CLSM study of layers in laminated dough: Roll out of layers and elastic recoil

It has been thought that all fat and dough layers in laminated dough had the same thickness at the end of lamination. Moreover dough rheology (taking into account elastic recoil) is too complex to generalize calculation of the final thickness of the dough after lamination. Confocal laser scanning microscopy can differentiate the fat from the dough when combined with fluorophore staining (Nile Red and Alexa), and an algorithm was applied to quantify their respective thicknesses. When fat consistency was close to that of dough, the median thickness of fat was fairly close to theoretical values. Successive sheeting steps resulted in homogenization of layer thicknesses. The surface area of fat in relation to paste was greater than expected, especially for low numbers of sheeting steps, and also for samples with higher numbers of sheeting steps, presenting an exceptionally thick layer of fat (including that produced by back flow). Elastic recoil was between 20 and 90% higher than the targeted roll out; no significant effect of a harder fat consistency was found. Elastic recoil was less when the amount of fat in the sample was greater.     

六个强筋小麦品种不同出粉点面粉和面片的色泽及其褐变特点

为研究不同出粉点面粉面条色泽品质的差异,测定了6个强筋小麦品种通过布勒实验磨制粉获得的不同出粉点面粉的品质特性与面片色泽及褐变情况。结果表明,3道心磨和3道皮磨的面粉和面片色泽的L^*值均随出粉点后移呈下降趋势,而a^*值和b^*值则呈上升趋势;在面片放置过程中,3道心磨和3道皮磨面粉所加工面片色泽亮度的下降值、偏红度的上升值和偏黄度的上升值均随出粉点后移呈加速趋势。面片色泽与蛋白质含量、灰分含量和面粉L^*值关系密切。鲜面片放置24 h后色泽亮度的下降值与面粉粗蛋白质含量和灰分含量均呈极显著正相关,相关系数分别为0.444和0.758,而与面粉L^*值呈极显著负相关,相关系数为-0.681;色泽偏红度的上升值与面粉灰分和破损淀粉含量均呈极显著正相关,相关系数分别为0.834和0.760;色泽偏黄度的上升值与所有指标的相关均不显著。3心粉的色泽差,其所加工的面片色泽也较差,且色泽不稳定,在面片放置过程中色泽的亮度、偏红度和偏黄度保持性最差,褐变程度严重;1心粉的色泽好,其所加工的面色泽好,并在面片放置过程中,色泽的亮度和偏红度保持性较好,而色泽的偏黄度不如1皮粉和2皮粉的稳定。     

小麦面粉及鲜面片色泽的影响因素

为明确小麦面粉及鲜面片色泽的影响因素,选取10个江苏沿淮及淮南地区大面积推广小麦品种进行2年3点种植,比较不同品种、不同地点和不同年份面粉及鲜面片色泽差异并分析其影响因素,探讨面粉及鲜面片色泽与品质性状间的相关性。结果表明,扬麦11、扬辐麦4号和宁麦14的面粉及鲜面片色泽较好,亮度高、黄度低。基因型是决定面粉白度、亮度(L~*值)和黄度(b~*值)的主要因素;环境因素亦影响面粉及鲜面片色泽。扬麦16、宁麦14和郑麦9023在不同年度及不同地点的色泽表现稳定。面粉与鲜面片放置24h内的色泽间呈显著正相关;面粉白度与籽粒硬度和出粉率呈极显著负相关;面粉及鲜面片L~*值与蛋白质含量、湿面筋含量、揉混仪参数和粉质仪参数呈显著或极显著负相关,与糊化特性参数呈显著或极显著正相关。综上所述,面粉色泽主要由基因型决定,鲜面片色泽与面粉色泽显著相关,二者与籽粒品质具有显著相关性。在小麦育种中,可通过面粉色泽指标筛选高白度及品质的品种。     

中国面条的标准化实验室制作与评价方法研究

标准化的实验室制作与评价方法是面条品质改良的前提和基础.针对原商业部SB/T10137-93面条制作与品尝评分标准存在的不完善之处,对面条制作过程中的适宜加水量、和面时间、压片和煮面方法进行了研究,制定出我国面条的标准化实验室制作方法与评价系统.具体程序如下:以加水后面团水分含量为35.0%来确定最适宜加水量;通过低速(1 min)、快速(2 min)、低速(2 min)三个搅拌过程完成和面;在压面机上压片八次,并在最后一次压片时切成面条;在等量(2 L)水中用相同时间(6 min)煮等量(150 g)面条,煮面结束立即把面条放入冰水中冷却2 min.改进后的评价系统为色泽15分、外观10分、软硬度20分、粘弹性30分、光滑性15分、食味10分;以雪花粉为对照,将待评样品与对照相比后给出适宜分值.实验结果表明,改进的方法优于SB/T10137-93标准.     

