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.     

Crust and crumb characteristics of gluten free breads

Gluten free breads often have poor crust and crumb characteristics and the current study was conducted to help alleviate this problem. A commercial wheat starch (Codex Alimentarius) gluten free flour was supplemented with seven dairy powders (0%, 3%, 6%, 9% inclusion rates based on flour weight). Initially a fixed water level was used (trial 1) and the resulting batters were proofed and baked. The breads were tested 24 h after baking. Powder addition reduced loaf volume by circa 6% (P<0.001). Increasing the inclusion levels of the powders decreased loaf volume (P<0.001) with a decrease of 8% for the highest level. Powder addition generally decreased the crumb L^*/b^* (white/yellow) ratio. Crust L^* values were significantly reduced. All of the powders increased crumb hardness (P<0.001) with the exception of demineralised whey powder. Ten and 20% additional water (trial 2) was added to the formulation and the resulting breads had higher volume, and a much softer crust and crumb texture. Sensory analysis revealed a preference for breads containing skim milk replacer, sodium caseinate and milk protein isolate.     

Inulin and oligofructose as fat and sugar substitutes in quick breads (scones): a mixture design approach

Mixture (D-optimal) design was used to investigate the effects of prebiotics such as inulin and oligofructose as fat and sugar replacers on quality parameters of quick breads (scones). Crust and crumb colour increased with the inclusion of prebiotics. Higher concentration of inulin and oligofructose in quick breads also showed a slight increase in crust and crumb hardness. Loaf volume significantly increased with the inclusion of prebiotics. The optimization tool indicated that by using a mixture of margarine (3.53%), oligofructose Orafti^? L95 (10%), caster sugar (0.55%) and inulin Orafti^? GR (5.92%), a quick bread with similar baking properties and textural attributes to the control can be achieved. The mixture design was successfully used to reduce the original levels of 10% fat and 10% sugar (percentages are based on flour weight). The calculated model performance indices accuracy factor and bias factor of the predicted quick-bread formulations showed a high applicability of the model. The variations between the predicted and experimental values obtained were within the acceptable error range, as depicted by the average mean deviation. Therefore, the predictive performance of the established model may be considered acceptable.     

Influence of inulin on physical characteristics and staling rate of gluten-free bread

Inulin preparations with different degree of polymerization (HSI with a DP < 10, GR − DP ? 10 and HPX − DP > 23) were used for the production of gluten-free bread. It was found that an addition of investigated compounds resulted in an increase of loaf volume and reduction of crumb hardness. However, internal structure of the obtained loaves was less uniform and more open than in control bread. Generally, inulin preparations with lower degree of polymerization had stronger effect on all analyzed parameters than that with higher DP. A decrease in staling was observed (measured as the rate of crumb hardening), which was caused by the presence of inulin. The highest content of retrograded amylopectin was found for crumb with HSI, and the lowest for samples with HPX.     

Modification of gluten-free sorghum batter and bread using maize, potato, cassava or rice starch

Gluten-free sorghum bread was made from cassava, maize, potato or rice starch and sorghum in the ratios 10:90, 20:80, 30:70, 40:60 and 50:50. The other baking ingredients, on flour-weight-basis, were water (100%), sugar (6.7%), egg white powder (6%), fat (2%), salt (1.7%) and yeast (1.5%). Increasing starch content changed the batters’ consistencies from soft doughs to thin pourable batters. Increasing starch content decreased crumb firmness and chewiness, and increased cohesiveness, springiness and resilience of all breads. Cassava-sorghum and rice-sorghum breads had better crumb properties than maize-sorghum or potato-sorghum breads. Although the crumb properties of all breads declined (i.e. firmness and chewiness increased; cohesiveness, resilience and springiness decreased) on storage, the formulation containing 50% cassava starch retained the best overall texture.     

Chia (Salvia hispanica L.) as fat replacer in sweet pan breads

The effects of gel from ground chia (Salvia hispanica L.) were studied as a fat replacer in sweet pan breads. This substitution was addressed to reduce the total amount of fat in the product and to improve the nutritional value of the products regarding the fatty acid composition. The effects on the baking results were determined by assessing common baking evaluations and texture analysis after 2 and 48 h. The doughs were characterised with rheometer and rheofermentometer measurements. Rheometer measurements revealed that the replacement resulted in softer doughs with decreasing values for storage and loss moduli with increasing chia content. The yeast activity was increased with incorporated chia gel compared to the control. The best results for the baking experiments were obtained with 25% fat replacement through ground chia gel. Here, the highest volume yield with the softest crumb even after 48 h was achieved.     

