Impact of endogenous constituents from different flour milling streams on dough rheology and semi-sweet biscuit making potential by partial substitution of a commercial soft wheat flour

A flour fractionation-reconstitution procedure was used to study the substitution of a commercial soft wheat flour with gluten, water extractables, prime starch and starch tailing fractions isolated from patent and clear flour streams on dough rheology and semi-sweet biscuit characteristics. Substitution of soft wheat flour with increasing levels of the native patent and clear flour streams raised the dough consistency, hardness and elastic properties as well as the biscuit textural attributes (density, hardness). The dough stickiness of the base flour was also reduced and the biscuits were free of cracks. Gluten isolated from the patent flour had a greater impact on dough consistency, hardness and elastic properties than gluten obtained from the clear flour, likely due to the superior protein quality of the former. Additionally, with increasing gluten levels in the fortified flour there were moderate increases in biscuit density, hardness, and lower crunchiness. The addition of starch tailings produced the largest impact on consistency and hardness of the dough. This fraction also exerted a pronounced effect on biscuit density and hardness, while it lowered crunchiness, presumably due to its higher pentosan content. Overall, the dough rheological properties and biscuit characteristics were controlled by the amount-nature of the fractions added; i.e., besides gluten (amount and quality), other constituents such as pentosans and the overall composition of the flour blends can largely affect the quality of the semi-sweet biscuits.     

Effects of plasma-activated water and heat moisture treatment on the properties of wheat flour and dough

Plasma-activated water (PAW) production and use is an emerging technology for enhancing product safety, extending shelf-life and quality retention, and promoting sustainable processing. At present, it has generated considerable attention for applications to starch and flour modification. This work presents an innovative approach to wheat flour (WF) modification using PAW and heat-moisture treatment (HMT), and compares this approach with distilled water (DW) treatment. As expected, PAW and HMT promoted flour granule clustering, increasing particle size. These treatments accelerated molecular interactions between wheat starch and non-starch components (e.g. proteins and lipids), which eventually increased resistant starch (RS) content. Addition of modified flour (30 g) to WF positively affected its rheological properties, and closely bound water content of the dough. The gluten protein network structure in the dough suffered varying degrees of damage. In conclusion, our results showed that PAW and HMT may provide a novel beneficial method for modifying wheat flour during food processing to obtain viscoelastic wheat flour products with nutritional functions.     

添加辣木叶粉对小麦粉面团品质的影响

考察不同粒径辣木叶粉对小麦面团品质的影响。采用普通粉碎、超微粉碎技术制备不同粒径的辣木叶粉,采用分光测色计、粉质仪、拉伸仪、黏度仪分析辣木叶粉对小麦面团品质的影响。结果显示添加5%辣木叶粉后,小麦粉的吸水率、糊化温度没有显著变化;形成时间、稳定时间均显著下降;45 min醒发后的最大拉伸阻力由234.9 BU下降至130 BU左右,延伸度下降;峰值黏度由531 BU显著下降至303～355 BU,回生值亦下降,衰减值上升。结果表明添加辣木叶粉一定程度减弱了小麦面团的面筋强度和淀粉黏性,但减弱了小麦粉面团的回生,超微粉碎可以减弱辣木叶粉对小麦粉面团的负面影响,研究为辣木叶粉在面制品行业的应用提供了理论参考。     

高膳食纤维面团热机械学及面包的烘焙特性

研究大豆纤维粉(soybean dietary fibre,SDF)和玉米抗性淀粉(resistant starch,RS)及其混合物以20%、30%比例部分替代小麦粉在高膳食纤维面包中的应用,并分析高膳食纤维对面团热机械学特性及面包烘焙特性的影响。结果表明:SDF与RS的引入可提高面团持水性与吸水率(分别提高43.3%～63.3%和5%～7.6%),降低C5-C4值,对淀粉回生产生一定的抑制作用。两者对面团稳定时间和C1-C2的影响不同,RS会显著降低面团稳定时间(为对照组的53.52%～66.46%),增大C1-C2值24.14%～27.59%,蛋白质弱化度提高,而SDF对此则具有积极作用;通过对面包的烘焙特性分析发现,SDF与RS共用时具有协同作用,生产的面包不仅膳食纤维与蛋白质含量高,质构与风味较单独添加SDF有所改善,且提高了RS单独应用时的面包水分含量,提高得率。综合面包比容、色泽、质构与营养而言,5%SDF-15%RS和10%SDF-10%RS组制作的高膳食纤维面包品质最佳,且口感良好。     

