How Do Xanthan and Hydroxypropyl Methylcellulose Individually Affect the Physicochemical Properties in a Model Gluten‐Free Dough?

To better understand the physicochemical changes imparted by hydrocolloids on gluten-free dough, 2 hydroxypropyl methylcelluloses (HPMCs) and xanthan gum were added at 2%, 3%, and 5% to rice cassava dough without the addition of alternative proteins. The formulated doughs were analyzed using thermoanalytic and rheological techniques to determine the role of water and subsequent flow behavior upon hydrocolloid addition. The baked loaves were then measured for specific loaf volume and tensile strength to determine bread quality. Thermogravimetric analysis (TGA) results revealed that hydrocolloid-added dough held water more tightly than the rice cassava control with an additional water distribution at 85 to 88 °C. Rheologically, the increase of elastic moduli in the low methoxy HPMC and xanthan-added dough became more pronounced with gum addition; however, both HPMC formulations had increased viscous moduli allowing the gas cells to expand without collapsing. In the bread, the final specific loaf volume increased with high methoxy HPMC (2% to 5%) and low methoxy HPMC (2%) but was depressed with increased addition of low methoxy HPMC (5%) and xanthan (3% and 5%). Crumb hardness was decreased in high methoxy HPMC loaves but was increased significantly in low methoxy HPMC (5%) and xanthan (5%) formulations. From the gums studied, it was concluded that high methoxy HPMC was the optimum hydrocolloid in the rice cassava gluten-free dough. PRACTICAL APPLICATION: Two types of hydrocolloids, xanthan gum and HPMC, were individually added to a gluten-free rice cassava formulation. Based on the thermoanalytic and rheological studies on dough, as well as the bread quality studies, high methoxy HPMC at 5% addition was determined to optimally improve the bread quality when only gum addition was considered. This study indicates the potential use of high methoxy HPMC as an additive in gluten-free bread formulations prior to considering alternative proteins.     

Effect of zein protein and hydroxypropyl methylcellulose on the texture of model gluten‐free bread

The influence of zein protein and hydroxypropyl methylcellulose (HPMC) on the texture and volume of gluten‐free bread was investigated. The addition of HPMC to starch affected the dough viscoelasticity and it improved the bread volume during baking since it acts as an emulsifier. The addition of zein protein to gluten‐free bread increased the crumb firmness and reduced the crust hardness within the range of concentrations investigated. No zein protein network could be observed in the bread crumb. The zein protein, cold mixed at low concentration, did not enhance the dough elasticity. Due to the lack of a protein network noncovalent interactions may stabilize the bubble structure stabilization within the crumb, rather than covalent links of the protein chain. With an optimized amount of zein protein and HPMC hydrocolloid, the gluten‐free bread showed similar texture and staling behavior to that of model wheat bread. The optimized recipe, compiled into a spreadsheet, is available in the supporting information. The microstructural observations suggest that zein could be replaced with another protein for this recipe resulting in a similar bread texture.     

Antistaling Additives, Flour Type and Sourdough Process Effects on Functionality of Wheat Doughs

Antistaling additives—distilled monoglycerides (MGL), diacetyl tartaric ester of monodiglycerides (DATEM), sodium stearoyl lactylate (SSL), carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC) and fungal α-amylase—were studied for effects on rheological and fer- mentative properties of white/whole wheat bread doughs, made following straight/sour dough processes. A fractionated factorial design (L³²) was used to evaluate single additive effects and interactions. Single addition of DATEM, followed by SSL, α-amylase and hydrocolloids improved oven rise and final volume. In presence of DATEM, synergistic (MGL) and antagonistic (SSL) effects of additional emulsifiers were found on gassing power. SSL was the only effective conditioner for enhancement of mixing properties. Dough plasticity was negatively affected by MGL addition and by CMC/HPMC in white/whole flours respectively. Some combinations resulted in detrimental dough handling properties.     

