Effect of flour heating on dough rheology

Heating soft wheat flour at 80°C for 15 min has already been shown to improve its bread-making potential. In this study, flour was fractionated to determine the specific effect of heating on its constituents (gluten, starch, lipid, water-soluble). While gluten was easier to extract and its texture was slacker after heating, it significantly increased dough-mixing stability and development time (P<0.01). Heated water-soluble fraction containing pentosans partly decreased stability (P=0.06).     

Glucose oxidase effect on dough rheology and bread quality: A study from macroscopic to molecular level

Enzymes are used in baking to improve dough handling properties and the quality of baked products. Glucose oxidase (GO) is an enzyme with oxidizing effect due to the hydrogen peroxide released from its catalytic reaction. In this study, the macroscopic effect of increasing glucose oxidase concentrations on wheat dough rheology, fresh bread characteristics and its shelf life during storage was determined. A reinforcement or strengthening of wheat dough and an improvement of bread quality can be obtained with the addition of GO, although inverse effects were obtained when excessive enzyme levels were added. The analysis of the gluten proteins at molecular level by high performance capillary electrophoresis and at supramolecular level by cryo-scanning electron microscopy revealed that the GO treatment modified gluten proteins (gliadins and glutenins) through the formation of disulfide and non-disulfide crosslinks. The high molecular weight glutenin subunits showed to be the most susceptible glutenin fraction to the oxidation action of GO. Excessive addition of GO produced an excessive crosslinking in the gluten network, responsible of the negative effect on the breadmaking properties.     

Effect of chemical composition of wheat flour and functional properties of dough on the quality of south Indian parotta

Six flours differing in quality were analysed for their chemical and rheological parameters. South Indian parottas were prepared and evaluated for their textural characteristics using an Instron universal testing machine (UTM) and their sensory characteristics by a trained panel. The correlation coefficient data indicated that among the chemical characteristics of flours, dry gluten, protein and SDS sedimentation value were found to be the best indices in predicting the quality of parotta. The rheological characteristics, such as farinograph water absorption, extensograph ratio figure and area, and Instron apparent biaxial extensional viscosity (ABEV), hardness and cohesiveness were found to be highly correlated to the overall quality score of parotta. Sensory texture of parotta was found to be highly correlated to shear force as well as compression force (r=0.99, P ≤ 0.001) indicating that shear and compression forces could be considered as the best indices of sensory texture of parotta.     

Effect of α-amylases on dough properties during Turkish hearth bread production

Summary The effect of α‐amylases from cereal and fungal sources on dough rheological properties was studied. Increasing the enzyme addition level to 160 SKB units (c. 1.1%, fwb) decreased dough stability and increased mixing tolerance indexes. Gas production rates with cereal α‐amylase were higher than that with fungal α‐amylases, indicating more activity during fermentation. A higher adsorption rate occurred with cereal α‐amylase. Dough stability is very important for Turkish hearth bread production, as it is for other hearth breads. Spread ratio tests on fermented doughs showed significant changes in dough rheological properties as a function of α‐amylases. The spread test is a reliable tool for observing rheological changes during fermentation. As a guide, the dough spread ratio should not be more than 2 for desirable bread.     

Bread quality and dough rheology of enzyme-supplemented wheat flour

The enzymatic treatment of wheat flours is an interesting alternative for improving their functional properties. Since enzymes with different biochemical activities could induce synergistic effects on dough behaviour or product quality, the individual and combined use of a wide range of enzymes (transglutaminase, glucose oxidase, laccase, α-amylase, pentosanase and protease) applied nowadays in bread-making processes were investigated. The blend of enzymes resulted in an improvement in the rheological behaviour of doughs and the quality of the final product. The simultaneous presence of transglutaminase (TG) and glucose oxidase (GO), as well as TG and protease (PROT) led to a synergistic effect on alveograph parameters. Polysaccharide-degrading enzymes exercised a significant effect on rheology only when used in combination with other enzymes, mainly affecting consistograph parameters. Analysis of bread-making data revealed significant interactions between TG and all the other enzymes except laccase (LAC). Significant synergistic effect on bread quality was observed by the combined use of GO and LAC, GO and pentosanase (PP), amylase (AMYL) and LAC, AMYL and PROT, and PP and PROT. Bread quality parameters showed greater correlations with alveograph parameters than with consistograph properties of dough. Tenacity (P) and extensibility (L) proved to be acceptable predictors of the height/width ratio of loaves. The duration of the alveograph test enhanced the prediction of bread quality parameters. Conversely, none of the rheological properties studied showed a high correlation with the specific volume of loaves.     

