Effects of wheat and rye bread structure on mastication process and bolus properties

Chemical composition, baking process and structure of breads influence their degradation in digestion leading to different postprandial responses. Rye bread has a very different structure as compared to wheat bread, and rye breads are known to induce lower postprandial insulin responses than wheat bread. The aim of this study was to find out potential differences in mastication and initial starch hydrolysis rate of rye and wheat breads. Three rye breads (wholemeal rye, endosperm rye and endosperm rye with gluten) and wheat bread were masticated by fifteen participants and the process was monitored using electromyography. The particle size distribution and initial in vitro starch hydrolysis of the bread boluses were analysed. Specific volume correlated negatively and closed porosity of breads correlated positively with work required for mastication. When compared to wheat bread, wholemeal rye bread required more work for mastication process (p = 0.004). Rye breads were degraded to smaller particles than wheat bread during mastication. There was a trend (p = 0.098) towards slower in vitro starch hydrolysis rate in rye bread boluses than in wheat bread boluses. The results indicate that the digestion process of rye breads differs from that of wheat bread already in the early phase of digestion. This may be one reason behind the unique postprandial responses reported for rye breads.     

Dry-fractionation of wheat bran increases the bioaccessibility of phenolic acids in breads made from processed bran fractions

This study evaluated the potential of using ultra-fine grinding and electrostatic separation of wheat bran as methods to improve the bioaccessibility of para-coumaric acid (pCA), sinapic acid (SA) and ferulic acid (FA) from bran-rich breads. Bran fractions were produced and used to bake white bread, whole-grain bread, and seven different bran-rich breads. The influence of bran particle size and bread composition on the bioaccessibility of pCA, SA and FA was studied using a dynamic computer-controlled in vitro gastro-intestinal model. The amount of bioaccessible phenolic acids was higher in whole-grain bread and bran-rich breads than in white bread, and the finer the bran particles in bran-rich breads, the more bioaccessible the phenolic acids. The highest amounts of bioaccessible phenolic acids were observed for two of the fractions obtained by electrostatic separation of ground bran. Only the free and conjugated phenolic acids forms were found to be bioaccessible, and the bioaccessibility of SA was much higher than that of FA, due to the higher solubility of SA. This study demonstrated that the use of bran fractionation to reduce the particle size, or to include only some parts of the bran in foods, can help developing grain-based products with increased nutritional potential.     

Changes in dietary fiber fractions and gut microbial fermentation properties of wheat bran after extrusion and bread making

The dietary fiber in wheat bran, principally non-starch polysaccharides (NSP), is mostly water-unextractable and is poorly utilized by human gut microbiota. The purpose of this study was to determine the change in water-extractability of NSP in wheat bran upon extrusion and then to determine if extrusion impacts the availability of NSP for fermentation by the fecal microbiota during in vitro fecal fermentation. A secondary objective was to incorporate extruded bran into a product formulation to determine if changes in WE-NSP and NSP fermentation were maintained in a finished product. Bran was extruded using combinations of high or low moisture (15% and 30% wb) and high or low screw speed (120 and 250 rpm). All extrusion conditions resulted in increases in WE-NSP and fecal microbiota short chain fatty acid (SCFA) production upon fermentation compared with unextruded bran. Low screw speed and low moisture resulted in the greatest increase in WE-NSP (3-fold) as well as the highest production of SCFA during fermentation (1.4-fold) compared with unextruded bran. Whole wheat breads containing extruded bran did not show increases in either WE-NSP or SCFA production compared with the control. In conclusion, extrusion of wheat bran increased WE-NSP, which enabled greater fermentability by human fecal microbiota. However, once extruded bran was used in a whole wheat bread formulation the changes in fermentation outcomes were no longer evident.     

Effect of extruded wheat bran on dough rheology and bread quality

Bran extrusion is mainly under study and works should be performed to know the effect on dough and bread. This study was designed to investigate the effect of bran extrusion (addition of 2.5 g/100 g to 20 g/100g bran) on the rheological characteristics of bread dough, behaviour during fermentation, and bread quality. Extruded bran increased dough development time and tenacity to a greater extent than non-extruded bran, and minimized the loss of stability if over-mixing occurred. Extruded bran, due to its greater gas production, also reduced loss of dough height during fermentation to a greater extent than untreated bran. However, breads with extruded bran showed a higher volume and lower initial firmness than breads with normal bran if improver was added. However, no differences were found in the organoleptic evaluation. Bran extrusion therefore modified dough rheology but did not negatively affect bread quality. It could even improve the quality of breads with bran when improvers are added.     

Influence of Cephalaria Syriaca Addition on Physical and Sensorial Properties of Wheat Bran Bread

The effect of different Cephalaria syriaca products (CSP) (whole Cephalaria syriaca flour (WCSF) and defatted Cephalaria syriaca flour (DCSF)) on the final quality of bran breads was investigated. Five levels of Cephalaria syriaca products (0.16, 0.50, 0.84, 1.17, and 1.51 g/100 g bread) were used in this study. Results of this study showed that addition of CSP (WCSF and DCSF) to wheat bran bread had significant positive impact on bread specific volumes, crumb firmness and bread sensory characteristics, although addition levels (0.16, 0.50, 0.84, 1.17, and 1.51 g/100 g bread) were very low. In general, specific volume, yield of volume, and some sensory characteristics of the bran bread increased when the addition levels of WCSF and DCSF increased, except for the level of 1.51 g/100 g bread CSP addition, in which a slight decrease was observed. Bran breads containing WCSF had significantly higher loaf specific volume, softness of breadcrumb and sensory characteristics than those of breads containing DCSF at all addition levels. Especially, the addition of 1.17 g WCSF significantly improved the quality of bran breads. This study indicates that these two CSP can be used as additives in bran bread production in order to improve the quality of bread.     