食品添加剂对面团动态流变学及冷冻面团烘焙特性的影响研究

应用动态流变仪,研究了食品添加剂硬脂酰-2-乳酸钠(SSL)、刺槐豆胶(LBG)、葡萄糖氧化酶(GOD)、木聚糖酶(XY)及葡萄糖氧化酶和木聚糖酶(GOD+XY)复合对面团动态流变学特性以及对冷冻面团烘焙特性的影响。结果表明,在频率0.1～40Hz扫描过程中,与未添加任何添加剂的面团(空白面团)相比,添加SSL的面团弹性模量、粘性模量和损耗角正切都减小;添加LBG的面团弹性模量和粘性模量增大,损耗角正切减小;添加GOD的面团弹性模量增大,粘性模量和损耗角正切减小;含有XY的面团弹性模量和粘性模量减小,损耗角正切增大;而含有GOD+XY的面团弹性模量和粘性模量增大,损耗角正切减小。升温扫描过程中,在低于55℃时弹性模量和粘性模量变化较小。随温度的升高,大约从55℃开始弹性模量和粘性模量迅速增加到最大值,然后又快速降低。采用6个配方研究了不同添加剂及其不同配比对冷冻面团烘焙特性的影响,实验发现酶制剂、乳化剂及胶体复合明显提高了冷冻面团的烘焙特性,缩短了醒发时间、增大了面包比容和降低了面包瓤硬度,这表明酶制剂、乳化剂和胶体在面团体系中存在协同增效的作用。     

IMPROVEMENT OF THE WHEAT AND CORN BRAN BREAD QUALITY BY USING GLUCOSE OXIDASE AND HEXOSE OXIDASE

The effects of addition of wheat (10, 20 and 30%) and corn bran (10 and 20%) on rheological and bread making properties of flour were examined. To improve dough and bread properties, glucose oxidase (GO) and hexose oxidase (HO) (15–30 and 45 mg/kg) were used separately in each bran-wheat flour formula with L-ascorbic acid at 75 mg/kg, glucose at 0.5% and vital gluten at 9.2%. Water absorption and development time increased as the amount of wheat and corn bran increased, while dough stability, maximum resistance to extension, extensibility, energy and loaf volume decreased. Corn bran was found to be more detrimental to dough rheology and bread characteristics than wheat bran. Corn bran and wheat bran could be used at bread making up to levels of 10 and 20%, respectively. Addition of 30 mg/kg of HO in combination with constant additives was most effective in improving dough and bread characteristics and GO with its 15 mg/kg usage level followed it. Further increasing of enzyme levels led to over oxidizing of doughs and breads.

PRACTICAL APPLICATIONS

Corn bran up to 10% and wheat bran up to 20% levels can be used in bread making. To improve dough and bread quality, besides L-ascorbic acid (75 mg/kg) and vital gluten (as a percentage of added bran weight), GO (15 mg/kg) or HO (30 mg/kg) could be incorporated into wheat flour-bran mixtures. However, the amount of enzyme should be carefully chosen because when they are used above the mentioned levels, they cause overoxidation of doughs and small loaf volumes are obtained. As a conclusion; by using the corn bran, which is a by-product of the starch industry, not only could it be possible to offer healthy alternative breads which contain high amounts of dietary fiber to consumers, but it could also be possible to obtain economical value by evaluating such a by-product in the bread industry.     

Influence of repeated extrusions on some properties of non-conventional spaghetti

The influence of the re-extrusion (repeated extrusion) number on the rheological properties of non-conventional doughs, mechanical and sensorial characteristics of dry spaghetti was investigated. Moreover, the dough gelatinization degree was also evaluated. Amaranth, oat and quinoa flours were used to produce the spaghetti samples. Twelve non-conventional spaghetti samples were manufactured varying the re-extrusion number. The rheological properties of doughs were determined using a capillary rheometer, the mechanical characteristics of dry spaghetti by a dynamic mechanical analyzer and the sensorial parameters by a trained panel. The re-extrusion number affected the extensional and shears viscosity of amaranth, oat and quinoa dough samples. The breaking strength of dry non-conventional spaghetti increased with the increase of the re-extrusion number for amaranth and oat. The dough gelatinization degree of the quinoa and oat significantly increased with the re-extrusion, whereas no influence of re-extrusion was found for the amaranth dough. Moreover, the re-extrusion number improved sensorial color and homogeneity for oat and quinoa dry spaghetti and had no effects on the sensorial characteristics of all cooked spaghetti.     