Modelling of dough formation process and structure evolution during farinograph test

Dough formation process is a relevant step in cereal goods manufacturing, as in this stage the material develops its mechanical properties. Dough structure formation is promoted by mechanical energy transfer from the mixer blades to the sample, affecting flour hydration and gluten network formation kinetics. This paper reports a model of dough formation process during a farinograph test, accounting for all relevant physical phenomena: wheat particles hydration, gluten network formation, evolution and (eventually) disruption as effect of mixing energy. Results of the model are in terms of network strength and connectivity evolution, and a qualitative agreement was found with typical farinograph results. This allowed to employ the model to study the effect of the flour's physical properties on the empirically defined (but employed as industrial standards) farinograph outputs. Therefore, simulation results allowed to gain a physical insight of the technological parameters from a farinograph test.     

Effects of hydroperoxide in lipid peroxidation on dough fermentation

The effects on dough fermentation of hydroperoxides produced by lipid peroxidation through lipoxygenase induction were studied. The mechanism by which hydroperoxides accelerated dough fermentation was also investigated. Dough with lipoxygenase had a significantly increased amount of hydroperoxides after 90 min of fermentation, while dough without lipoxygenase had less generation of hydroperoxides until 30 min, after that time hydroperoxide generation decreased gradually. A hydroperoxide concentration of 30–40 mM had the greatest effect on accelerating dough fermentation. In the dough with hydroperoxides, the maximum expansion rate occurred with a 1% yeast concentration and a gluten concentration of 60%. The mechanism of dough fermentation using lipid peroxidation by lipoxygenase induction is discussed in detail. Gluten is formed from gliadin and glutenin. Gluten was denatured by hydroperoxides, which makes the gluten molecule grow larger (molecular weight of approximately 53 kDa). Fermentation is promoted by this phenomenon. This information provides new information for the bread-making industry.     

Fermented milk obtained with kefir grains as an ingredient in breadmaking

The objectives of this research were to study the effect of the addition of lyophilised kefir milk to premixes for household production of bread and evaluate the quality attributes of them. Four lyophilised samples were obtained from the followings: skim milk, acidified skim milk, fermented skim milk and neutralised fermented skim milk. Breads were prepared with commercial wheat flour, lyophilised milk samples and yeast through a straight dough process. Quality was assessed through loaf volume, crumb porosity and moisture, crumb texture and crust colour. Changes in texture and starch recrystallisation by X‐ray diffractometry were determined after 1 and 3 days of storage at room temperature. Breads with acidified milks showed the highest specific volumes and crumbs with the best texture properties. Crystallinity in bread with fermented milks was higher than for skim milk sample. This would indicate that there would be a certain effect of the type of milk processing on the promotion of starch retrogradation.     

Functional effects of xanthan gum on composite cassava-wheat dough and bread

The use of composite flour for bread making is gradually gaining prominence worldwide due to some economic and nutritional reasons. However, studies on the application of functional ingredients purposely to improve composite bread quality are very few. This paper examines the functional role of xanthan gum (XG) on the properties of dough and bread from composite cassava-wheat flour. The viscoelastic properties of dough and gas retention characteristics of batter as well as the fresh and storage properties of bread from the composite flour (90% wheat plus 10% cassava) were studied. The crumb cell structure was also studied using digital image analysis technique. Inclusion of XG had significant effects on the dough tenacity and extensibility and sensory acceptability of fresh composite bread. The oven spring, specific volumes of bread loaf and crumb softness were higher at 1% XG content. Also, addition of XG made the composite bread samples had more open crumb structure and better sensory acceptability. However, moisture loss and crumb firming during bread storage were best reduced when 1% XG was added to bread formulation.     

Impact of mixing time and sodium stearoyl lactylate on gluten polymerization during baking of wheat flour dough

The impact of differences in dough transient gluten network on gluten cross-linking during baking is insufficiently understood. We varied dough mixing times and/or added sodium stearoyl lactylate (SSL; 1.0% on flour dry matter basis) to the recipe and studied the effect on subsequent gluten polymerization during heating. The level of proteins extractable in sodium dodecyl sulfate containing media was fitted using first order kinetics. The extent and rate of gluten polymerization were lower when mixing for 8 min than when mixing for 2 min. This effect was even more outspoken in the presence of SSL. The present observations were explained as resulting from less gliadin incorporation in the polymer gluten network and from interaction of SSL with the gluten proteins. Finally, a higher degree of gluten polymerization during baking increased the firmness of the baked products.     

