Wheat Bread Quality as Influenced by the Substitution of Waxy and Regular Barley Flours in Their Native and Extruded Forms

The substitution of wheat flour with barley flour (i.e. native or pretreated/extruded) reduced the loaf volume. Depending on the barley variety and flour pretreatments, the colour and firmness/texture of the bread loaves were altered. Amongst the barley breads prepared from native flours (at 15% barley flour substitution level), Phoenix had higher loaf volume and lower crumb firmness than Candle. However, amongst the barley breads prepared from extruded flours, CDC-Candle had higher loaf volume and lower crumb firmness than Phoenix. The lower loaf volume and firmer crumb texture of barley breads as compared with wheat bread may be attributed to gluten dilution. Also, the physicochemical properties of barley flour components, especially that of β-glucan, can affect bread volume and texture. β-glucan in barley flour, when added to wheat flour during bread making, could tightly bind to appreciable amounts of water in the dough, suppressing the availability of water for the development of the gluten network. An underdeveloped gluten network can lead to reduced loaf volume and increased bread firmness. Furthermore, in yeast leavened bread systems, in addition to CO₂, steam is an important leavening agent. Due to its high affinity for water, β-glucan could suppress the amount of steam generated, resulting in reduced loaf volume and greater firmness. In the present study, breads made with 15% HTHM CDC-Candle flour had highly acceptable properties (loaf volume, firmness and colour) and it indicated that the use of extruded barley flours would be an effective way to increase the dietary fibre content of barley breads.     

The potential of naked barley sourdough to improve the quality and dietary fibre content of barley enriched wheat bread

The possibility of using naked barley for food products is gaining popularity due to its dietary fibre content, especially β-glucans. The technological process (dough preparation, fermentation and baking) influences bread quality but also may contribute to degradation or preservation of valuable grain components. The aim of the study was to investigate the effects of different wholemeal barley flour share and bread production method on the quality of bread and non-starch polysaccharides content and solubility.Barley enriched bread contained more both soluble and insoluble dietary fibre and β-glucans, products of 40% barley share contained 67% more total dietary fibre and 160% more β-glucans than control. However, barley incorporation decreased the amount of soluble arabinoxylans. High barley contents contributed to the breads’ volume reduction by 14% and change in their crumb and crust colour. However, barley enriched breads gained higher ratings of taste than wheat bread. Barley sourdough fermentation improved breads’ volume, colour and sensory properties. Sourdough fermentation also resulted in higher concentration of dietary fibre, arabinoxylans and β-glucans. The beneficial effect of barley addition to wheat bread may be successfully enhanced by using barley wholemeal sourdough fermentation.     

Development of β-glucan enriched wheat bread using soluble oat fiber

Soluble oat fiber (SOF) containing 70% oat β-glucan was incorporated into wheat bread by replacing 10, 12, and 14% of flour in wheat bread formulas. At each level of SOF, bread was made at the farinograph water content defined by the amount of water required to develop a dough consistency of 500 Brabender Units in farinograph tests, and 10 and 20% extra water above the farinograph water content. At the farinograph water content, bread formulated at each level of SOF exhibited lower specific volume and porosity, darker color, higher hardness, and lower springiness and cohesiveness than the control white bread. These negative effects were effectively counteracted by optimizing the water content in bread formulas. For the three levels of bran addition, when the water content was increased by 20% above the farinograph water content, the obtained loaves exhibited similar loaf volume, microstructure, textural properties, and crumb porosity to the control white bread. A serving (28 g) of the developed bread contained respectively 0.95, 1.12, and 1.28 g of β-glucan, which substantially exceed the minimum standard for approved health claims.     

