Fundamental rheological and textural properties of doughs and breads produced from milled pearled barley flour

Barley has long been known as a good source of fibre and in particular beta-glucan, but increased consumer awareness has meant that this is only now being exploited by food scientists and the food industry. In this study, doughs and breads were produced using pearled barley flour (PBF) in different ratios (30, 50, 70 and 100%) to wheat flour. A 100% wheat flour formulation was used as a control. The flour formulations were evaluated for protein content; the dough rheological properties of the formulations were evaluated using fundamental oscillatory tests and uniaxial extension tests. The baked breads were evaluated for volume, texture, moisture, dietary fibre and beta-glucan. Digital image analysis of the crumb grain was also carried out. Protein analysis revealed that increasing the amount of PBF in the formulation leads to a significant (p < 0.001) decrease in the protein content of the formulation. Starch pasting properties were also affected by an increase in PBF concentration, with an increase in PBF significantly increasing the peak viscosity, breakdown, setback and final viscosity of the starch slurries of the formulations. Extensional rheology revealed that increasing the PBF in the doughs leads to the doughs rupturing at lower extensions and with a lower force. Bread volume between treatments was found to be significantly (p ≤ 0.001) different, with an increase in PBF inclusion leading to smaller loaves. Texture profile analysis of the bread slices showed that breads containing higher ratios of PBF had a significantly harder (p ≤ 0.001) and less cohesive (p ≤ 0.001) crumb. Low levels of PBF (≤50%) did not significantly effect loaf volume or crumb texture, however, and the total dietary fibre and beta-glucan levels of the loaves were significantly increased (p ≤ 0.001) with increasing levels of PBF in the formulation, even at low levels of inclusion.     

Effects of hull-less barley flour and flakes on bread nutritional composition and sensory properties

Barley is a desirable food ingredient, with health benefits provided by a β-glucan fibre fraction. A hull-less barley flour and flakes were incorporated into white and wholegrain wheat bread in quantities usually applied in practice. The breads were evaluated for nutritional composition and sensory properties and compared to standard products as controls. The supplemented breads were high in fibre, zinc and selenium content. It was estimated that a 300-gram daily portion of such breads could meet up to 40% of dietary recommended intakes for selenium and 70–75% of recommended daily values for β-glucan. Regarding sensory quality, the only significant differences (p < 0.05) were higher taste and lower volume in the white supplemented breads and lower crumb elasticity in the white bread made with barley flour. Hull-less barley can substantially contribute to an adequate intake of selenium and β-glucan. In addition, supplemented breads were not found to pose a significant risk, with regard to excessive intakes of heavy elements (Pb, Cd, As).     

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

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

Probabilistic methodology for assessing changes in the level and molecular weight of barley β-glucan during bread baking

The objective of this study was to create a probabilistic model to assess changes in the levels and molecular weight (Mw) of β-glucan during the bread baking process using Monte Carlo simulation techniques. Three different composite flours were formulated by substituting wheat flour (WF) with barley whole meal flour (BWMF), barley straight grade flour (BSGF) or barley fibre rich fraction (BFRF). The β-glucan level in the flour increased significantly (by approximately 10-fold) when barley was substituted for WF. The baking process resulted in approximately a 47–48% reduction in the β-glucan level in the baked bread (base-line model). The base-line model observed ∼25% and 7% reduction in high molecular weight (HMw) and medium molecular weight (MMw), respectively and a subsequent increase in low molecular weight (LMw). The analysis also showed the importance of various steps involved in bread baking, such as mixing time (Mt), fermentation time (Ft) and baking (BGloss), on the level and Mw of β-glucan in baked breads. A parallel experimental validation study provided confidence in model predictions of β-glucan levels. This study aids in optimising the various unit operations involved in the bread baking process to give a final product with increased nutritional qualities.     