Techno‐functional properties of wheat flour‐resistant starch mixtures applied to breadmaking

Resistant starch can be used to reduce the availability of carbohydrates in baked products. In this study, the effect of type 4 resistant wheat starch (RS₄) on wheat flour dough and breads was evaluated. Wheat flour was substituted by RS₄ at 10%, 20% and 30% w/w (RS10, RS20 and RS30, respectively). Rheological and thermal behaviours of dough were evaluated. Besides, bread quality, starch digestibility and bread staling were analysed. All substituted dough exhibited viscoelastic behaviour but lower elastic and viscous moduli. Regarding to bread quality, specific volume and crumb texture were negatively affected in samples with RS₄. However, all samples were technologically acceptable. During storage, crumb hardening was observed in breads without and with RS₄ but amylopectin retrogradation was not particularly affected. The in vitro digestibility of bread with RS showed a lower release of reducing sugars and a lower estimated glycaemic index, suggesting a healthier profile for these breads.     

Bran-induced changes in water structure and gluten conformation in model gluten dough studied by Fourier transform infrared spectroscopy

The impact of bran addition on the state of water and gluten secondary structure in gluten dough was studied using Fourier transform infrared spectroscopy to understand the underlying physical mechanism by which bran impacts dough properties. Comparison of the OH stretch band of water in gluten dough with that of H₂O–D₂O mixture having the same water content revealed formation of two distinct water populations in gluten dough corresponding to IR absorption frequencies at 3580 cm⁻¹ and 3180 cm⁻¹. The band intensity at 3180 cm⁻¹, which is related to water bound to gluten matrix, decreased with increase of moisture content of the dough. Addition of bran to gluten dough caused redistribution of the bound water in the gluten-bran dough system. This water redistribution affected the secondary structure of gluten in the dough as evidenced from changes in the second-derivative spectrum in the amide I region. In the hydrated state, β-turn (in the form of β-spiral) was the major secondary structure (∼60%) in gluten. Addition of bran to gluten dough caused conversion of β-spirals into β-sheet and random structures. However, the extent of this conversion in the presence of bran was inversely related to the moisture content of the dough. This study revealed that when bran is added to gluten dough, water redistribution promotes partial dehydration of gluten and collapse of β-spirals into intermolecular β-sheet structures; this trans-conformation might be physical reasons for the poor quality of bread containing added bran.     

Responses of breadmaking quality to sulphur in three wheat varieties

Field experiments were carried out at three sites in England to investigate the effects of S fertilisation on breadmaking quality of three winter wheat varieties (Hereward, Rialto and Spark) in the 1996–1997 season. The soils at the three sites differed in extractable S contents. Depending on site, either 180 and 230 kg ha⁻¹ N or 230 and 280 kg ha⁻¹ N treatments were factorially combined with three S treatments (0, 20 and 100 kg ha⁻¹ S). Addition of S increased loaf volume significantly at two sites where grain S concentration was also significantly increased and grain N:S ratio decreased. Application of the extra 50 kg ha⁻¹ N increased grain protein concentration but did not increase loaf volume at any of the sites. Loaf volume was found to correlate more closely with grain S than with grain protein concentration. Addition of S generally decreased the elastic modulus of gel protein and dough resistance but increased dough extensibility. Despite considerable differences in their dough rheology, the responses in rheology and loaf volume to S were similar in all three varieties. Selected flour samples of Rialto from the Bridgets site were also analysed for the glutenin subunit distribution, showing that S addition increased the relative proportion of low-molecular-weight subunits at the expense of high-molecular-weight subunits of glutenin. This study therefore shows that the beneficial effects of S on breadmaking quality are associated with decreased dough elasticity and increased extensibility resulting from effects on the amount and composition of the glutenin polymers. The results also indicate that S fertilisation is required in some areas of England to maintain breadmaking quality. © 1999 Society of Chemical Industry     

Evaluation of Lepidium sativum seed and guar gum to improve dough rheology and quality parameters in composite rice–wheat bread

The effects of hydrocolloids in rice–wheat flour were studied. Hydrocolloids at 0%, 0.3%, 0.6% and 1% w/w (flour basis) and guar (G), Lepidium sativum seed (L) and guar-L. sativum seed (GL) gum were tested as additives to the rice/flour in various combinations. The quality parameters for the experiment were assessed with farinography, extensography, amylography and texture profile analysis. The evaluation of dough rheology showed that water absorption, dough development time, dough stability and viscosity all increased with the addition of hydrocolloids alone or in a combination. It was demonstrated that G₁L₁ promoted the highest effect. The mixing tolerance index and gelatinization temperature decreased with an increased hydrocolloid concentration. Extensibility value for the dough that incorporated guar and L. sativum seed gum increased with increasing hydrocolloid concentration from 0.3% to 0.6% and then decreased at 1%. The water activity of all bread didn't have significant differences with increasing hydrocolloids concentration but this parameter 24 decreased during storage. Firmness decreased with increasing hydrocolloid concentration and increased with increasing storage time. The sensory evaluation by a consumer panel gave the higher score for overall acceptability to G_0.3L_0.3 and G_0.3L_0.6 samples. The results also showed that G₁L₁, G₁L_0.6 and G_0.6L₁ samples had high specific volume and porosity.     