Extensograph curve profile model used for characterising the impact of dietary fibre on wheat dough

A seven-parameter regression model was developed to determine changes in the shape of the Brabender extensograph curve as a result of supplementation of wheat dough with carob fibre and oat wholemeal. The shape of the curve, close to an inverted parabola, was well described by a cubic polynomial function. The exceptions were the initial and final sections of the curve, for the representation of which two exponential functions were used. Under the effect of the fibre-rich additions, the strongest variation was observed in the polynomial function parameters describing the slope and deflection of parabolic arms of the extensograph curve and the position of its peak, while the parameters showing the final course of the curve were subject to only slight changes. The reactivity of the additions during dough proving had a much stronger effect on the model parameters than on the variation of the maximum resistance and extensibility of the dough. The results indicate that the proposed model can be a useful tool for improving the analysis of extensional behaviour of bread dough.     

Development of an inline measurement technique to assess the quality of wheat dough during the sheeting process

Dough sheeting is an important processing operation in the production of various bakery products. The surface cracks on laminated wheat dough are undesirable and generally affect the final quality of the baked products. Although approaches exist for crack detection in the food industry, there is still a need to transfer and adapt it to the desired application especially with respect to inline measurement in the baking field such as dough sheeting. Therefore, the objective of the proposed methodology is to design and develop an inline measurement technique capable of automatic detection and evaluation of the dough surface as well as its measurement in terms of crack ratio. By adapting this technique, different types of dough were tested for their sensitivity to different rolling steps which in turn provides the initial rolling behavior inferences of different dough varieties. The proposed algorithm for the detection of surface cracks is evaluated with various performance measures.Industrial relevanceThe work described in this research is a novel and innovative approach that offers to benefit manufacturers of sheeting equipment in the improvement of equipment design. The bakers owning small and medium-sized enterprises are specially privileged from the successful application of this study, because their competitive capability increases due to the possibility of cost reduction.     

小麦面粉和鲜面片色泽及 Psy-A1 与 Ppo-A1 等位变异检测

为研究小麦面粉和鲜面片色泽及其与两个色泽相关基因等位变异之间的关系,以我国主要麦区17个大面积推广品种及1个优异品系为材料,进行面粉和鲜面片色泽分析和 Psy-A1 、 Ppo-A1 基因等位变异检测。结果表明,扬麦18、泛麦5号、扬麦9号、平安7号、扬麦20面粉和鲜面片色泽均比较好,亮度高,黄度低,携有优异等位变异;川麦42是优异的低黄度种质资源,但亮度需提升。面粉和鲜面片的L~*值间、a~*值间、b~*值间均呈极显著正相关,L~*值与a~*、b~*值均呈极显著负相关,a~*值和b~*值无显著相关性。 Psy-A1主要引起鲜面片a~*值和b~*值显著变化;对a~*值的效应表现为 Psy-A1b Psy-A1a ;对b~*值的效应表现为 Psy-A1b Psy-A1a ; Ppo-A1 对面粉及鲜面片的b~*值、鲜面片放置2 h和4 h的L~*值有显著影响;对b~*值的效应表现为 Ppo-A1b Ppo-A1a ;对L~*值的效应表现为 Ppo-A1b Ppo-A1a 。4个等位变异组合仅对鲜面片黄度b~*值有极显著影响, Ppo-A1a/ Psy-A1a 基因型最高,其他三种基因型差异不显著。因此,改良小麦面粉和面制品色泽应注意淘汰 Ppo-A1a / Psy-A1a 基因型,高世代需加强面制品色泽的筛选鉴定。     

The Determination of Wheat Breadmaking Performance and Bread Dough Mixing Time by NIR Spectroscopy for High Speed Mixers

A non-invasive near infrared (NIR) technique has been used to identify changes in the development of bread dough during mixing. A Perten DA-7000 Diode Array NIR instrument with a fibre optic probe attachment was used. Both breadmaking and biscuit making varieties of wheat were examined. Doughs were mixed using a laboratory scale Chorleywood Bread Process (CBP) mixer and NIR spectra were gathered (one every 2 s). Flour quality data were used to determine the relationship between NIR and breadmaking quality attributes and to study varietal differences in breadmaking performance. Instrumental and sensory techniques were used to establish the important quality attributes of commercially and laboratory produced bread. NIR spectra and mixer torque were measured at different mixing times to obtain an overall picture of the mixing process from the initial hydration of the flour particles through optimum dough development until overmixing had occurred. Loaves were produced and assessed for volume by seed displacement and crumb structure using an image analysis technique. The dough elastic modulus was measured at a range of mixing times using a Bohlin VOR Rheometer. Comparison of results from the NIR spectra, dough properties and bread quality was carried out. Results revealed a relationship between the rheological properties of dough and the final quality parameters of bread. NIR was shown to have considerable merit in following dough changes during mixing which were related to final bread quality and thus has the potential to be used as an on-line method for controlling breadmaking mixers.     