Effects of two barley β-glucan isolates on wheat flour dough and bread properties

The effects of wheat flour fortification with two different molecular weight barley β-glucan isolates (1.00 × 10⁵, BG-100 and 2.03 × 10⁵, BG-200) on the rheological properties of dough and bread characteristics, using flours from two wheat cultivars that differ in their breadmaking quality, have been examined. The farinograph water absorption of doughs and the moisture content and water activity of the breads increased with increasing β-glucan content; the β-glucan isolate with the higher molecular weight (BG-200) exerted a greater effect than did BG-100. The addition of β-glucans to the dough formula increased the development time, the stability, the resistance to deformation and the extensibility of the poor breadmaking quality doughs, as well as the specific volumes of the respective breads, exceeding even that of the good breadmaking cultivar. Furthermore, the colour of the bread crumbs got darker and their structure became coarser, whereas the bread crumb firmness decreased with increasing level of β-glucan addition. Generally, the BG-200 was more effective in increasing the specific bread volume and reducing the crumb firmness, especially when used to fortify the poor breadmaking quality flour. The results further indicate a requirement for optimisation of the fortified doughs (level and molecular size of the β-glucan) to maximise bread quality attributes (loaf volume, texture, and staling events).     

Nutritional and functional performance of high β-glucan barley flours in breadmaking: mixed breads versus wheat breads

The ability of high β-glucan barley (HBGB) flour versus regular commercial barley (CB) to make highly nutritious wheat (WT) blended breads meeting functional and sensory standards has been investigated. Mixed breads obtained by 40 % replacement of WT flour by HBGB flours are more nutritious than those replaced by CB flours and much more than regular WT flour breads in terms of elevated levels of dietary fibre fractions (soluble, insoluble, resistant starch and β-glucans), slowly digestible starch subfraction and bioaccessible polyphenols providing higher antiradical activity. WT/CB and WT/HBGB breads can be, respectively, labelled as source of fibre (3 g DF/100 g food) and high-fibre breads (6 g DF/100 g food), according to Nutritional Claims for dietary fibre foods. The consumption of 100 g of WT/HBGB can meet up to almost 50 % the required dietary fibre, providing a β-glucan intake high enough to meet the requirements of the EFSA health claim (3 g/day), contributing a reduced blood cholesterol level. The techno-functional performance of fresh blended breads and the sensory appreciation were in general preserved or even improved.     

Organoleptic and nutritional evaluation of wheat breads supplemented with soybean and barley flour

Supplementations of soy (full fat and defatted) and barley flours to wheat flours at 5, 10, 15 and 20% levels were carried out to test the effects on organoleptic and nutritional evaluation of the supplemented bread. Additions of 15% barley flour, 10% soy flour (full fat and defatted), 15% barley plus full fat soy flour and 15% barley plus defatted soy flour to wheat flour produced acceptable breads. However, substitution of soy (full fat and defatted) and barley flours to wheat flour separately and in combinations at 20% levels did not produce organoleptically acceptable bread. Various nutritional parameters, such as protein, fat, total lysine, protein digestibility (in vitro), sugars, starch digestibility (in vitro), total and available minerals, antinutrients, dietary fibre and β-glucan were determined in supplemented and control bread. Increasing the level of substitution from 5 to 10% of full fat and defatted soy flour to wheat flour significantly (P<0.05) increased protein (from 12.1 to 13.7 and 12.4 to 13.8%), lysine (from 2.74 to 3.02 and 2.76–3.05 mg/100 g protein) and total calcium (from 70.2 to 81.4 and 71.9–81.8 mg/100 g) contents. However, there was also an increase in phytic acid (238–260 and 233–253 mg/100 g), polyphenol (324–331 and 321–329 mg/100 g) and trypsin inhibitor activity (193–204 and 193–198 TIU/g). When barley flour was substituted separately, and in combinations, with full fat and defatted soy flour up to 15%, this significantly increased the contents of protein, total lysine, dietary fibre and β-glucan. It may be concluded that breads supplemented with barley and defatted soy flour, up to a 15% level, are organoleptically and nutritionally acceptable.     