Effect of technological process on the nutritional quality of naked barley enriched rye bread

Naked barley products used in bread making gain popularity as a source of both soluble and insoluble fractions of dietary fibre, especially β-glucans. The aim of the study was to investigate the effects of different naked barley flour share in rye bread formulations and dough preparation methods (Single-phase and Detmold sourdough) on non-starch polysaccharides content and solubility and antioxidant properties of products at different processing stage. Naked barley incorporation to rye contributed to the increase in dietary fibre content with higher soluble fraction share, highly enriched products in β-glucan and increased antioxidant activity of products. It also contains high amounts of arabinoxylans, but less soluble than those from rye. A Single Phase method of rye bread production resulted in higher β-glucan concentration in products and their antioxidant activity, compared to Detmold method products. The nutritional quality of bread is highly influenced by the process parameters.     

Wholemeal wheat bread: A comparison of different breadmaking processes and fungal phytase addition

The effect of different breadmaking processes (conventional, frozen dough, frozen partially baked bread) and the effect of the storage period on the technological quality of fresh wholemeal wheat breads are investigated. In addition, the impact of the exogenous fungal phytase on the phytate content was also determined. Results showed that breadmaking technology significantly affected the quality parameters of wholemeal breads (specific volume, moisture content, crumb and crust colour, crumb texture profile analysis and crust flaking) and frozen storage affected to a different extent the quality of the loaves obtained from partially baked breads and those obtained from frozen dough, particularly crust flaking. Freezing and frozen storage of wholemeal bread in the presence of fungal phytase decreased significantly the phytate content in whole wheat breads. The combination of fungal phytase addition, breadmaking process and frozen storage could be advisable for overcoming the detrimental effect of bran on the mineral bioavailability.     

Sourdough fermentation of wholemeal wheat bread increases solubility of arabinoxylan and protein and decreases postprandial glucose and insulin responses

Glycemic responses to most of the conventional breads are high, including breads made of wholemeal flour. Baking technology is known to affect these responses. The aim of the present study was to investigate effects of xylanase enzyme treatment and sourdough fermentation in wholemeal wheat bread baking on postprandial glucose and insulin responses and on in vitro protein digestibility. The wheat breads were made of 100% flour from peeled kernels by a straight dough or sourdough fermentation method, and with or without using xylanase during mixing of dough. Standard white wheat bread was used as a reference. All test bread portions contained 50 g available carbohydrate and were served in random order to eleven insulin resistant subjects. Blood samples for measuring glucose and insulin concentrations were drawn over 4 h. The sourdough wholemeal wheat bread resulted in the lowest postprandial glucose and insulin responses among the four tested breads (treatment × time; p = 0.000 and p = 0.022, respectively). There were differences in solubility and depolymerisation of protein and arabinoxylan among the breads but these did not fully explain the in vivo findings. In conclusion, the health effects of wholemeal wheat bread can be further improved by using sourdough process in breadmaking.     

The combined use of hull-less barley flour and xylanase as a strategy for wheat/hull-less barley flour breads with increased arabinoxylan and (1→3,1→4)-β-D-glucan levels

Bread-making with a composite flour (CF) consisting of 60% wheat flour (WF) and 40% hull-less barley flour, increased the total and soluble (1→3,1→4)-β-D-glucan and total arabinoxylan (AX) contents of dough and bread samples, but decreased the specific bread loaf volume. A xylanase insensitive to inhibition by Triticum aestivum L. xylanase inhibitor (TAXI) and xylanase inhibiting protein (XIP), increased loaf volume by 8.8 and 20.1% for WF and CF breads, respectively. Xylanase addition not only markedly improved loaf volume of CF bread, but also increased the soluble AX content of the WF and CF dough and bread samples because of conversion of water-unextractable AX into soluble AX. The xylanase had no impact on the extractability and molecular weight of (1→3,1→4)-β-D-glucan, but (1→3,1→4)-β-D-glucan was degraded during bread-making probably because of endogenous β-glucanase activity. Taken together, the results clearly show that the combined use of hull-less barley flour and a xylanase active during bread making, lead to palatable breads with high total and soluble AX and (1→3,1→4)-β-D-glucan contents. The sum of total AX and (1→3,1→4)-β-D-glucan was 1.70% for WF bread and 3.06% for CF bread, while the sum of soluble AX and (1→3,1→4)-β-D-glucan was 0.49 and 1.41% for control WF and CF xylanase supplemented breads, respectively.     

