Physicochemical and functional properties of Caryota urens flour as compared to wheat flour

Starch digestibility, thermal, pasting and gelling properties of Caryota urens (CU) flour were investigated using wheat flour as reference. Amylose content of CU and wheat flour was 32.1% and 28.3%, respectively. CU flour had very low content of protein and lipid but had a high content of total starch (98.2%) and resistant starch (RS) [42.5%]. Gelatinisation temperature (78.5 °C) of CU flour was higher than wheat flour. Pasting behaviour of CU flour was similar to that of high swelling tuber and root and waxy starches. CU flour retrograded to a greater extent than wheat flour. Very specific gelling behaviour was noticed for CU flour where it produced significantly harder gel with high paste clarity, fracture ability, adhesiveness, gumminess and chewiness. Expected glycaemic index (eGI) of CU and wheat flour was 92.4 and 100.4, respectively. CU flour had high eGI despite high content of resistant starch.     

Rheological properties of wheat flour and quality characteristics of pan bread as modified by partial additions of wheat bran or whole grain wheat flour

The use of bran and whole grain flour changes dough rheology and causes difficulties in manufacturing bakery products. The aim of this study was to analyse the influence of substituting refined wheat flour (WF) by wheat bran (WB; 5%, 10%, 20%, 30% and 40%) or whole grain wheat flour (WGWF; 10%, 20%, 30%, 40% and 50%) on dough rheological properties and pan bread quality characteristics. The addition of WB and WGWF increased water absorption and resistance to extension and decreased stability, extensibility and peak viscosity. Effects with WB were more pronounced. The presence of WB or WGWF increased crumb moisture content, firmness and hardness and decreased specific volume of pan bread. It is important to set new farinographic and extensographic standards when using WB and WGWF, allowing for a correct correlation between rheology and quality characteristics of bakery products, as the same standards used for WF are not valid.     

Antioxidant potential of wheat flour chapattis as affected by incorporating barley flour

Whole wheat flour was replaced with whole barley flour at levels of 28, 56 and 84 g/100 g to prepare chapattis and their antioxidant properties were evaluated before and after baking. The total phenolic content (TPC) in wheat flour was 2062 μg ferulic acid equivalents/g, total flavonoid content (TFC) was 966 μg catechin equivalents/g and antioxidant activity was 12.3% and they increased by 57.1, 101 and 22.6%, respectively upon incorporating barley flour at the highest level. Baking significantly decreased the TPC by up to 17.0% and TFC by up to 30.7% however the AOA increased by 13%. Barley flour incorporation significantly increased the reducing power which upon baking showed an insignificant decrease. Polyphenol oxidase (PPO) activity significantly increased by up to 109% upon incorporating barley flour however baking lowered PPO activity by 67.9%. Chapattis containing barley flour can be used to deliver the bioactive components of barley.     

Comparative properties of cakes prepared from rice flour and wheat flour

Received: 20 September 1999     

The formation and properties of wheat flour doughs

Among the cereal flours, only wheat flour will form a viscoelastic dough when mixed with water. The viscoelasticity appears to be because the gluten proteins are water compatible and thus will swell and interact. The gluten protein's large molecular size and low charge density appear to allow them to interact by both hydrogen and hydrophobic bonds. Wheat flour doughs are also unique in their ability to retain gas. This property appears to result from a slow rate of gas diffusion in the dough. The third major unique property of wheat flour doughs is their ability to set in the oven during baking, and thereby to produce a rigid loaf of bread. Although not clearly understood, this appears to be a heat-induced crosslinking of the gluten proteins.     

出粉率对小麦粉理化特性及面条品质的影响

从制粉生产线上取82种系统粉,并根据灰分含量和流量配制出粉率为55％、60％、65％、70％、75％、80％、88％、95％、100％等9种不同小麦粉.对不同出粉率小麦粉理化特性及面条品质进行研究,结果表明:出粉率为55％～70％时,小麦粉来源于胚乳,小麦粉理化特性及面条品质较好,且各类指标在较小范围内浮动;出粉率为7...     