Effect of soybean proteins on gluten depolymerization during mixing and resting

BACKGROUND: Gluten and soy proteins interact as a consequence of dough mixing; however, there is no evidence of the effect of soy protein on gluten depolymerization. The aim of this study was to assess the depolymerizing effect of soy protein on gluten network after mixing and resting of mixed doughs. Therefore, the changes in glutenin macropolymer (GMP) content, protein composition and free sulfhydryl content were evaluated. RESULTS: The protein profile from gluten–soybean blends, obtained by multistacking SDS‐PAGE, showed differences when compared to gluten profile. Soy and gluten proteins were extracted together with SDS buffer, which showed that soy proteins remained associated to insoluble wheat proteins even after hand‐washing the dough to obtain gluten. GMP content was determined to analyze the effect of soy protein on GMP gel formation. Protein content of GMP obtained from flour mixes and doughs was increased by inactive soy flour because soy proteins became insoluble and precipitated together with GMP. Active soy flour decreased GMP content due to gluten depolymerization. CONCLUSION: Soy proteins were associated to wheat protein through physical interaction and covalent and non‐covalent bonds during mixing and resting. These interactions produced large and medium‐size polymers. This fact increased SDS solubility of insoluble gluten proteins, producing a weakening of the gluten network. Physicochemical status of soy protein in the product had a great influence on how wheat–soy proteins interact. Copyright © 2007 Society of Chemical Industry     

添加糯小麦粉对小麦粉及其面条品质特性的影响

糯小麦与普通小麦的主要差异是糯小麦不含直链淀粉或其含量很低,其对面制品的制作品质产生一定的影响。本研究利用"济糯1号"分别与"济麦20"和"济麦22"按20%、40%、60%和80%的添加量进行配粉,研究糯小麦粉对普通小麦粉品质特性的影响及其面条制品品质的改良作用。结果表明:"济糯1号"的淀粉糊化回升值为449 c P,显著低于"济麦20"和"济麦22";籽粒硬度达64.89,籽粒蛋白质含量(干基)达16.14%,面筋指数为66.08%,粉质仪稳定时间为2.00 min,鲜面条色泽变化小,2 h和24 h的ΔE*分别为3.83和5.29;"济糯1号"与"济麦20"的配粉中,随糯小麦粉添加量的增加,配粉的淀粉回升值降低,面筋指数降低,吸水率增加,面团稳定时间变短,鲜面条色泽2 h和24 h的ΔE*逐渐变小,配粉面条的适口性和光滑性更好;"济糯1号"与"济麦22"的配粉中,随糯小麦粉添加量的增加,面粉蛋白含量增加、面筋指数升高、吸水率增加、淀粉糊化的回升值降低,鲜面条色泽2 h和24 h的ΔE*逐渐变小,配粉的面条制作品质好,面条的适口性和光滑性均改善;糯小麦粉的添加使配粉的面粉品质特性和淀粉特性更有利于面条制作品质的改良,"济糯1号"适宜添加量为20%~40%。     

核磁共振及其成像技术研究面粉吸水率及其形成过程

利用核磁共振及其成像技术研究了面筋含量、含水量、添加物、搅拌与面团中水的状态之间的关系。水分状态的测定使用自旋-晶格和自旋-自旋弛豫时间(T1和T2)。在面团搅拌过程中,在初期T2*和相应的质子密度值随着搅拌时间的延长而快速减小,说明自由水加入到面粉中后迅速与面粉中的蛋白以及其他成分发生了水合作用。T2*与搅拌时间的曲线体现了面团的这个搅拌过程,从中可以直观的得到面团的最佳搅拌时间。搅拌时间受水分含量的影响,并且不同面筋含量的面粉搅拌稳定时间也不相同。面筋含量与搅拌时间成才正比。高温有利于面团的形成,并且影响面团中水分的流动性。通过低、中、高三种不同面筋含量面粉吸水率与NMR自旋-晶格弛豫时间关系的研究,实验结果发现T1以及T1幅度随水分含量的增加而增加,随面筋含量的增加而减少,并且得到了T1与吸水量之间的关系曲线,不同面筋含量面粉的最佳吸水量:湿面筋含量25.4%面粉的吸水量为55.0%;湿面筋含量30.4%面粉的吸水量为57.5%;湿面筋含量35.8%面粉的吸水量为60%。     

Characterisation of flour, starch and fibre obtained from sweet potato (kumara) tubers, and their utilisation in biscuit production