Scouting the application of sourdough to frozen dough bread technology

The use of sourdough, even in combination with cryoprotectant (skim milk, sucrose and trehalose), conventional additives (guar gum, diacetyl tartaric acid esters of monoglycerides, ascorbic acid), honey or fructose and glucose, in frozen dough technology was investigated. After frozen storage, the leavening performance of doughs, and the hardness and texture of breads were compared to those of an unfrozen dough, and to those of a conventional frozen dough. All frozen doughs showed a longer fermentation time and a lower volume increase, with respect to unfrozen dough. When sourdough was combined with cryoprotectant, honey or both, the leavening performance improved compared to the use of sourdough alone. Compared to the conventional frozen dough, higher leavening performance was reached combining sourdough with cryoprotectant alone or together with honey. Sourdough combined with honey, fructose and glucose, honey and cryoprotectant, or conventional additives decreased bread hardness compared to the unfrozen dough bread and to the conventional frozen dough bread. Independently from the use of sourdough, conventional additives allowed to reach a specific volume not significantly different from that of unfrozen dough bread, and breads containing honey were characterized by low values of hardness and by high values of red index.     

Molecular weight distribution and content of water-extractable β-glucan in rye crisp bread

Rye crisp doughs and breads were made from three rye flours with different falling numbers (i.e. different enzyme activity), with or without oat bran rich in β-glucan (OBG) added, and with different fermentation times. The aim of the study was to investigate the effect of endogenous enzymes in the flour on molecular weight and content of water-extractable β-glucan in the doughs and breads. The molecular weight distribution of β-glucan was unimodal for the flours, with a calcofluor average molecular weight of about 90×10⁴ g/mol for the rye flours, and 150×10⁴ g/mol for rye flours with added OBG. The molecular weight decreased with increasing fermentation time for all doughs, but was almost unchanged during oven-baking. The calcofluor average molecular weight was highest in doughs and breads made of flour with highest falling number (i.e. lowest enzyme activity), indicating that the endogenous enzymes in the flour were responsible for the breakdown of β-glucan. During fermentation, water-extractable β-glucan was released from the insoluble matrix, probably by the endogenous enzymes in the flour. When the molecular weight of the water-extractable β-glucan decreased, they probably associated with each other or with other components in the dough to form unextractable complexes. The content of water-extractable β-glucan did not change during oven-baking.     

Effect of barley flour addition on the physico-chemical properties of dough and structure of bread

The effects of different percentages of barley flour (i.e. 0–25%) in wheat flours on the physico-chemical properties and structure of dough and bread were investigated. As the percentage of barley flour in mixed flour was increased, its protein and gluten contents decreased whereas the ash content and enzyme activity increased. The rheological characteristics of the four dough mixes were studied using Farinograph, Extensograph and Alveograph. The water absorption (p < 0.01) and stability (p < 0.05) decreased significantly as the percentage of barley flour increased, while no changes were observed in the extensibility and maximum heights. Significant differences were observed in the structural and physical properties as well as in the image analysis of breads. With the increase in the percentage of barley flour, the crumb apparent density decreased (p < 0.1) whereas the porosity (i.e., fraction to total volume) increased (p < 0.1). Overall, the shape and pore structure at 10% barley flour (W90B10) were similar to the pure wheat flour bread, while addition at 15 and 25% of barley flour (W85B15 and W75B25) showed more non-uniform and larger pores.     