谷氨酰胺转胺酶对大豆粉-面粉面团特性的影响

目的:探讨TG对大豆粉-面粉面团加工特性的影响,通过TG的应用提高大豆粉在面制品中的添加量;方法:采用粉质仪、拉伸仪、流变仪测定不同比例大豆粉(7.5%,10%,12.5%,15%,17.5%)的中筋粉或高筋粉面团在添加0.5%TG和不添加TG的情况下搅拌特性、拉伸特性和动态流变学特性;结果:添加0.5%的TG可改善大豆粉和小麦粉面团的流变特性和超微结构,增加面团筋力;结论:添加TG可使面粉中大豆粉的添加量达12.5%～15%.     

Particle size,rheological and structural properties of whole wheat flour doughs as treated by high pressure

Effect of high-pressure treatment (300–600 MPa) and flour-to-water ratio (1:1, 1:2, 1:3, and 1:4) on functional, rheological, thermal, and structural properties of whole wheat flour dough were investigated. The particle size distribution, especially Dv90 (90% of the volume distribution), was significantly reduced by the pressure treatment. The damaged starch content increased significantly with the applied pressure and water content. The damaged starch absorbed more water, and subsequently increased the water holding capacity. Thermal transitions and mechanical property of pressure-treated samples were measured by differential scanning calorimetry, and rheometry, respectively. The peak viscosity, hot paste viscosity, and final viscosity decreased significantly with increasing pressure intensity. Hardness increased with the increasing pressure level while stickiness decreased at similar conditions. Fourier-transform infrared spectroscopy showed changes in the amide I region of the wheat protein. The sodium dodecyl sulfate polyacrylamide gel electrophoresis further indicated changes in the protein subunits that occurred after pressurization.     

配麦和配粉对小麦粉面团流变学特性的影响

选用7种高、中、低筋小麦,对其品质进行综合分析;根据分析结果以水饺粉为目标粉进行配麦和配粉实验,对混合粉的流变学特性进行分析研究。结果表明差异性大的小麦(粉)以合适的比例搭配能明显改善混配粉的流变学特性。配麦和配粉在提高稳定时间,降低弱化度,改善拉伸特性方面区别并不明显,但在降低吸水率和拉伸度方面配粉比配麦表现效果更加明显。     

Thermal and dynamic rheological properties of wheat flour fractions

A commercial high gluten flour (HGF) was fractionated into prime starch (PS), tailing starch (TS), and gluten (G). Fractions were examined alone or in various combinations. Dynamic rheological properties of samples were measured in an oscillatory rheometer (strain 0.02; frequency 0.1 Hz) during heating at 1°C/min. Thermal characteristics of samples were determined by differential scanning calorimetry (DSC) at a heating rate of 10°C/min. The loss (G″) and storage (G′) moduli of PS and mixed G/PS, G/TS, and G/PS/TS increased after 60°C, reaching peak values (e.g. 81, 301, 313, and 3000 Pa in G′, respectively) around 75°C after which the moduli decreased. HGF showed a steady increase in G′ from 32 to 2490 Pa as temperature increased from 65 to 90°C, indicating continuous formation of elastic networks. Cooling increased G′ for G/PS/TS, decreased G′ for HGF, and produced no rheological transitions for all samples. TS and G alone did not exhibit appreciable viscoelastic responses to the heating and cooling temperatures. DSC measurements revealed a major endothermic transition in HGF. This transition, with a peak around 60°C, was due to starch gelatinization. The presence of G or TS resulted in reduced melting enthalpies of starch in the PS fraction. Gluten or TS fractions alone or in combination did not exhibit any endothermic transitions.     