Sweet potato (kumara) tubers of differing colours (orange, red and white) were used to produce tuber flour, a purified starch fraction and an isolated fibre extract. The fractions from each tuber colour were added into a biscuit mixture, and the effects of tuber source and fraction composition were observed in relation to the physico-chemical characteristics of biscuits. Addition of sweet potato flour and fibre fractions to white wheat flour significantly reduced the pasting properties (peak and final viscosity) of the resulting gels by up to seven-fold compared with the control wheat flour gel (as determined by the Rapid Visco Analyser). The addition of sweet potato starch affected the pasting properties of wheat flour–sweet potato starch mixes to a lesser extent. Biscuit texture (force required to cause a biscuit to fracture) was significantly reduced with the incorporation of sweet potato fibre into the biscuit dough preparation, this was linked to a reduction in biscuit thickness and spread ratio. However, the addition of sweet potato flour and starch resulted in biscuits of similar firmness as the control biscuits.     

蛋白质和淀粉对面团流变学特性和淀粉糊化特性的影响

以3个筋力不同的小麦粉为材料,利用分离重组方法,在保持小麦粉其他成分不变的情况下,组成不同面筋蛋白和淀粉含量的配粉,研究面筋蛋白和淀粉添加量对面团流变学特性和面粉糊化特性的影响。结果表明：随着面筋蛋白添加量的增加,3种筋力小麦粉配粉的面团稳定时间和粉质质量指数均呈升高趋势,峰值黏度、低谷黏度、最终黏度、稀懈值、回生值等总体呈下降趋势。小麦粉添加淀粉后,面团稳定时间和粉质质量指数均呈下降趋势,峰值黏度、低谷黏度、最终黏度、稀懈值、回生值等总体呈升高趋势。面筋蛋白和淀粉对小麦面团吸水率和面粉糊化温度的影响均较小。不同筋力小麦粉配粉各品质指标总体变化趋势一致,但变化幅度有一定差异。     

Dough rheology and baking performance of wheat flour–lupin protein isolate blends

The impact of addition of two lupin protein isolates (LPI), enriched either in proteins belonging to globulin (LPI G) or to albumin (LPI A) fraction, on wheat flour dough and bread characteristics was investigated. LPI addition increased the dough development time and stability plus the resistance to deformation and the extensibility of the dough. The presence of LPI proteins in dough affected bread quality in terms of volume, internal structure and texture, while extra gluten addition to the blends to compensate for wheat gluten dilution, resulting from LPI addition, led to an improvement of bread quality characteristics. Generally, the incorporation of LP isolates to wheat flour delayed bread firming. The results obtained are discussed in terms of a possible action of LPI particles as a filler of the gluten network and partly in terms of possible interactions that take place between the gluten protein constituents and those of lupin.     

粒径和面筋蛋白含量对面条中淀粉体外消化性的影响

为研究粒径和面筋蛋白含量对面条中淀粉体外消化性的影响,在不同粒径的小麦面粉中分别添加0%、5%和10%的面筋蛋白制作中式面条,烘干研磨后分离出大颗粒与小颗粒面条,研究面条样品的形貌特征、结构特性热力学特性和淀粉体外消化特性。结果表明,随着面条中面筋蛋白含量增加,面条表面的平滑度增强,糊化温度升高而焓值降低,且蒸煮后面条中形成的面筋网络面积增加。体外消化动力学结果显示随着面粉粒径的减小或面筋蛋白含量的增大,淀粉消化程度降低。     

Gluten–starch interface characteristics and wheat dough rheology—Insights from hybrid artificial systems

Referring to the total surface existing in wheat dough, gluten–starch interfaces are a major component. However, their impact on dough rheology is largely unclear. Common viewpoints, based on starch surface modifications or reconstitution experiments, failed to show unambiguous relations of interface characteristics and dough rheology. Observing hybrid artificial dough systems with defined particle surface functionalization gives a new perspective. Since surface functionalization standardizes particle–polymer interfaces, the impact on rheology becomes clearly transferable and thus, contributes to a better understanding of gluten–starch interfaces. Based on this perspective, the effect of particle/starch surface functionality is discussed in relation to the rheological properties of natural wheat dough and modified gluten–starch systems. A competitive relation of starch and gluten for intermolecular interactions with the network-forming polymer becomes apparent during network development by adsorption phenomena. This gluten–starch adhesiveness delays the beginning of non-linearity under large deformations, thus contributing to a high deformability of dough. Consequently, starch surface functionality affects the mechanical properties, starting from network formation and ending with the thermal fixation of structure.     