Phytate negatively influences wheat dough and bread characteristics by interfering with cross-linking of glutenin molecules

The influence of added phytate on dough properties and bread baking quality was studied to determine the role of phytate in the impaired functional properties of whole grain wheat flour for baking bread. Phytate addition to refined flour at a 1% level substantially increased mixograph mixing time, generally increased mixograph water absorption, and reduced the SDS-unextractable protein content of dough before and after fermentation as well as the loaf volume of bread. The added phytate also shifted unextractable glutenins toward a lower molecular weight form and increased the iron-chelating activity of dough. It appears that phytate negatively affects gluten development and loaf volume by chelating iron and/or binding glutenins, and consequently interfering with the oxidative cross-linking of glutenin molecules during dough mixing. Phytate could be at least partially responsible for the weak gluten network and decreased loaf volume of whole wheat flour bread as compared to refined flour bread.     

Improving the quality of nutrient-rich Teff (Eragrostis tef) breads by combination of enzymes in straight dough and sourdough breadmaking

The growing interest in the benefits of wholegrain products has resulted in the development of baked products incorporating less utilised and ancient grains such as, millet, quinoa, sorghum and teff. However, addition of wholegrains can have detrimental effects on textural and sensory bread product qualities.Enzymes can be utilised to improve breadmaking performance of wholegrain flours, which do not possess the same visco-elastic properties as refined wheat flour, in order to produce a healthy and consumer acceptable cereal product.The effects of Teff grain on dough and bread quality, selected nutritional properties and the impact of enzymes on physical, textural and sensory properties of straight dough and sourdough Teff breads were investigated.Teff breads were prepared with the replacement of white wheat flour with Teff flour at various levels (0%, 10%, 20%, and 30%) using straight dough and sourdough breadmaking. Different combinations of enzymes, including xylanase and amylase (X + A), amylase and glucose oxidase (A + GO), glucose oxidase and xylanase (GO + X), lipase and amylase (L + A) were used to improve the quality of the highest level Teff breads. A number of physical, textural and sensory properties of the finished products were studied. The nutritional value of breads was determined by measuring chemical composition for iron, total antioxidant capacity, protein, fibre and fat. The obtained results were used to estimates intakes of nutrients and to compare them with DRIs.The incorporation of Teff significantly (P < 0.05) improved dietary iron levels as 30% Teff breads contained more than double the amount of iron when compared to corresponding wheat bread (6 mg/100 g v 2 mg/100 g). Addition of Teff also significantly (P < 0.05) improved total antioxidant capacity from 1.4 mM TEAC/100 g to 2.4 mM TEAC/100 g. It was estimated that an average daily allowance of 200 g of Teff enriched bread would contribute to DRIs in the range of 42-81% for iron in females, 72-138% for iron in males; 38-39% for protein in males, 46-48% for protein in females; and 47-50% of fibre in adults.The major challenge was encountered in producing the highest level of Teff bread with good textural and sensory attributes. Increasing the level of Teff significantly (P < 0.05) increased dough development time, degree of softening, crumb firmness and bitter flavour whilst decreasing the dough stability, specific loaf volume and overall acceptability of the bread. Teff breads produced with the addition of enzyme combinations showed significant improvements (P < 0.05) in terms of loaf volume, crumb firmness, crumb structure, flavour and overall acceptability in both straight dough and sourdough breadmaking.     

Influence of wheat variety and dough preparation on FODMAP content in yeast-leavened wheat breads

FODMAPs are fermentable oligo-, di, and monosaccharides and polyols, which can have adverse effects on human health. Especially in individuals with gastrointestinal disorders such as irritable bowel syndrome, ingestion of FODMAPs may trigger or aggravate symptoms like abdominal pain, bloating, or diarrhea. Our objectives were to investigate the FODMAP content in the flour of 21 wheat varieties and in their 42 yeast-leavened breads prepared with a short (110 min) or a long dough fermentation (24 h), the latter according to a typical baker's recipe. Fructan, glucose, fructose and excess fructose were measured using enzymatic kits. On average, the breads of both dough fermentations had a FODMAP content reduced by > 65% compared to that of the whole grain wheat flour. Average FODMAP content of both dough fermentations was 0.22 g per 100 g fresh bread. FODMAP content tended to be lower in the long compared to the short dough fermentation, however, the difference was not statistically significant. We also found that the 21 wheat varieties differed up to five times in their potential to form FODMAPs in bread. In conclusion, the choice of a low fructan wheat variety coupled with long dough fermentation with sourdough and yeast is best to minimize FODMAPs in breads.     