Effects of soy protein isolate and egg white solids on the physicochemical properties of gluten-free bread

Gluten-free formulations are often supplemented with proteins to improve their quality. To determine the effects of alternative proteins on a hydroxypropyl methylcellulose (HPMC)-treated gluten-free dough system, soy protein isolate was added at 1%, 2% and 3% while egg white solids were investigated at 5%, 10% and 15%. The formulated doughs were analysed using thermoanalytic and rheological techniques to determine the role of water and subsequent flow behaviour upon hydrocolloid addition. The baked loaves were measured for specific loaf volume and tensile strength to determine bread quality. The addition of soy protein isolate and egg white solids (5% and 10%) reduced dough stability by suppressing HPMC functionality, reducing available water, weakening HPMC interactions with the starch matrix and reducing foam stability. At 15% addition, egg white solids became the primary protein scaffolding in the dough and overcame negative interactions with HPMC, improving the loaf volume. However, this formulation may need further optimisation to meet full consumer acceptability.     

Rheological and physical evaluation of jet‐cooked oat bran in low calorie cookies†

Different levels of shortening in cookies (10%, 20% and 30% by weight) were replaced with 20% jet‐cooked oat bran, also called Nutrim oat bran (OB), to prepare cookies with fewer calories. The cookies containing Nutrim OB were investigated in terms of rheological and physical properties and compared with a control. As more shortening was replaced with Nutrim OB, a decrease in the diameter and an increase in the height of cookies were observed. The increased moisture content from Nutrim OB caused a decrease in the dynamic viscoelastic properties of cookie dough. Squeezing flow method showed shear thinning behaviours in all cookie doughs. Also, the elongational viscosity of cookie dough decreased significantly with more replacement of shortening with Nutrim OB. The rheological properties of cookie dough during baking indicated that all of the samples had similar types of viscoelastic characteristics during baking. However, the cookies containing more Nutrim OB exhibited more elastic properties which resulted in a decreased cookie diameter. There was no significant difference in cookie hardness among samples with up to 20% shortening replacement but the cookies became lighter in colour as the Nutrim OB content was increased.     

Effect of Wheat Bran Particle Size on Dough Rheological Properties

Commercial hard red spring, hard red winter, soft white and durum wheat brans were used to investigate the effect of wheat bran particle size on the rheological properties of doughs. Wheat brans were first coarsely ground and passed through a bran finisher to remove additional endosperm and aleurone layers. These processes increased total dietary fibre content and decreased starch content of the wheat bran samples. Three particle size distributions, for each wheat bran class, were obtained by further grinding (not by sifting) of the bran samples by different experimental mills. Coarse bran can retain significantly more water than medium or fine bran as measured by a centrifuge method, but bran particle size had no significant effect on dough water absorption. Addition of wheat bran into bread dough systems increased dough water absorption rate, reduced mixing time and decreased dough mixing tolerance as measured by farinograph. Fine particle size wheat bran decreased dough mixing tolerance and reduced mixing time compared to coarse bran. Dough containing fine particle size bran exhibited more strength than dough containing coarse bran after a 180-min rest period as measured by the extensigraph. © 1997 SCI.     