Investigating the impact of α-amylase, α-glucosidase and glucoamylase action on yeast-mediated bread dough fermentation and bread sugar levels

Wheat flour is generally supplemented with α-amylases to increase maltose levels in bread dough and increase loaf volume. While the preference of yeast for glucose and fructose over maltose as substrate for fermentation is well documented, the impact of maltose versus glucose producing enzymes on bread dough fermentation kinetics and bread sugar levels is ill documented. Hence the impact of α-amylase, α-glucosidase and glucoamylase action on both aspects was investigated. Glucoamylase and α-amylase increase the total fermentable sugar content of dough, while α-glucosidase only affects the glucose/maltose ratio. Due to their effect on total fermentable sugar levels, addition of α-amylase or glucoamylase prolongs the total productive fermentation time, while this is not the case for α-glucosidase. In contrast to α-amylase, both glucoamylase and α-glucosidase supplementation leads to higher CO₂ production rates during the initial stages of fermentation. In the final bread product, different sugar levels are observed depending on the dosage and type of starch-degrading enzyme. The results of this study imply that long and short fermentation processes benefit from α-amylase and α-glucosidase addition, respectively, while glucoamylase supplementation is suitable for both long and short fermentation times.     

Significance of furosine as heat-induced marker in cookies

The effects of recipe formulation in terms of leavening agents (ammonium and sodium bicarbonates), sugars (sucrose and glucose), initial moisture content, and baking conditions (temperature and time) on furosine formation in cookies were studied. The cookies were baked at different temperatures for different times to monitor the progress of the early stage of the Maillard reaction. Change in furosine levels as an indicator of the Amadori products showed a typical kinetic behavior with a rapid increase to an apparent maximum followed by exponential decrease during baking. Initial water activity of cookie dough had no remarkable effect on the apparent maximum, but lowering the water activity decreased the time required to attain it. In addition, levels of furosine in the final product are highly correlated to the initial water content of dough at the same baking conditions. The levels of furosine attained were significantly lower in cookies composed of sucrose than in cookies composed of glucose. Early stage of the MR is rapidly overcome during baking as the Amadori product degraded in the advanced stage. Among the leavening agents, ammonium bicarbonate was the most effective for the progress of the Maillard reaction in cookies during baking.     

Significance of furosine as heat-induced marker in cookies

The effects of recipe formulation in terms of leavening agents (ammonium and sodium bicarbonates), sugars (sucrose and glucose), initial moisture content, and baking conditions (temperature and time) on furosine formation in cookies were studied. The cookies were baked at different temperatures for different times to monitor the progress of the early stage of the Maillard reaction. Change in furosine levels as an indicator of the Amadori products showed a typical kinetic behavior with a rapid increase to an apparent maximum followed by exponential decrease during baking. Initial water activity of cookie dough had no remarkable effect on the apparent maximum, but lowering the water activity decreased the time required to attain it. In addition, levels of furosine in the final product are highly correlated to the initial water content of dough at the same baking conditions. The levels of furosine attained were significantly lower in cookies composed of sucrose than in cookies composed of glucose. Early stage of the MR is rapidly overcome during baking as the Amadori product degraded in the advanced stage. Among the leavening agents, ammonium bicarbonate was the most effective for the progress of the Maillard reaction in cookies during baking.     

MRI evaluation of local expansion in bread crumb during baking

The aim of this study was to undertake a dynamic and quantitative evaluation of the local evolution of porosity in a section of bread using magnetic resonance imaging (MRI). A prototype of an oven compatible with continuous MRI acquisition had been previously developed and installed in the probe of the imager. Oil microcapsules, which provide a very different MRI signal to that obtained from the dough, were also incorporated in the dough before proving, and their position in the bread was monitored throughout baking. Microcapsules delimited dough layers of which initial thickness ranged from 7 to 20 mm. Monitoring of the expansion of these layers is presented and discussed.Local expansion of the lower part of the bread predominated, contributing to 82% of the overall expansion at an oven air temperature of 130 °C. This was related to a slight escape of gas in this region, favored by one-dimensional heat transport. When the crust was formed early, as for an oven air temperature of 182 °C, local expansion did not cease with the crust setting and occurred to the detriment of the other regions, which were compressed.     