Oat malt as a baking ingredient – A comparative study of the impact of oat,barley and wheat malts on bread and dough properties

Oat malt is a nutritionally rich ingredient mainly used in a small number of speciality products. The aim of this study was to evaluate the suitability of oat malt in wheat baking. The effect of oat malt on bread and dough properties at levels ranging from 0.5% to 5% was studied and compared with barley and wheat malts. The addition of all malts increased loaf specific volumes. Barley and wheat malts at levels above 2.5% led to a sticky and coarse crumb, but the effect of oat malt on the crumb grain was negligible. Rheological characterisation could not explain the superior baking performance of oat malt, as it increased extensibility and decreased resistance extensively indicating weakening of the extensional properties of the gluten network. The high lipolytic activity may have compensated for the loss of dough strength by improving the surface properties of gas cells. The results show that oat malt can be used in wheat baking to improve the loaf volume and nutritional quality without the detrimental effects associated with the excess amylolytic activity of barley and wheat malts.     

Understanding the role of oat β-glucan in oat-based dough systems

B-glucan is one of the components that differentiate oats from other cereals and that contribute to the health-related value of oats. However, so far oats cannot easily be applied in bread-like products without loss of product quality. Here we have studied how the content and viscosity of oat β-glucan affect the technological properties of oat dough in both a gluten-free and a gluten-containing system. In both systems, increasing the β-glucan concentration resulted in an increase of dough stiffness and in a reduction of dough extensibility. β-glucan negatively impacted the elastic properties that additional wheat gluten conferred to oat dough. This effect was smaller for medium-viscosity β-glucan than for high-viscosity β-glucan. Interestingly, dough made from low β-glucan flour (<2%) had increased gas retention capacity. Overall, the impact of β-glucan on the properties of oat dough systems was governed by concentration and viscosity, with or without additional wheat gluten. Our findings indicate that β-glucan is a key component that determines the rheology of oat-based dough systems and, with that, the technological functionality of oat in dough systems.     

Dough rheology and bread quality of wheat-chickpea flour blends

In this study, partial substitution of wheat flour with chickpea flour at the levels of 10, 20 and 30% was carried out to study their rheological and baking performance. Chickpea flour addition increased the water absorption and dough development time (p < 0.05), while, the extensibility of dough and the resistance to deformation were reduced. Regarding dough stability, it appears that 10% chickpea exhibited higher stability and resistance to mechanical mixing values than the control, while it decreased as the substitute level increases from 20% to 30%. The dough surface of the wheat dough and the blend with 10% was classified as “normal”, however the blend with 20% and 30% produced “sticky” dough surface. The presence of chickpea flour in dough affected bread quality in terms of volume, internal structure and texture. The color of crust and crumb got progressively darker as the level of chickpea flour substitution increased. While the substitution of wheat flour with 10% chickpea flour gave loaves as similar as control.     