燕麦麸皮对馒头品质的影响

将不同比例的燕麦麸皮添加到小麦粉中,研究其对面团流变学特性和对馒头品质的影响。实验结果表明,向面粉中适量地添加燕麦麸皮,蒸制出的馒头其体积、质量和风味都有所增加,感官评分提高,表面变得光滑、对称、挺立,具有球形感,且内部气孔细小均匀。燕麦麸皮在不同添加量的条件下所制得的馒头感官评分结果为:燕麦麸皮添加量为5%时,馒头感官评价得分最高。相同添加量下的燕麦麸皮和小麦麸皮所制得馒头感官评分结果为:添加量为5%的燕麦麸皮所制的馒头感官评分结果高于添加量为5%的小麦麸皮所制的馒头感官评分结果。     

INFLUENCE OF GUMS ON DOUGH PROPERTIES AND FLAT BREAD QUALITY OF TWO PERSIAN WHEAT VARIETIES

The effects of separate mixing of two hydrocolloids carboxymethylcellulose (CMC) and hydroxypropylmethylcellulose (HPMC) at 0.1, 0.3 and 0.5% levels with Sardary and Sorkheh wheat flours (two native Persian varieties) were studied. Chemical and rheological (Farinograph and Extensograph) tests, staling and sensory evaluations were performed on the two flours, their dough and the resulting Lavash flat bread, respectively. On the basis of split‐plot experiment in a complete random design and using the Duncan's multiple range tests, the data were evaluated and the average of replicates was compared at the statistical level of 1% (α = 0.01). Although the CMC and HPMC gums enhanced significantly the dough quality of the two wheat varieties by increasing water absorption and reducing resistances after 90 and 135 min (compared with control), the effect of HPMC was more pronounced than CMC. Anti‐staling properties of HPMC were better than CMC, especially for Sardary flour. Separate addition of 0.5% CMC and HPMC gums to Sorkheh and Sardary flours significantly delayed the staling process of the resulting Lavash bread by more than 45 and 42%, respectively. Additionally, sensory evaluation scores of the Lavash bread made from either Sorkheh flour containing 0.3% CMC or HPMC or Sardary flour containing 0.5% HPMC were 50 and 120% higher than control bread samples, respectively.     

品质改良剂及燕麦酸面团对燕麦面团黏弹特性的改善

采用动态流变仪初步探讨添加不同量的羟甲基丙基纤维素（hydroxy propyl methyl cellulose,HPMC）、黄原胶、乳清粉、大豆分离蛋白、燕麦酸面团对燕麦面团动态流变学特性的影响。结果表明：在频率0.01～10 Hz扫描过程中,与未添加任何配料的燕麦面团相比,添加不同量HPMC或燕麦酸面团的燕麦面团弹性模量、黏性模量均增加,且添加HPMC的燕麦面团损耗因子也有所增加,其中添加0.5% HPMC和30%燕麦酸面团对燕麦面团黏弹特性的改善作用最佳;添加0.2%黄原胶、5%乳清粉、5%和10%大豆分离蛋白对燕麦面团的动态流变学特性无明显影响,而添加10%、15%乳清粉或15%大豆分离蛋白时,燕麦面团弹性模量、黏性模量反而降低。     

Comparison of uniaxial/biaxial extensional rheological properties of mixed dough with traditional rheological test results: relationship with the quality of steamed bread

The formula and preparation of steamed bread are different from those of western bread. The extensional rheological behaviour plays a key role in the development of steamed bread dough. However, there are inadequate studies on the rheological properties of mixed dough with yeast. In this study, the relationship between properties of dough in the presence or absence of yeast was elucidated. Besides, the flour characteristics and quality of steamed bread prepared from different wheat varieties were evaluated. The uniaxial/biaxial extensional rheological properties of wheat dough were compared with traditional rheological test results. Large deformations in the extensional properties were measured by Extensograph and the Kieffer extensibility rig, while the biaxial extension was quantified using uniaxial compression. These characteristics of dough and flour correlated with each other in different ways. Correlation analysis illustrated that the uniaxial extensional rheological properties of dough with yeast better indicated the quality of the steamed bread. Moreover, the total work for breakage of the dough with yeast was the best predictor for specific volume of steamed bread. The texture-based properties of steamed bread showed correlation with biaxial extension viscosity. The rheological tests provide useful information for evaluating wheat flour and steamed bread quality.     