茶叶粉对小麦面粉流变学及糊化特性的影响

为进一步提高茶叶在食品工业中的应用范围,以小麦西农538(中筋)为供试材料,分别添加0、2%、4%、6%、8%和10%的绿茶、红茶和黑茶3类茶叶粉于面粉中,并对其进行面团流变学特性及糊化特性分析。结果表明,3类茶叶粉均可显著改善面团的流变学特性及糊化特性。随着茶叶粉添加量的增加,面团吸水率均显著增大;添加2%~10%的绿茶粉及6%~10%的黑茶粉,面团的形成时间和稳定时间均显著提高,弱化度均显著降低。添加6%的绿茶粉时,面团的拉伸能量和最大拉伸阻力增幅均达到最大值,延伸度出现小幅度升高的拐点;添加4%的红茶粉,面团的拉伸面积显著增大,继续增加添加量则变化不明显;黑茶和红茶粉添加量分别大于4%和6%时,面团延伸度均显著降低。面粉中添加适量的茶叶粉可改善面粉的品质,绿茶粉的添加对面团网络结构形成速度和面团筋力的改良效果大于红茶粉和黑茶粉。面粉糊化的峰值黏度、低谷黏度、最终黏度、峰值时间、回生值随着茶叶粉添加量的增大均呈不同幅度的降低趋势;3类茶叶粉对面粉糊化的热稳定性具有不同程度的改善作用。     

Effect of Final Dough Temperature on the Microstructure of Frozen Bread Dough

The effect of final mixing temperature (16 °C and 31 °C) on the structure stability of frozen bread dough was examined by low temperature-scanning electron microscopy and the quality of bread made from them assessed. The presence of ice-crystals were determined in both doughs after freezing, by low-temperature S.E.M. The microstructures showed a slight increase in size and decrease in number of angular voids, representing ice-crystals, after 14 weeks storage at −20 °C. Loaves baked from frozen dough with a final mixing temperature of 31 °C were poorer in both gassing power and overall loaf quality than 16 °C doughs, after 14 weeks storage.     

The effect of mixing on glutenin particle properties: aggregation factors that affect gluten function in dough

Previously we reported that the SDS insoluble gel-layer: the Glutenin Macro Polymer (GMP) can be considered as a gel consisting of protein particles. These glutenin particles have a size of about 10⁻¹–10² μm and consist of HMW-GS and LMW-GS only. In GMP isolates from flour, the particles are spherical. In isolates from dough, glutenin particles have lost this shape. This seems relevant, since mixing disrupts the particles and the mixing energy required for dough development correlated with the glutenin particle size in flour. The question studied in this paper is how changes at a glutenin particle level affected the subsequent process of gluten network formation during dough rest and if this could be used to explain resulting dough rheological properties. To this end, we studied how various mixing regimes affected the dough properties during and after resting (elasticity). We cannot fully explain the differences in the final dough properties observed using parameters such as the quantity of GMP in flour, the quantity of re-assembled GMP in dough and the size of re-assembled glutenin particles. However, other parameters were found to be important: (1) the Huggins constant K′ reflecting the tendency of glutenin particles to interact at level II of the Hyperaggregation model; (2) the composition of glutenin particles affecting the potential to form smaller or larger particles and (3) for over-mixed dough, covalent re-polymerisation at the so-called level I of hyperaggregation. Using these parameters we can better explain dough viscoelasticity after resting.     

The impact of redox agents on further dough development,relaxation and elastic recoil during lamination and fermentation of multi-layered pastry dough

The role of gluten proteins during lamination and fermentation of multi-layered wheat flour pastry dough was examined by including oxidizing or reducing agents in the recipe to respectively strengthen or weaken the gluten protein network. Pastry burst rig textural measurements showed that dough strength increases during lamination up to 16 fat layers. However, further lamination up to 64 and 128 fat layers decreases the dough strength, most likely due to destruction of layer integrity. Redox agents strongly affect dough strength. Furthermore, fermentation and spread tests showed that they strongly influence elastic recoil immediately after lamination and during relaxation. Moreover, elastic recoil consistently occurs to a greater extent in the final direction of sheeting. None of the observed changes in dough strength and relaxation behaviour could be linked to changes in the levels of protein extractable in sodium dodecyl sulfate containing medium (SDS-EP). This suggests that changes occur preferentially either within the SDS-extractable or within the non-SDS-EP fraction and that they do not render non-extractable protein fractions extractable or vice versa. Furthermore, elastic recoil is most likely caused by reformation of inter- and intramolecular hydrogen bonds and hydrophobic interactions.     