Dietary exposure assessment of β-glucan in a barley and oat based bread

The objective of this study was to develop a β-glucan human exposure assessment model for a barley and a oat based bread and to compare the resulting exposure to the current FDA recommendation for a health promoting effect (3 g β-glucan/day, 0.75 g/portion of β-glucan). Three formulated barley and oat based breads with 30% (S1), 50% (S2) and 70% (S3) substitution of wheat flour were used in the Monte Carlo simulation model to predict human consumption levels. The level of soluble β-glucan was found to reach 0.77 g/portion for some barley and oat based breads with a substitution level of S3. Under normal consumption patterns, consumption of barley based bread can meet up to 50% of the FDA recommended intake with S1, 70% with S2, and 100% with S3, whereas by consuming an oat based bread the FDA recommended intake is met 30% with S1, 50% with S2 and 70% with S3. The model predicted that total cholesterol (TC) lowered with an increase intake of β-glucan content from ?0.27 to ?0.30 mmol/l and ?0.18 to ?0.29 mmol/l from S1 to S3 for barley and oats based bread, respectively. No significant change was noted for the blood glucose level.     

Bread quality by substituting normal and waxy hull-less barley (<Emphasis Type="Italic">Hordeum Vulgare</Emphasis> L.) flours

Substitution of regular and waxy hull-less barley flour was evaluated in pan breads prepared from the blends of barley cvs. Saessal (SSWB) and Saechalssal (SCWB) with wheat flour. Effect of barley type and barley flour level (10, 20, and 30%) was investigated on compositions, dough development, and bread qualities. Compared to 100% wheat flour, increasing barley flour increased ash from 0.36 to 0.67%, and β-glucan from 0.1 to 1.91%. Pasting viscosity exhibited higher peak viscosity, through, and breakdown in barley flour blends, showing higher viscosity in SSWB than SCWB. Optimum water absorption and mixing time were increased in barley-wheat flour blends. Substitution of 10% barley flour had no significant difference from wheat bread in bread volume and crumb firmness statistically (p<0.05). The SSWB showed better bread qualities in terms of bread volume and crumb firmness than SCWB. The β-glucan content was 0.13% in wheat bread, but ranged from 0.45 to 1.05% in barley breads.     

Influence of water and barley β-glucan addition on wheat dough viscoelasticity

The effects of the addition of two barley β-glucan isolates (0.2–1.0% of wheat flour), differing in molecular weight, and water (53–63% in a poor breadmaking wheat flour, cv. Dion, and 58–68% in a good breadmaking wheat flour, cv. Yekora) on the viscoelastic properties of wheat flour doughs were investigated. A response surface model (CCF) was used to evaluate the effects observed on the dynamic and creep-recovery parameters of the dough. The evaluation was done separately for each combination of β-glucan isolate (BG1 of ～10⁵ Da and BG2 of ～2 × 10⁵ Da) and flour type. Besides the contents of β-glucan and water, the molecular size of the polysaccharide and the flour quality were important determinants of the dough’s viscoelastic behavior. Compared to BG1, the higher molecular weight β-glucan (BG2) brought about major changes on all the rheological responses of the fortified doughs. The addition of appropriate levels of β-glucans and water in the poor breadmaking cultivar (Dion) doughs could yield similar viscoelastic responses to those observed by a non-fortified good breadmaking quality flour dough (Yekora).     