Effect of Pear,Apple and Date Fibres from Cooked Fruit By-products on Dough Performance and Bread Quality

This study examined the effect of the incorporation of flesh fibre concentrate (FFC) from apple, pear, and date pomaces on wheat bread dough performance and bread quality. The nutritional composition and techno-functional properties (water-holding capacity, oil-holding capacity, swelling capacity) of FFC were determined beforehand. Dough performance was evaluated by farinograph, alveograph and visco-amylograph. Bread quality was assessed by physical (weight, specific volume, and color) and textural (hardness and elasticity) parameters. Digital imaging analysis was also performed in order to better understand the observed effects. Results showed that the addition of FFC in wheat flour significantly improved (P?<?0.05) dough properties inducing an increase of water absorption (from 55 to 60 %), of stability (from 4 to 31 min),of tenacity (from 83 to 116 mmH₂O) , a reduction of extensibility (from 69 to 29 mm), of softening (from 60 to 20 BU), of breakdown (from 34 to 25 BU) and of setback (from 103 to 93 BU) in comparison to the control dough (without fibre). The formulation containing FFC produced loaves that had various colors (crust, 0?<?ΔE*?<?10 and crumb, 0?<?ΔE*?<?20; ΔE* corresponding to color variation), a comparable specific volume (2.7 vs 2.9 cm³/g for control) and a more aerated internal crumb structure compared to the control. During storage of breads at 20 °C, there was no significant difference (P?<?0.05) between enriched and control bread crumb and crust texture profiles.     

Effect of Fat Replacement by Inulin on Textural and Structural Properties of Short Dough Biscuits

The aim of this study was to evaluate the effects of inulin as fat replacer on short dough biscuits and their corresponding doughs. A control formulation, with no replacement, and four formulations in which 10, 20, 30, and 40 % of shortening was replaced by inulin were studied. In the dough, shortening was observed surrounding flour components. At higher fat replacement levels, flour was more available for hydration leading to significant (P?<?0.05) harder doughs: from 2.76 (0.12)?N in 10 % fat-replaced biscuits to 5.81 (1.56)?N in 30 % fat-replaced ones. Biscuit structure was more continuous than dough structure. A continuous fat layer coated the matrix surface, where starch granules were embedded. In general, weight loss during baking and water activity decreased significantly (P?<?0.05) as fat replacement increased. Biscuit dimensions and aeration decreased when fat replacement increased, e.g., width gain was +1.20 mm in 10 % fat-replaced biscuits and only +0.32 mm in 40 % fat-replaced ones. Panelist found biscuits with 20 % of fat replacement slightly harder than control biscuits. It can be concluded that shortening may be partially replaced, up to 20 %, with inulin. These low fat biscuits are similar than the control biscuits, and they can have additional health benefits derived from inulin presence.     

Quality and antioxidant properties of bread containing turmeric (Curcuma longa L.) cultivated in South Korea

Turmeric (Curcuma longa L.) powder was used to substitute 0%, 2%, 4%, 6% and 8% of wheat flour for making turmeric wheat breads. Proximate composition, physical quality, functional components (curcumin and total phenols) and antioxidant properties of breads containing turmeric were analysed and compared with those of wheat bread. Hardness, crumb colour a and b values, curcumin content and total phenolic contents of breads significantly increased with the addition of turmeric powder. Water activity, specific volume and crumb colour L value of breads decreased with the addition of turmeric powder. Breads containing turmeric powder also showed good antioxidant activity as tested by the β-carotene-linoleate bleaching assay. A 4% substitution of wheat flour with turmeric powder showed acceptable sensory scores which were comparable to wheat bread. Breads containing turmeric powder can thus be developed as a health-promoting functional food.     

The utilisation of barley middlings to add value and health benefits to white breads

The beneficial health effects of β-glucan, a major non-starch polysaccharide in barley, have become the focus of much attention in recent years, with the incorporation of barley fractions into baked products being a growing area in the development of healthier food products. In this study, flour formulations, doughs and breads were produced using the “middling” fraction (M) of wholegrain (WM) and pearled (PM) barley in different ratios (15%, 30%, 45% and 60% middlings with wheat flour). A 100% wheat formulation was used as a control. The protein content differed significantly (P < 0.01) between formulations (i.e. the amount of barley middlings substituted for flour) but did not differ significantly between WM and PM formulations of the same inclusion level. Starch pasting properties were significantly affected by the increased inclusion of barley middlings (BM) into the formulation. Fundamental dough rheology of the samples also showed significant differences between doughs made from different BM levels, with doughs containing BM having increased firmness, decreased resistance to extension and decreased elasticity. Bread quality was not significantly affected by the addition of up to 30% BM, the loaf volume and textural properties in particular of breads up to 30% BM inclusion were of a suitable standard when compared to the control. Both fibre and β-glucan content of the breads was increased significantly with the inclusion of BM; inclusion of BM at a 30% level increased the fibre and β-glucan contents, respectively.     