不同粒径小米粉对面团流变特性及馒头质构特性的影响

为研究小米粉添加对面团流变特性和馒头制品质构特性的影响,分别选取不同粒径的粳性和糯性小米粉,利用损伤淀粉测定仪、快速黏度分析仪等对不同小米粉的损伤淀粉含量和糊化特性进行分析,通过流变仪测定小米面团的流变学特性,结合扫描电镜观察小米面团微观结构变化,并利用质构仪测定小米馒头的质构特性。结果表明：随着小米粉粒径的减小,多数品种小米粉（除冀谷39和汇华金米）损伤淀粉的碘吸收率增加;受直支比的影响,相同目数下,粳性小米粉的峰值黏度、谷值黏度、最终黏度和回生值较糯性小米粉大。流变学研究表明,除汇华金米和冀谷39,储能模量与损耗模量随角频率增加总体上升。扫描电镜观察发现小米粉的添加使面团结构更加松散。小米粉的添加会对馒头质构性质中硬度、咀嚼性和弹性等有一定程度的负面影响。主成分分析表明馒头咀嚼性、损伤淀粉、峰值黏度、谷值黏度、最终黏度、崩解值和回生值可作为区分粳糯品种和馒头品质特征的指标。     

谷朊粉对糙米粉面团性质影响研究

研究了谷朊粉添加量对糙米粉面团性质的影响,主要包括粉质特性、热机械性质、流变学性质、微观结构等。结果表明:随着谷朊粉添加量增大,面团的吸水率、形成时间、稳定时间、淀粉衰减值和回生程度均在逐渐增长,蛋白弱化度在逐渐降低。糙米粉面团的弹性模量和粘性模量均在增大,且弹性模量大于粘性模量。扫描电镜结果显示:随着谷朊粉添加量增大,面团的网络结构越来越明显,淀粉颗粒镶嵌在蛋白形成的网络结构中,增加了面团的弹性及变形的阻力。     

Effects of size of cellulose granules on dough rheology, microscopy, and breadmaking properties

ABSTRACT:  Breadmaking was performed with cellulose-blended wheat flour. Cellulose granules (7 types) of various sizes (diameter) were prepared by kneading. With increase of the blend percent of the cellulose samples from 10% to 20%, breadmaking properties such as bread height and specific volume (SV) gradually decreased in every sample; however, the decreasing levels of the properties in 7 types of various sizes varied. The decrease of bread height and SV was associated with the size of the cellulose granule. It was observed at both 10% and 20% blends that the same bread height and SV as for bread baked with only wheat flour could be obtained when the diameter of cellulose granule was above 154 μm in cellulose/wheat flour breadmaking, while they gradually decreased with granules below 154 μm. When the largest cellulose granules were mechanically ground to make smaller ones, the bread height and SV decreased with increasing grinding time. It was ascertained that the size of the cellulose granule was important for breadmaking properties. Cellulose-blended wheat flour was subjected to mixograph tests. When cellulose granules above 154-μm dia were blended with wheat flour, the profile of the mixogram was almost the same as that for wheat flour; that is, the profile had a short mixing requirement and showed a viscous gluten matrix. However, when cellulose granules below 81-μm dia were blended, a different curve showing a nonviscous dough due to breakdown of the gluten protein was observed, as ascertained by microscopy. Farmograph test showed that the amount of the released gas from cellulose-blended bread dough increased with decrease of the size of the cellulose granule due to breakdown of the gluten protein.     

The Interplay Between the Main Flour Constituents in the Rheological Behaviour of Wheat Flour Dough

There is still considerable debate in the literature about the respective roles of starch and gluten in both the linear and non-linear rheology of wheat flour dough. Hence, to elucidate the individual contributions of gluten and starch to the overall dough behaviour, the rheological properties of dough and mixtures of different gluten-starch ratios were studied systematically in shear and extension, by means of an adequate rheological toolbox consisting of linear small amplitude oscillatory shear tests and non-linear tests such as creep-recovery in shear and uniaxial extension. The starch component plays a pivotal role in linear dough rheology. With increasing starch content, the linearity limit observed in oscillatory shear tests decreases as a power-law function. Starch also clearly affects the extensional viscosity at small strains. Consequently, in the linear region differences between different gluten systems may become obscured by the presence of starch. As breadmaking qualities are known to be intrinsically linked to the gluten network, it is imperative to probe the non-linear behaviour of dough in order to expose differences in flour quality. The quality differences between a strong and a weak flour type were revealed most clearly in the value of the strain-hardening index in uniaxial extension and the total recovery compliance in non-linear creep-recovery tests. Notwithstanding its earlier successful application to pure gluten gels, the accuracy of the critical gel model in predicting the linear rheological properties of dough was found to be limited, due to dough having a small linearity limit and a finite longest relaxation time.     