Characterisation of dietary fibre components in rye products

In this study, dietary fibre (DF) was characterised in rye products from a local supermarket. Soft breads generally had lower DF contents (8–18%) than had crisp breads (13–20%) due to high inclusion of wheat flour. For some products, the labelled DF values contained fructan, but others did not. However, for most products, the DF values analysed exceeded those declared. Arabinoxylan (AX) and fructan were generally the main DF components in the products, followed by cellulose and resistant starch, β-glucan, Klason lignin and arabinogalactan. In the soft breads, cellulose and resistant starch concentrations were relatively high, due to significant formation of resistant starch. During bread manufacturing, the molecular weight of β-glucan was highly degraded, while that of AX was more resistant. Extruded products had the highest β-glucan extractability and the extracted β-glucan retained its molecular weight most, which may be of nutritional significance. In rye milling fractions, about 50% of the fructan content analysed had a degree of polymerisation below 10, i.e. it comprised oligosaccharides. The crisp breads produced without yeast had the highest DF and fructan contents and the highest proportion of low-molecular weight fructan. These results indicate that, during bread-making, the low-molecular weight fraction of fructan was most available for degradation by yeast or by endogenous enzymes present in the ingredients.     

Effects of flour from different barley varieties on barley sour dough bread

Twenty flours from 16 different barley varieties cultivated in 1990 and 1992, and a Swedish reference flour, were fermented by Lactobacillus plantarum A1 to sour doughs. Barley breads (40% barley/60% wheat flour) from each flour type were baked with and without an admixture of barley sour dough in order to investigate how the sour dough admixture would affect the baking properties. A trained panel carried out sensory evaluation by conventional profiling on breads made from three of the barley varieties and the Swedish reference flour, made with and without sour dough admixture.

The barley varieties influenced both the sour dough properties and the properties of the barley bread. The pH of bread with sour dough ranged from 4.6 to 4.8 as compared to 5.4 to 5.6 in bread without sour dough. The acidity of the breads with sour dough ranged from 4.1 to 5.0 ml NaOH/ 10 g bread crumb as compared to 2.4 to 3.6 in breads without sour dough. In 14 of the twenty bread types an addition of sour dough lowered the bread volume. Breads with a sour dough admixture scored higher for total taste and acidulous taste than breads without sour dough. The β-glucan content of the flours had no significant influence on the sour dough or the sensory characteristics of the bread, except for the breadcrumb colour.     

Effect of Microwave Radiation Pretreatment of Rice Flour on Gluten-Free Breadmaking and Molecular Size of β-Glucans in the Fortified Breads

Cereal β-glucan concentrates can be used in gluten-free breads to improve dough handling properties and quality of final products as well as to enhance their nutritional value; however, the presence of endogenous β-glucanases in rice flour, in combination with prolonged mixing, fermentation, and proofing time, can cause a substantial reduction in β-glucan molecular weight, affecting detrimentally their efficacy for bioactivity. In this study, microwave (MIWA) heating was applied to the rice flours before breadmaking at different flour water contents (13–25%) and treatment times (0-4 min) to reduce β-glucanase activity. Gluten-free breads made from the MIWA-treated rice flours were fortified with oat β-glucan concentrate to enhance their nutritional profile. The molecular weight of added β-glucan in the final products increased with increasing both flour water content and time of MIWA treatment, reflecting the magnitude of residual β-glucanase activity in the flour. Pretreatment with MIWA radiation for 4 min of the rice flour tempered at 25% moisture resulted in negligible residual β-glucanase activity and preserved to a great extent the molecular weight of β-glucans in the enriched breads. End-product quality was not affected by flour MIWA pretreatment, and even a slightly higher loaf specific volume was noted for breads made from the MIWA-treated flours (4 min MIWA at 25% moisture content) compared to that of untreated flour. These findings can contribute to the improvement of nutritional value of rice-based gluten-free breads for celiac consumers as well as of any β-glucan-containing yeast-leavened bakery product without altering its sensorial attributes. Additional studies are still required for further evaluation of the effect of more intense microwave treatment on rice flour and its application on breadmaking.     

