广阔的应用前景和市场前景。     

玉米淀粉糊流变特性研究

利用AR–500流变仪,研究了不同质量浓度、温度和加热时间条件下玉米淀粉糊的流变特性。结果表明:玉米淀粉糊主要表现为假塑性非牛顿流体,流变特性服从Carreau模型。在同一剪切速率下,黏度随着质量浓度增大而增大,随着温度升高而降低,随着加热时间延长而下降;在同一质量分数条件下,黏度随着剪切速率的增加而呈现先增加后降低的趋势;在同一温度条件下,黏度随着剪切速率的增加而降低。     

Gel texture and rheological properties of normal amylose and waxy potato starch blends with rice starches differing in amylose content

This study characterised the textural and rheological behaviour of blends of rice (waxy, low- and high-amylose) and potato (waxy and normal) starch. Blends of potato starch with rice starch in the ratios of 100:0, 80:20, 60:40, 40:60, 20:80 and 0:100 were tested. Addition of rice starch (except high-amylose rice starch) greatly increased the swelling of rice–potato starch mixtures. Addition of rice starch decreased gel firmness for most starch mixtures and increased gel adhesiveness for blends containing waxy potato starch. For rheological measurements, storage modulus was much higher than loss modulus of blends, indicating solid-like behaviour. Starch blends with 20%/40% proportion of rice starch showed a greater thickening effect, whereas with further increase in rice starch proportion, a pseudoplastic, shear-thinning behaviour was observed. This study may provide a basis to develop blends of potato and rice starch for potato noodle production without use of chemical additives.     

Effect of damaged starch on the rheological properties of wheat starch suspensions

The influence of damaged starch content on particle size distribution and rheological properties of unheated starch suspensions and pasting properties were investigated. Four samples containing different amounts of damaged starch were studied. Particle size distribution curves shifted toward higher diameters, and a greater overlap of both populations of particles (A- and B-type granules) and a decrease of both peak heights were produced. The flow curves of unheated starch suspensions were fitted using the power law model. The flow behavior indexes were higher than the unit. The consistency coefficient increased with the increment of damaged starch content. Unheated starch suspensions showed time-dependent rheological behavior and were described by the Weltman model. The unheated suspensions exhibited a thixotropic behavior. With regard to the pasting process, the increment of damaged starch content produced gradual reductions in peak viscosity, final paste viscosity, breakdown and setback. Results demonstrated the importance of the presence of physically damaged granules in wheat starch rheological characteristics.     

食品添加剂对大米淀粉流变特性的影响

采用动态流变仪对米线生产中三种常用添加剂焦磷酸钠、单甘酯和淀粉醋酸酯对大米淀粉流变特性的影响进行了研究。研究结果表明：适当添加焦磷酸钠可以通过糊化时抑制淀粉颗粒的崩溃解体来提高大米淀粉凝胶体系的强度；添加单甘酯由于单甘酯与直链淀粉形成了络合物，因而大米淀粉凝胶强度显著降低；淀粉醋酸酯的添加可以适度降低大米淀粉凝胶的强度，提高淀粉凝胶的柔韧性。     

Thermal characteristics of ohmically heated rice starch and rice flours

ABSTRACT:  Thermal properties of conventionally and ohmically heated rice starch and rice flours at various frequencies and voltages were studied. There was an increase in gelatinization temperature for conventionally heated rice starches since they were pregelatinized and became more rigid due to starch–chain interactions. In addition, there was a decrease in enthalpy (energy needed) for conventionally and ohmically heated starches during gelatinization; thus, the samples required less energy for gelatinization during DSC analysis. Ohmically heated commercial starch showed the greatest decrease in enthalpy probably because of the greatest extent of pregelatinization through ohmic heating. Brown rice flour showed the greatest gelatinization temperature resulting from the delay of starch granule swelling by lipid and protein. Enthalpy of ohmically heated starches at 20 V/cm was the lowest, which was most likely due to the lower voltage resulting in a more complete pregelatinization from a longer heating time required to reach 100 °C. Ohmic treatment at 70 V/cm decreased onset gelatinization temperature of white flour; therefore, it produced rice flour that swelled faster, whereas the conventionally heated sample showed a better thermal resistance.