USE OF ANIMAL BLOOD AND CHEESE WHEY IN BREAD: NUTRITIVE VALUE AND ACCEPTANCE

Breads in which water and milk powder were replaced with unrefined pork blood and/or cottage cheese whey were compared with commercial white bread and an "organic" whole wheat bread. Loaves were evaluated for appearance, composition and acceptance. Rat feeding studies in which the breads contributed about 10% protein to otherwise complete diets indicated no significant differences in growth performance (adjusted PER's) between commercial and "organic" bread. Significantly better performance was obtained for loaves containing blood, whey and blood: whey mixtures. The experimental loaves were comparable in acceptability to commercial breads, although loaf volumes were much lower and crumb texture coarser.     

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.     

Influence of the soluble fibres inulin and oat β-glucan on quality of dough and bread

Bread represents a suitable food product for the addition of functional ingredients, such as the cholesterol-lowering dietary fibre oat β-glucan and the prebiotic inulin. Therefore, these soluble fibres were incorporated into wheat as well as gluten-free bread, and their effects on rheological properties of the dough, on bread quality and on crumb microstructure were compared. The level of remaining β-glucan as well as its molecular weight was determined using an enzyme kit and size-exclusion chromatography. The addition of oat β-glucan resulted in a higher water addition level, whereas incorporation of inulin had the opposite effect. Rheological testing showed that the incorporation of oat β-glucan results in a more elastic dough. The baking characteristics mainly affected by fibre addition were volume and crust colour, with inulin increasing and oat β-glucan decreasing loaf-specific volume in the gluten-free breads. Inulin led to a darkening of the crust of both bread types, whereas addition of oat β-glucan resulted in a lighter crust of gluten-free bread. Oat β-glucan softened the crumb of gluten-free bread, but had the opposite effect on wheat bread. Inulin resulted in an increased crumb hardness as well as the rate of staling. Beta-glucan breakdown was more pronounced in wheat bread than in gluten-free bread. The results show that the use of β-glucan to increase the nutritional value of wheat bread is limited due to negative influences on technological properties. However, this soluble fibre is highly suitable for incorporation into gluten-free bread.     

Combined effects of inulin,pectin and guar gum on the quality and stability of partially baked frozen bread

Many attempts have been made to increase the nutritional value of bread by adding dietary fibre. However, fibre enrichment is usually associated with various technological problems. The aim of this study was to optimise the composition of a blend of inulin, pectin and guar gum to enrich the fibre content of partially baked frozen bread without impairing its technological quality. We prepared 20 formulations following a central composite design, together with 4 control breads. Bread enriched with inulin had higher crumb hardness, lower specific volume, shape, moisture content, and crumb cohesiveness than control bread, but improved flavour. Pectin and guar improved moisture content and crumb cohesiveness. There was no interaction between inulin and pectin for any of the bread attributes investigated, while interactions between inulin and guar were small. In contrast, guar and pectin significantly interacted to decrease volume and increase crumb hardness and chewiness. A desirability function method identified the optimised blend as containing 3% inulin, 0.9–1% pectin and 0.3–0.4% guar. Bread enriched with such blend had the following characteristics: specific volume, 4.06 cm³/g; shape, 0.63; crumb hardness, 189 g; resilience, 0.36; cohesiveness, 0.84; chewiness, 169 g; and flavour score, 4.6. Experimental values were close to the predicted ones, with prediction errors below 10% for all attributes tested. The specific volume, crumb hardness and chewiness of the enriched bread were superior to those of unenriched bread. However, undesirable textural changes occurred in the enriched bread during 12 weeks of frozen storage, and these changes strongly depended on the fibre blend composition.     

Effect of high pressure processing on wheat dough and bread characteristics

Microbial, physical and structural changes in high pressured wheat dough were studied as a function of pressure level (50-250 MPa) and holding time (1-4 min). Thereafter, selected conditions of high hydrostatic processing (HPP) were applied to bread dough and the technological quality of the obtained breads was studied. The effect of HPP on wheat dough was investigated by determining microbial population (total aerobic mesophilic bacteria, moulds and yeasts), color and mechanical and texture surface related dough parameters (cohesiveness, adhesiveness, hardness and stickiness). HPP reduced the endogenous microbial population of wheat dough from 10⁴ colony forming units/g (CFU) to levels of 10² CFU. HPP treatment significantly (P < 0.05) increased dough hardness and adhesiveness, whereas treatment time reduced its stickiness. Scanning electron micrographs suggested that proteins were affected when subjected to pressure levels higher than 50 MPa, but starch modification required higher pressure levels. HPP treated yeasted doughs led to wheat breads with different appearance and technological characteristics; crumb acquired brownish color and heterogeneous cell gas distribution with increased hardness due to new crumb structure. This study suggests that high hydrostatic processing in the range 50-200 MPa could be an alternative technique for obtaining novel textured cereal based products.     