Effect of β-Glucan Concentrate on the Water Uptake,Rheological and Textural Properties of Wheat Flour Dough

The effects of the addition of β-glucan concentrate (2.5–10 g/100 g flour) and water (58–70 mL/100 g flour) on the rheological and textural properties of wheat flour doughs were studied. Various empirical (farinograph, extensograph, dough inflation, and dough stickiness) and fundamental rheological tests (oscillatory and creep-recovery) were employed to investigate composite dough structure and an attempt was made to correlate the data obtained from different instrumental measurements. The water absorption increased with the addition of β-glucan concentrate into wheat flour. An increase in mixing time and stability were recorded upon addition of β-glucan concentrate (≤ 5 g/100 g flour), and the extensibility decreased at similar condition. The composite dough exhibited predominating solid-like behavior. The mechanical strength, dough stickiness, the peak dough inflation pressure decreased with increasing water content but those parameters increased with β-glucan concentrate incorporation within the studied concentration range. Creep-recovery tests for 5 g β-glucan concentrate/100 g flour doughs recorded less resistance to deformation with an increase in water level and data were well described by the Burger model. Thermal scanning of doughs revealed that the protein denaturation peak was significantly influenced by water content, and the values were ranged between 110 and 124°C. Significant relationships between empirical and fundamental rheological testing methods were found.     

Effects of enzymes in fibre-enriched baking

The aim of the present study was to improve the quality of fibre-enriched wheat breads by enzymic treatment of the fibre fraction. The suitability of different enzymes in fibre-enriched baking and their effects on the dietary fibre content and the ratio of insoluble: soluble fibre content of the breads were studied. The enzyme preparations used were a hemicellulolytic culture filtrate of Trichoderma reesei, a specific (pI 9) xylanase of T reesei and Fermizyme, an α-amylase preparation containing a standardised level of hemicellulase activity. Rye bran was extracted in water (10% (w/w) suspension) to determine the solubilities of the β-glucans and pentosans. Addition of T reesei culture filtrate significantly increased the amount of extractable pentosan obtained from nonautoclaved rye bran. Rye bran supplementation (5%) of wheat flour increased the farinograph absorption and dough development time, but had little or no effect on stability and softening of the dough. The added enzymes decreased dough stability and increased softening. Addition of enzymes caused significant differences in the stickiness of the wheat doughs both with (P<0·003) and without (P<0·001) rye bran. Fermizyme significantly increased the stickiness of wheat doughs both with and without rye bran. The baking results of the fibre-enriched breads were improved by the added enzymes. Addition of T reesei culture filtrate increased the specific volume of the wheat breads both with and without rye bran by almost 20%. Enzyme mixtures were more efficient than individual xylanase in softening the bread crumb and reducing the staling rate of wheat breads both with and without rye bran. Incorporation of enzymes reduced the total dietary fibre content of the breads, but at least doubled the amount of soluble pentosan. The proportions of fluorescent cell walls in the breads were detected by microscopical image analysis. Enzyme addition caused the surface area of insoluble cell walls originating from wheat flours to decrease, suggesting that the enzymes exert more effects on wheat endorsperm cell walls than on bran particles. © 1998 SCI.     

The behaviour and susceptibility to degradation of high and low molecular weight barley β-glucan in wheat bread during baking and in vitro digestion

The behaviour and susceptibility to degradation of a high molecular weight (HMW) and low molecular weight (LMW) barley β-glucan in white bread during manufacture and in vitro digestion were investigated. The incorporation of both HMW and LMW barley β-glucan resulted in stiffer dough, lowered loaf volume and height compared to the control. The HMW barley β-glucan caused the greatest loss of dough and bread quality. Breads with HMW and LMW barley β-glucan exhibited attenuated reducing sugars release (RSR) over a 300 min in vitro digestion compared to the control, with generally no difference between the breads. HMW barley β-glucan was degraded during bread manufacture; however, degradation of the LMW barley β-glucan was not apparent. An in vitro digestion did not result in any further degradation of the molecular weight (MW) of either barley β-glucan.     