Separation of bread wheat flours into starch and gluten fractions: effect of water temperature alone or in combination with water to flour ratio

Two different commercial bread wheat flours (BF‐I, 65% extraction and BF‐V, 86% extraction) were separated into gluten and starch milk by making a dough, allowing some time for maturation, dispersing the dough in water and wet sieving/washing. The effect of using of warm water (20–45 °C) for dough making and washing on separation was studied for BF‐I flour at 640 g kg^?1 water to flour ratio of and 300 s maturation time, and the separation was found to improve with increase in temperature. The combined effects of water temperature (20–50 °C) and water to flour ratio (640–780 g kg^?1 for BF‐I and 620–870 g kg^?1 for BF‐V) were studied at 600 s maturation time. The quantities and dry matter contents of the gluten fraction and starch milk were measured; a sample of starch milk was centrifuged to obtain decantate, tailing and prime starch fractions, and the dry matter contents of each were determined. All the dried samples were also analysed for protein content, and the fractional recoveries of dry matter and protein in the gluten fraction, prime starch, tailings and decantate were calculated. The results indicated the optimum point for BF‐I flour to be the combination of optimum farinograph water absorption and 40 °C. BF‐V showed very poor separation behaviour within the ranges studied. At the optimum farinograph water absorption the use of warm water for dough making and 20 °C water for washing steps was also tried, but no significant improvement over the 20 °C results was obtained. © 2002 Society of Chemical Industry     

Physicochemical properties of hull-less barley fibre-rich fractions varying in particle size and their potential as functional ingredients in two-layer flat bread

The performance of barley fibre-rich fractions (FRF), as high dietary fibre ingredients, in two-layer flat bread was investigated. In addition, the effects of particle size reduction by pin milling on functional properties of FRF were studied. FRF enriched in non-starch polysaccharides (β-glucans and arabinoxylans) were obtained by roller milling of hull-less barley. Pin milling (PM) of FRF significantly reduced their particle size, slightly increased the solubility of β-glucans and arabinoxylans, and increased the viscosity of water slurries containing FRF. The addition of 20% of barley FRF to wheat flour significantly increased dough water absorption and weakened the dough properties, as indicated by farinograph mixing curves, but the FRF-enriched doughs exhibited good handling characteristics at the dividing and sheeting stages. The appearance, diameter, layer separation, crumb, and aroma of the FRF-enriched flat breads were comparable to that of the control. The PM of FRF did not significantly affect the dough handling or the quality characteristics of flat breads. The addition of 20% of barley FRF to wheat flour flat bread provided substantial health benefits by significantly increasing the total and soluble dietary fibre contents and by decreasing starch digestibility.     

Dynamic rheology of wheat flour dough. I. Non‐linear viscoelastic behaviour

Controlled stress rheometry was used to investigate the effects of starch and gluten fractions on the non‐linearity of wheat flour dough. Flour–water dough showed non‐linear viscoelastic behaviour over all stress values in a cyclic stress sweep. The amplitude‐dependent behaviour of the starch and amplitude‐independent nature of the gluten revealed that starch is responsible for the non‐linearity of the flour–water dough system. Adding starch to gluten caused a substantial narrowing of its linear viscoelastic range. © 2002 Society of Chemical Industry     

小麦粉吸水速率与其蛋白组成特性的关系

蛋白质理化特性的差异会导致小麦粉吸水速率的不同。本文以不同吸水速率的小麦粉为研究对象,测定面粉中粗蛋白含量、面筋蛋白含量、湿面筋含量、面筋指数、沉降值、谷蛋白溶胀指数、氨基酸含量及观测面团内部微观网络结构。结果表明,当粗蛋白含量13.25%降低到6.98%时,小麦粉的吸水速率从0.17 g/s增大到3.87 g/s;当麦醇溶蛋白含量从4.02%下降到1.53%及麦谷蛋白含量从5.28%下降到2.77%时,因形成的面筋膜的质量下降使小麦粉的吸水速率增大。同时吸水速率随湿面筋含量的减小而显著性增大,面筋指数对吸水速率无显著性影响。沉降值从69.50m L降到32.50 mL,谷蛋白溶胀指数从5.24%下降到3.33%,均与吸水速率呈显著性负相关(p0.05)。半胱氨酸含量从0.14%降低到0.04%,导致二硫键含量下降,使蛋白质间的分子作用力下降。当面团内部面筋网络结构紧密时,面粉成团时的阻力越大,其吸水速率越小。本研究表明蛋白质性质与小麦粉吸水速率呈负相关。