Dough aeration and rheology: Part 3. Effect of the presence of gas bubbles in bread dough on measured bulk rheology and work input rate

The effects of dough aeration on measured bulk rheology of dough were investigated by preparing doughs with various gas contents and assessing their rheology under large deformation biaxial extension using the SMS Dough Inflation System. Doughs were mixed to various gas contents using a laboratory‐scale mixer, the Tweedy 1, at various mixer headspace pressures. In order to consider the effect of oxidation processes, doughs were mixed in air, in nitrogen and in a controlled oxygen‐nitrogen atmosphere in which the partial pressure of oxygen was kept constant. In the latter two cases a flow rate of gas through the mixer was maintained, while the doughs mixed in air had a static headspace. Dough aeration was quantified using density measurements. The dough rheology tests were performed under two different modes: constant volumetric air flow rate; and constant strain rate at two levels, 0.1 and 0.05 s⁻¹. Analysis of the stress–strain data of an inflating dough bubble using an exponential model enabled the strain hardening index, failure strain and failure stress to be determined. The strain hardening index, failure strain and failure stress decreased with gas content, indicating that gas bubbles in dough disrupt the integrity of dough structure. The faster strain rate tended to give higher values of all parameters and to be more discriminating, while testing at a constant volumetric air flow rate gave lower values. Doughs mixed under a constant partial pressure of oxygen resulted in the strain hardening index being minimally affected by the gas content, although failure strain and failure stress decreased with increasing gas content in the dough. The flow of gas through the mixer appeared to affect dough aeration and rheology, and the rate of work input was found to increase with increasing mixer headspace pressures. These suggest that dough aeration not only affects the rheology of static dough through the physical presence of gas bubbles following mixing, it also affects the development of its rheological properties within the mixer, through the physical presence of the bubbles affecting the rate of work input that develops the doughs, and also through the turnover of air that supplies oxygen to facilitate this development. Copyright © 2005 Society of Chemical Industry     

Improvers and functional ingredients in whole wheat bread: A review of their effects on dough properties and bread quality

BackgroundDespite the associated health benefits of whole grains, consumption of whole grain products remains far below recommended levels. Whole wheat bread is often associated with many distinctive attributes such as low loaf volume, firm and gritty texture, dark and rough crust and crumb appearance, bitter flavor, and reduced shelf-life. There is a need to improve its quality and sensory characteristics so as to increase consumer appeal and, ultimately, increase the intake of whole wheat bread. The inclusion of various ingredients improves dough and bread properties.Scope and approachThis review examines the effects of enzymes, emulsifiers, hydrocolloids, and oxidants on the properties of whole wheat bread and dough, with particular attention to effects on loaf volume and hardness. Wheat gluten and other plant materials are also discussed. Gaps in the research into whole wheat bread are identified, and future research needs are recommended.Key findings and conclusionsXylanase reduces the water absorption of whole wheat flour and increases loaf volume and crumb softness by hydrolyzing ararbinoxylans. α-amylase can be beneficial under certain conditions. Phytase may activate endogenous α-amylase. G4-amylase is promising but needs validation by further research on its effect on loaf volume, crumb hardness, and staling. Vital wheat gluten overcomes many of the challenges of whole wheat bread production and is found in the majority of commercial whole wheat breads. Emulsifiers DATEM and SSL can improve the volume, texture and staling profile of whole wheat bread. Several types of improvers are generally needed in combination to provide the greatest improvement to whole wheat dough and bread.     

Potential of grape byproducts as functional ingredients in baked goods and pasta

Wine making industry generates high quantities of valuable byproducts that can be used to enhance foods in order to diminish the environmental impact and to obtain more economic benefits. Grape byproducts are rich in phenolic compounds and dietary fiber, which make them suitable to improve the nutritional value of bakery, pastry, and pasta products. The viscoelastic behavior of dough and the textural and the sensory characteristics of baked goods and pasta containing grape byproducts depend on the addition level and particle size. Thus, an optimal dose of a finer grape byproducts flour must be found in order to minimize the negative effects such as low loaf volume and undesirable sensory and textural characteristics they may have on the final product quality. In the same time, an enrichment of the nutritional and functional value of the product by increasing the fiber and antioxidant compounds contents is desired. The aim of this review was to summarize the effects of the chemical components of grape byproducts on the nutritional, functional, rheological, textural, physical, and sensory characteristics of the baked goods and pasta. Further researches about the impact of foods enriched with grape byproducts on the human health, about molecular interactions between components, and about the effects of grape pomace compounds on the shelf life of baked goods and pasta are recommended.