Barley β-glucan is effective as a hypocholesterolaemic ingredient in foods

Barley contains high levels of soluble dietary fibre, including mixed linked 1→3, 1→4β-D -glucans (β-glucan). An extract of β-glucan from waxy, hulless barley containing 56% total dietary fibre (TDF) was incorporated into flour tortillas, cornstarch pudding and apple granola bars to provide 2 g soluble fibre as β-glucan per serving. The foods were tested for objective functional properties. Flour tortillas with β-glucan were incorporated into rat diets and compared to diets containing an equivalent amount of cellulose, to test the fibre effect on growth and lipid metabolism parameters. Rats fed β-glucan tortillas had lower feed consumption and body weight (P<0·05) compared to those fed the cellulose tortillas, although feed/gain ratios were not different (P>0·05). Plasma LDL-cholesterol of rats fed β-glucan was lower (P<0·05) than cellulose-fed controls, although total cholesterol and triglycerides did not differ (P>0·05). Rats fed β-glucan tortillas had higher (P<0·05) faecal fat excretion, suggesting impairment of intestinal fat absorption. Liver composition data showed lower (P<0·05) levels of total lipid and cholesterol in β-glucan-fed rats. The results suggest that the barley β-glucan concentrate has potential as a food ingredient to provide supplemental soluble fibre which may be beneficial in reducing plasma LDL-cholesterol in humans. © 1998 SCI.     

Utilisation Glucagel® in the β-glucan enrichment of breads: A physicochemical and nutritional evaluation

Traditional white bread is a poor source of dietary fibre, containing typically less than 2.5%. A demand exists for the development of high fibre white breads of nutritional benefit to the consumer. This paper explores the possibility of using Glucagel^®, a β-glucan isolate, from barley (Hordeum vulgare) to raise the nutritional status of bread products. Glucagel^® was incorporated into breads at 2.5 and 5% inclusion rates. Negative changes were observed in dough quality and baking performance with the addition of Glucagel^®. In vitro analysis of the bread samples revealed a significant decrease in reducing sugar release over a 300 m digestion in breads supplemented with 5% Glucagelsample. However, incorporation of Glucagelincrease starch availability for digestion. This has implications in the reduction of hyperglycaemia and hyperinsulinaemia, with reference to the control of diabetes and development of degenerative diseases.     

Utilization of Transglutaminase to Increase the Level of Barley and Soy Flour Incorporation in Wheat Flour Breads

ABSTRACT: This study investigated the possibility of incorporating barley or soy flour into wheat flour using transglutaminase (TG)-catalyzed cross-linking, without deterioration in bread quality. A Farinograph and texture analyzer were used to examine mixing properties and extensibility of doughs, respectively. Addition of increasing levels of barley/soy flour (with and without TG) increased Farinograph water absorption in the soft and hard wheat cultivars studied. Dough resistance increased and extensibility decreased with TG treatment. TG showed great promise in processing of bread supplemented with barley flour, even at a very low level (0.25%, wt/ wt), but did not notably improve the quality of soy flour-supplemented breads.     

Physicochemical characteristics and in vitro bile acid binding and starch digestion of β-glucans extracted from different varieties of Jeju barley

Physicochemical properties of six different varieties of barley and their β-glucans were evaluated along with in vitro bile acid binding and starch digestibility for health beneficial effects. β-Glucan concentrations in less-hulled, beer, black, waxy-naked, naked, and blue barley were 3.44, 3.46, 6.08, 6.75, 6.45, and 5.91%, respectively. Viscosity of waxy-naked barley flour was the highest. While the yield of β-glucan from waxy-naked barley after extraction was 95.49%, less-hulled barley was 70.09%. As the increase of β-glucan purification, in vitro bile acid binding was increased when compared with cholestyramine and cellulose. In vitro starch digestibility of barley flour and the mixture of potato starch with β-glucan were increased by heat and β-glucan concentration. Estimated glycemic index (GI) calculated based on in vitro starch digestibility was decreased by increasing β-glucan. These results suggest that the physicochemical properties of barley were dependent on the variety of barley and especially β-glucan was involved.