Correlation of glutenin macropolymer with viscoelastic properties during dough mixing

Although significant correlations exist for glutenin macropolymer (GMP) quantity and rheological properties/bread making quality of dough, little information about these links is available. The relationship between GMP contents measured by UV absorption method/RP-HPLC and dough viscoelastic properties determined by TA-XT2i texturometer from three wheat varieties (Xiaoyan6, Yumai56 and Zhengnong8805) during mixing was investigated. GMP contents of doughs decrease significantly (P<0.05) during mixing. During the initial mixing stage, amounts of the HMW-GS and LMW-GS and GMP decrease significantly (P<0.05). Their contents begin to increase beyond peak dough development time (DDT). This indicates that during further mixing after peak DDT some glutenin subunits are incorporated into GMP by repolymerization. The HMW/LMW-GS ratio has a significant effect on load-deformation properties (area, resistance and extensibility) of dough. The varieties behaved differently in relation to the contribution of their HMW-LMW-GS ratio to the rheological properties.     

How manipulation of wheat bran by superfine-grinding affects a wide spectrum of dough rheological properties

The present study explored the effect of size reduction by superfine grinding on the performance and rheological properties of bran-enriched dough. Coarse (D₅₀ = 328.98 μm) and superfine-ground (D₅₀ = 50.76 and 28.37 μm) wheat brans were incorporated into the wheat dough to replace 10–30% of plain flour. Both fundamental and empirical tests were performed to assess the mixing properties, pasting properties, large deformation rheology, small deformation rheology, and stickiness of the dough. With the increasing amount of bran added, dough water absorption capacity increased, while the dough became less sticky and more rigid. Superfine grinding reduced the water retention capacity of the bran by 17–20%. Dough fortified with the finest bran (D₅₀ = 28.37 μm) showed an overall better stability and uniaxial extensibility. However, the results suggested that superfine grinding not necessarily improve every aspect of dough performance, particularly the pasting properties. High peak and final viscosity were observed for dough fortified with superfine bran, indicating their end products, such as noodle, might exhibit high stickiness after cooking, and a high degree of starch retrogradation. Results of this study contributed to a better understanding of the modification effect of superfine grinding on dietary fibre.     

Dough and bread made from high- and low-protein flours by vacuum mixing: Part 2. Yeast activity,dough proofing and bread quality

The combined effects of reduced mixer headspace pressure and mixing duration on the yeast activity, proofing and quality of dough and bread made from both high-protein flour (HPF) and low-protein flour (LPF) were addressed in this study. Rheofermentometer analysis showed that a reduction in mixer headspace pressure up to 0.08 MPa did not affect the overall gassing power of yeast in either of the two dough matrices. An increase in mixing duration sped up the mass transfer rate of CO₂ at the initial stage of fermentation, leading to a faster expansion of dough volume at the beginning. Moreover, an increase in mixing time promoted dough development and gas inclusion, which resulted in a increased volume of dough and bread, as well as a softer texture of both baked bread and steamed bread. In general, reduced headspace pressure produced baked bread of smaller volume, denser structure and harder texture. On the other hand, vacuum mixing produced steamed bread with softer texture without significantly changing the bread’s volume and porosity.     

Expansion capacity of doughs: methodology and applications

An instrument for measuring the expansion capacity of dough was developed based on the application of a known negative pressure and measurement of the height reached by the dough using a dough height tracker. At a negative pressure of 74 cm of Hg, the same maximum heights were reached after expansion at all stages of processing from after mixing to end of proof. For this negative pressure (74 cm Hg), the expanded dough heights measured immediately after mixing for doughs from 9 hard and 10 soft wheat flours coincided closely with the heights reached by corresponding baked loaves (r=0.99). Pizza doughs were also found to give a good correlation with baked pizza height (r=0.78, significant at 1% level). The method was used to obtain information about the timing of the effects of bromate addition and flour lipid extraction during processing. An increase in dough expansion capacity from bromate addition was observed only after the final proofing stage. Gas cell fineness of the bread crumb, measured by CrumbScan software, was decreased by bromate addition but gas cell elongation was increased. Effects of lipid removal were different. An increase in expansion capacity occurred at all processing stages and gas cell fineness of the bread crumb was increased. Expansion capacity appears to be an inherent property of a dough and may have potential as a rapid measurement to predict baking performance.