基于主成分小米-小麦混合粉面团流变学特性综合评价

选择13个品种小米粉按照0~35%比例与小麦粉混合,通过对小米-小麦混合粉面团粉质特性和拉伸特性分析,基于主成分建立了混合粉面团流变学特性综合评价模型。结果表明,随着小米粉添加比例的增加,小米-小麦混合粉面团综合主成分值逐渐下降;主成分分析提取2个主成分,累计方差贡献率为85.21%;综合主成分值越高,小米-小麦混合粉面团流变学特性越好。豫谷18、白谷、冀谷19适宜制作高筋粉类食品;112和113综合主成分值最低,流变学特性较差,较适宜制作低筋类食品;当小米粉添加量超过15%时,除白谷、豫谷18这两个品种之外,其余品种综合主成分值均为负值,小米-小麦混合粉面团品质显著降低。     

小麦面粉蛋白质特性和面团流变学特性的关系

目的探究小麦面粉蛋白质理化特性与面团流变学特性之间的关系。方法以19份抗旱节水鉴定品种小麦籽粒为试验材料,测定了蛋白质、湿面筋、谷蛋白大聚体含量、沉降指数等面粉蛋白质理化特性,以及粉质参数和拉伸参数等面团流变学特性,采用通径分析研究了面粉蛋白质理化特性与面团流变学特性的关系。结果面粉蛋白质含量对面团吸水率直接增强效应较大,但对稳定时间、拉伸长度的抑制效应较大;谷蛋白大聚体含量对形成时间、最大拉伸阻力、拉伸面积的直接增强效应和综合增强效应均较大;沉降指数对稳定时间和最大拉伸阻力、拉伸面积的直接增强和综合增强效应较大;所测蛋白质理化特性中未发现对拉伸长度有增强效应的指标。结论面粉中谷蛋白大聚体含量和沉降指数是对面团形成时间、稳定时间、拉伸阻力影响较大的因素,影响为正效应,可为专用面粉生产质量控制提供参考。     

Rheological and baking properties of cowpea and wheat flour blends

Effect of blending 50 to 250 g kg⁻¹ cowpea flour in wheat flour on rheological, baking and sensory characteristics of bread, chapati, cookies and muffins was studied. Farinograph water absorption, dough development time, mixing tolerance index and dough stability increased significantly with increased amount of cowpea flour. Incorporation of cowpea flour lowered gelatinisation time and peak viscosity. Loaf volume and overall acceptability scores of bread were reduced significantly beyond 150 g kg⁻¹ incorporation of cowpea flour. There were significant changes in specific volume and overall acceptability scores of muffins, registering an initial improvement up to 50 g kg⁻¹ and a significant decline thereafter. © 1999 Society of Chemical Industry     

Rheological properties of wheat flour substitutes/alternative crops assessed by Mixolab

Wheat is one of the most common cereals used in the world. However, due to greater public awareness of celiac disease and gluten intolerance as well as consumers demands for healthy food and variety in food products, in many widely consumed staples, such as bread, wheat flour is fully or partially replaced with flour from other cereals, pseudocereals or legumes. Although wheat flour alternatives are readily available in the market, these products are often of inferior quality. The aim of this paper was to predict the suitability of alternative crops such as rice, corn, buckwheat, amaranth and soya for the production of quality bread. Their rheological properties were studied, and compared to the properties of wheat flour which served as a benchmark. The tested alternative cereals, pseudocereals and legumes were selected in order to represent the widely used ones in gluten-free products as well as the ones found to be nutritionally improved according to recent publications. Moreover, the differences between wheat and buckwheat flour, and their wholegrain counterparts were also studied. The determination of rheological properties of wheat flour dough as well as the dough from other raw materials (rice, corn, buckwheat, amaranth and soya) was performed by Mixolab. According to results obtained by Mixolab measurements, flours from different raw materials exhibited Mixolab profiles which greatly differ from wheat flour profile. Samples of rice and both types of buckwheat flour expressed the most similar rheological behaviour to wheat flour. However, since, there was no tested material which exactly mimic wheat flour dough properties, it was concluded that their mixtures would give the optimal rheological profile. Although it is a very challenging task to mimic wheat flour unique breadmaking properties, it is possible to create products having similar rheological behaviour to wheat flour dough, but improved functional properties.     

滴定法检测小麦粉中溴酸钾含量

利用溴酸钾在酸性溶液中与碘化钾反应析出碘,用硫代硫酸钠标准溶液滴定定量的原理,使用滴定法测定小麦粉中溴酸钾的含量,操作简便,最低检测限0.01 g/kg,回收率83%～107%,变异系数都在5%之内,方法准确可靠.