Suitability of tef varieties in mixed wheat flour bread matrices: A physico-chemical and nutritional approach

Wheat flour replacement from 0 to 40% by single tef flours from three Ethiopian varieties DZ-01-99 (brown grain tef), DZ-Cr-37 (white grain tef) and DZ-Cr-387 (Quncho, white grain tef) yielded a technologically viable ciabatta type composite bread with acceptable sensory properties and enhanced nutritional value, as compared to 100% refined wheat flour. Incorporation of tef flour from 30% to 40% imparted discreet negative effects in terms of decreased loaf volume and crumb resilience, and increase of crumb hardness in brown tef blended breads. Increment of crumb hardness on aging was in general much lower in tef blended breads compared to wheat bread counterparts, revealing slower firming kinetics, especially for brown tef blended breads. Blended breads with 40% white tef exhibited similar extent and variable rate of retrogradation kinetics along storage, while brown tef-blended breads retrograded slower but in higher extent than control wheat flour breads. Breads that contains 40% tef grain flour were found to contain five folds (DZ-01-99, DZ-Cr-387) to 10 folds (DZ-Cr-37) Fe, three folds Mn, twice Cu, Zn and Mg, and 1.5 times Ca, K, and P contents as compared to the contents found in 100% refined wheat grain flour breads. In addition, suitable dietary trends for lower rapidly digestible starch and starch digestion rate index were met from tef grain flour fortified breads.     

Effect of physicochemical and empirical rheological wheat flour properties on quality parameters of bread made from pre-fermented frozen dough

The objective of this study was to examine the influence of flour quality on the properties of bread made from pre-fermented frozen dough. The physicochemical parameters of 8 different wheat flours were determined, especially the protein quality was analysed in detail by a RP-HPLC procedure. A standardized baking experiment was performed with frozen storage periods from 1 to 168 days. Baked bread was characterised for specific loaf volume, crumb firmness and crumb elasticity. The results were compared to none frozen control breads. Duration of frozen storage significantly affected specific loaf volume and crumb firmness. The reduction of specific loaf volume was different among the used flours and its behaviour and intensity was highly influenced by flour properties. For control breads wet gluten, flourgraph E7 maximum resistance and RVA peak viscosity were positively correlated with specific loaf volume. However, after 1–28 days of frozen storage, wet gluten content was not significantly influencing specific loaf volume, while other parameters were still significantly correlated with the final bread properties. After 168 days of frozen storage all breads showed low volume and high crumb firmness, thus no significant correlations between flour properties and bread quality were found. Findings suggest that flours with strong gluten networks, which show high resistance to extension, are most suitable for frozen dough production. Furthermore, starch pasting characteristics were also affecting bread quality in pre-fermented frozen dough.     

Effect of hydrothermaled bran on physicochemical, rheological and microstructural characteristics of Sangak bread

Increased consumption of whole grain products has been associated with decreased risk of health problems such as cardiovascular disease, diabetes and obesity. Phytate however, has always been a matter of concern, since it chelates minerals such as iron. Sangak is very popular Iranian flat bread invented five hundred years ago, made from 95% extraction flour. The bread is fermented but usually fermentation is not able to remove all phytate from the dough. In this study flours were first debranned; resulting bran was subjected to a hydrothermal process. The hydrothermaled (HT) brans were then incorporated in the Sangak flour. In the next step, physicochemical, rheological and microstructural characteristics of Sangak flour and dough prepared from two Iranian wheat varieties, Tajan and Back Cross of Roshan were investigated. Results indicated a reduction in phytate up to 55% in the samples. The resulting dough containing HT bran showed a higher development time and valorimetric value and was more stable than doughs made with normal bran. Dough made with HT bran showed a kind of protein matrix in which proteins and starch granules are oriented in a more non-ordered structure.     

Wheat Bread Quality as Influenced by the Substitution of Waxy and Regular Barley Flours in Their Native and Cooked Forms

The substitution of wheat flour with barley flours altered the bread loaf volume, colour and bread crumb firmness. These changes were found to be dependent on the barley cultivar, substitution level and flour treatment. In native form, Phoenix barley flour at 15% substitution produced breads with bigger loaf volume and softer crumb than Candle barley flour. However, when the barley flours were heat-treated (pan-cooked in excess water and then dried) before substitution, Candle barley flour produced better quality breads in terms of loaf volume, crumb firmness and crust colour than the Phoenix counterparts. The baking functionality of Candle flour was markedly improved when added after heat treatment.