Effect of Carob Flour Addition on the Rheological Properties of Gluten-Free Breads

In this study, the rheological properties of gluten-free doughs from rice flour containing different amounts of carob flour were investigated. Water added changed in response to the carob amount. Dynamic oscillatory and creep tests were performed in order to gain knowledge on the rheological behaviour of doughs, which is essential for the control of the bread-making procedure and the production of high-quality bread. Simple power law mathematical models were developed in order to evaluate the effect of carob and water added in dough rheological behaviour. Creep data evaluation demonstrates that an increase in water content decreased the resistance of dough to deformation and, therefore, dough strength, whereas carob flour increased the elastic character and structure strength of the dough. This was also found in dynamic oscillatory tests. Increased amounts of carob flour led to an increase in bread dough elastic character since fibre addition elastifies and strengthens the dough structure. Moreover, doughs exhibited a solid-like viscoelastic character, with the storage modulus (G′) predominant over the loss modulus (G″). Dough rheological properties have an important effect on baking characteristics. Rheological experiments and applied mathematical models can provide us with good knowledge of rheological behaviour and dough viscoelasticity prediction. Therefore, dough samples containing carob-to-water ratios of 10:110 and 15:130 can be considered to possess a balance between the viscous and elastic properties compared to the other samples.     

Effect of hydrocolloids on the rheological, microscopic, mass transfer characteristics during frying and quality characteristics of puri

Effect of hydrocolloids such as guar gum (GG), arabic gum (AG), carrageenan (CG), locust bean gum (LBG), xanthan gum (XN), hydroxypropyl methylcellulose (HPMC) and carboxymethylcellulose (CMC) at 0.5% w/w level on rheological and quality parameters of puri from whole wheat flour was studied. Hydrocolloids like CMC, XN and HPMC increased the water absorption of puri dough, while it decreased in all other samples. The dough development time and mixing tolerance index values increased, while dough stability did not get affected. On addition of hydrocolloid, there was a reduction in the pasting temperature, while the peak viscosity, hot paste viscosity and cold paste viscosity values increased. Hardness, cohesiveness and adhesiveness properties of the puri dough increased with the addition of hydrocolloids. All the hydrocolloids used in general helped in retention of moisture in the puri and hence remained softer and pliable, while there was a significant reduction in the oil content of puri samples containing hydrocolloids. Among the different hydrocolloids used, addition of guar gum at 0.5% w/w level led to puris having improved quality characteristics to a greater extent with respect to moisture retention, lowering of oil content upon frying with softer and pliable texture and better keeping quality. The mass transfer studies confirmed that the mass transfer co-efficient values for moisture loss and oil uptake were lower in puris with guar gum than control.     

Effect of Salt and Ethanol Addition on Zein–Starch Dough and Bread Quality

Development of viscoelastic doughs from non‐wheat proteins allows for a wider range of gluten‐free products. Little work has been completed to describe mechanisms of zein functionality in food systems. To identify factors responsible for dough development in zein–starch mixtures and their influence on zein bread quality, a mixture of 20% zein–80% maize starch was mixed with water and various reagents. Salts, NaSCN, NaCl, and Na₂SO₄ were evaluated at concentrations from 0 to 2M for their influence on the properties of zein–starch dough systems. NaSCN at low concentrations produced softer dough. Ethanol treatments produced softer more workable dough in the absence of salts. Increasing concentrations of NaCl and Na₂SO₄ resulted in coalescing of the proteins and no dough formation. The addition of β‐ME had minimal softening effects on zein–starch dough. Specific volumes of zein–starch bread increased with decreasing NaCl addition in bread formulations. Likewise, including 5% ethanol (v/v) in the bread formula increased bread quality.     