Effect of inulin on rheological properties of soft and strong wheat dough

The influence of inulin with different degrees of polymerisation (DP) on the farinograph characteristics, extensograph parameters and fermentation rheological properties of soft and strong wheat dough was explored. The results showed that the addition of inulin can reduce the water absorption of doughs, and inulin with lower DP had more significant effect and the influence on the soft dough was stronger than the strong dough. Inulin can enhance mechanical properties of the gluten network and improve the resistance to mixing of soft dough. The extensibility of doughs decreased with increasing inulin. Inulin increased the resistance to extension of soft dough; however, it is reverse for strong dough. Adding inulin significantly increased the volume of gas production and the maximum expansion height of doughs, and the effect of inulin with lower DP was more prominent. Additionally, the gas‐holding capacity of doughs was enhanced by inulin.     

Oil bulking agents based on polysaccharide gels in meat batters: A Raman spectroscopic study

A Raman spectroscopic study was performed to determine protein and lipid structural properties in meat batter containing oil bulking agents as pork backfat replacers. Meat batters were prepared with pork backfat (MB-PF) or with a combination of olive oil, sodium alginate, CaSO₄, sodium pyrophosphate and dextrin (MB-A/D) or inulin (MB-A/I) as a fat replacer. Proximate composition, pH, cooking loss (CL), colour and texture were evaluated. MB-A/D and MB-A/I both showed lower (P < 0.05) CL and a^∗ values, higher (P < 0.05) L^∗ and b^∗ values, and higher (P < 0.05) hardness and chewiness. MB-A/I showed the highest hardness and chewiness. Enhancement of the β-sheet structure was observed in MB-A/D and MB-A/I, more so in MB-A/I. There was increased disorder in the oil acyl chains, which involve lipid–protein interactions, in both MB-A/D and MB-A/I. Structural characteristics in proteins and lipids may be associated with specific water and fat binding properties and textural characteristics of meat batters.     

Production of squid emulsion sausages using pork skin and coconut powder mixture as fat replacers

How to improve the inferior properties of squid products is a big challenge for producers. Pork skin and coconut powder (PSCP) mixture were assessed as fat replacers in squid emulsion sausages. The modified treatment containing 100% PSCP had 62.58% less fat, 4.82% more protein and 8.79% more moisture than those of the control (P < 0.05). High PSCP concentration resulted in lower cooking loss, higher emulsion stability and better textural properties. Texture profile analysis (TPA) showed that the addition of PSCP significantly (P < 0.05) increased the hardness, cohesiveness and chewiness of the sausages. The three‐dimensional network structures of the sausages containing PSCP were more compact and homogeneous. Sensory evaluation results produced by a sensory panel comprised of 100 panellists indicated that the sausages had an excellent flavour and overall acceptability when the substitution was 60%. Therefore, pork skin and coconut powder can be used to replace the pork back fat in the squid emulsion sausage without sacrificing the quality.     

Konjac gel for use as potential fat analogue for healthier meat product development: Effect of chilled and frozen storage

The paper reports a study of the physicochemical, rheological and microstructural properties of konjac gels (rehydratated without heat as a cold-set gel) for use as fat replacers in the formulation of reduced/low fat meat products as affected by chilled storage and freezing/thawing. The konjac gel (KG) showed high stability under chilling storage conditions. Water binding capacity (WBC) of KG ranged between 87 and 90%, with no changes (P > 0.05) during chilling storage. Texture profile analysis (TPA) parameters were not affected (P > 0.05) by chilling storage. The rheological behaviour and microstructure confirm the excellent chilling storage-stability of KGs. Freezing/thawing process strongly affected the KG characteristics, with a substantial decrease (P < 0.05) of WBC and increased (P < 0.05) hardness and chewiness, with major morphological changes; however, there were no appreciable changes attributable to frozen storage. The effects of freezing/thawing on fat analogue texture seems to be largely overcome by heating.     

The impact of resistant starch on characteristics of gluten-free dough and bread

The study focused on partial replacement in gluten-free breads of corn starch with tapioca and corn resistant starch preparations. The use of resistant starch resulted in the increase of storage and loss moduli of the dough, and the lowering of loss tangent, which indicates its more elastic character. The incorporation of resistant starch reduced creep and recovery compliance and elevated zero shear viscosity. Modified doughs displayed higher starch gelatinization temperatures and lower viscosities that were proportional to the share of RS. It was found that the loaves baked with the share of resistant starch had less hard crumb than bread without RS addition. The crumb hardness diminished with the increasing amount of applied RS preparation. The addition of resistant starch raised total dietary fibre, by up to 89%, as compared to control (bread without RS addition). The most pronounced change was observed for insoluble dietary fibre (increase 137%), while only slight increase was found for its soluble fraction (18%).