Impact of sourdough, yeast and gluten on small and large deformation rheological profiles of durum wheat bread doughs

The impact of percentage of sourdough (SD) addition and presence of yeast (Y) and/or commercial wheat gluten (G) -added singly and in binary combination- on both small and large deformation rheological performance and viscometric profile of durum wheat bread doughs was considered. Eight distinctive rheological dough features were identified as able/capable to clearly differentiate soured bread doughs made with semolina:remilled semolina rate of 80:20 into defined functional quality groups. The presence of added commercial wheat gluten provided firmer, more elastic and more extensible doughs with slightly lower viscometric profile. Simultaneous presence of yeast/sourdough and yeast/gluten modulate single effects of sourdough on the durum wheat bread dough mechanical properties. Several relationships were found between fundamental and empirical rheological properties and within viscometric features of soured semolina doughs.     

Fibre-rich additives--the effect on staling and their function in free-standing and pan-baked bread

BACKGROUND: The use of dietary fibre in bread products is increasing because of consumer demand for healthier products. However, an increase in dietary fibre level changes the rheological properties of the dough and also the quality properties of the final bread product. In this study, effects on dough and bread staling were followed after replacing 3% of wheat flour by fibre‐rich additives (fine durum, oat bran, rye bran and wheat bran). Free‐standing and pan‐baked loaves were baked to compare the influence of baking method and loaf shape. RESULTS: All additives increased dough stability, with oat bran giving the greatest stability and longest development time. Parameters measured during storage were distribution, migration and loss of water, cutability, crumbliness, firmness and springiness. Furthermore, amylopectin retrogradation and amylase‐lipid complex formation were assessed. Oat bran provided similar or better results than the control for all staling parameters, while other additives gave no general improvements. Cutability reached a plateau when crumb firmness was ≥ 4 N. CONCLUSION: Small amounts of fibre‐rich additives had a significant influence on staling. However, the baking method (free‐standing or pan‐baked bread) had a greater impact on staling than the additives, thus displaying the importance of the baking method. Cutability was found to be related to firmness. Copyright © 2011 Society of Chemical Industry     

发酵麦麸对面包面团生化特征及烘焙学特性的影响

采用马克斯克鲁维酵母(Marx Kluyveromyces)发酵麦麸,通过生化分析、流变特性测试及微观结构观察(Scanning electron microscope,SEM)等多种分析手段,研究其对面包面团生物化学特征和烘焙学特性的影响。结果表明:马克斯克鲁维酵母发酵麦麸中富含多种天然酶,主要包括纤维素酶、木聚糖酶和阿魏酸酯酶;水解酶在面包制作过程中持续作用,促进木聚糖溶解和酚类化合物释放,赋予面包较高的营养价值;与仅添加木聚糖酶的麦麸面包面团相比,马克斯克鲁维酵母发酵麦麸面包面团具有更好的持气性及连续的面筋网络结构,面包全质构特性和比容显著提升。研究结果显示,马克斯克鲁维酵母发酵麦麸可以作为一种天然面包功能配料。     

Flour Quality effects on percolation of gas bubbles in wheat flour doughs

To investigate how flour affects crumb structures, we used Synchrotron X-ray tomography to scan and capture the growth of gas bubbles in leavened and unleavened bread doughs of two different flours. Bubbles were mobile in all doughs; they coalesced and disproportionated with the rate of coalescence being higher in leavened doughs. In unleavened dough, new bubbles were detected, attributed to arise from poro-visco-elastic relaxation of gluten as dough rested. In each yeasted dough, a single, massively inter-connected cluster formed which percolated at ~26% dough porosity irrespective of flour type in dough. Following percolation, dough expansion was driven primarily by growth of the percolating bubble. Between flours, the rate of coalescence was higher in Wylkatchem (Wylk), an Australian flour dough, than in Canadian Western Red Spring (CWRS) flour dough, known for superior proof and bake qualities. How the physical and rheological properties of dough liquors could have affected the stabilities of bubbles in these doughs have been discussed.