The effect of pea (Pisum sativum L.)‐originated asparaginase on acrylamide formation in certain bread types

The aim of this study was to investigate the effect of pea (Pisum sativum L.)‐originated asparaginase on acrylamide formation in white wheat, wheat bran and whole‐grain wheat breads. Two‐day germinated pea flour was used at 0%, 1%, 3% and 5% levels for each bread type. Acrylamide analysis was performed with liquid chromatography–mass spectrometry. Besides, colour and sensory properties of the breads were evaluated to search out the effects of pea flour substitution on the consumer acceptance. Reduction of acrylamide in white wheat bread was not found significant and addition of pea flour decreased the acceptance. However, it was found that acrylamide level can be reduced by 57% and 68% with addition of 5% pea flour in wheat bran and whole‐grain breads, respectively, without any negative impact on colour and sensory properties.     

Xylanase-mediated in situ production of arabinoxylan oligosaccharides with prebiotic potential in whole meal breads and breads enriched with arabinoxylan rich materials

Multiple studies have revealed the prebiotic activity of cereal derived arabinoxylan oligosaccharides (AXOS). This study investigated the in situ production of AXOS during bread making. In the first part, the AXOS producing capacity of different xylanases was compared in whole meal bread making. Three mesophilic xylanases originating from Bacillus subtilis, Aspergillus niger and Hypocrea jecorina, and one thermophilic xylanase from H. jecorina (HjXynA), were used in different dosages. At dosages that did not impair dough manageability, HjXynA solubilised and cleaved the arabinoxylan fraction to the largest extent, resulting in an AXOS content of 2.1% (dry basis) and an average degree of polymerisation (avDP) of 9. In the second part, the impact of HjXynA on the AXOS levels in dietary fibre enriched breads was studied. Rye or wheat bran fortified breads treated with HjXynA yielded good quality breads with AXOS levels above 2.0% with an avDP of 26 and 19, respectively.     

Comparison of glycemic index of spelt and wheat bread in human volunteers

The assessment of the glycemic index (GI) seems to be an important parameter to take into account in order to better understand the physiologic effects of foods with high carbohydrate levels. Among cereals, which are major sources of carbohydrates, spelt (Triticum spelta L.) has been considered as particularly interesting from a nutritional point of view. The aim of this study was to evaluate in vivo the GI of white spelt bread in healthy subjects. The wheat (Triticum aestivum L.) white bread was used as reference food. To avoid differences in the production of both breads, spelt and wheat breads were baked under the same controlled conditions. Results showed that the glycemic profile of spelt white bread was not different from that of wheat white bread (GI of 93 ± 9). The area under the glycemic curve significantly and negatively correlated to fasting glycemia and carbohydrate intake during evening meals preceding the test. In conclusion, the glycemic response to spelt bread was similar to that of wheat bread. However, in order to avoid more inter-individual variability, our data supports the importance to propose standardised carbohydrate content for the last meal before evaluating the GI of food.     

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.     

Quality and antioxidant property of buckwheat enhanced wheat bread

Common buckwheat (Fagopyrium esculentum Moench) was used to substitute 15% of wheat flour to make buckwheat enhanced wheat breads. Proximate composition, physical quality, functional components and antioxidant properties of buckwheat enhanced wheat breads were analysed and compared with those of white bread. Specific volumes of three breads were 6.10–6.75 cm³/g. Buckwheat enhanced wheat bread showed lower lightness and whiteness index values and higher redness and yellowness values. On a seven-point hedonic scale, all sensory results were 5.33–5.91, indicating that three breads were moderately acceptable. No differences were found in appearance, colour and overall sensory attributes for three breads, whereas both buckwheat enhanced wheat breads were rated higher in flavour and mouth feel. Buckwheat enhanced wheat bread contained more rutin and quercetin as expected. Buckwheat enhanced wheat bread was good in antioxidant activity, reducing power and 1,1-diphenyl-2-picrylhydrazyl radical scavenging ability with unhusked buckwheat enhanced wheat bread being the most effective. Overall, buckwheat enhanced wheat bread could be developed as a food with more effective antioxidant properties.     

Wheat bran particle size effects on bread baking performance and quality

Commercial hard red spring, hard red winter, soft white and durum wheat brans were used to evaluate the particle size effect of wheat bran on bread baking performance and bread sensory quality. Three different particle size bran samples were obtained from each bran by grinding, not by sifting, the bran samples. The bran samples were similar in chemical composition, but different in particle sizes. Results of baking experiments showed that breads containing fine bran had lower specific loaf volume and darker crumb colour than breads containing coarse or medium size bran. Sensory test panellists found that fine bran contributed smoother crust appearance and less gritty mouthfeel than the coarse bran. The sensory panel also indicated that breads containing soft white wheat bran had significantly better flavour and mouthfeel than breads containing hard red spring wheat bran. © 1999 Society of Chemical Industry     

Optimisation of sourdough bread incorporation into wheat bread by response surface methodology: Bioactive and nutritional properties

The optimisation of the quantity of sourdough (A) prepared with two different fermentation methods, [spontaneous fermentation (F1) vs. starter of lactic acid bacteria‐added fermentation (F2)], instant active dry yeast (B) and wheat bran (C) for a nutritionally improved bread formulation has been studied by evaluating the bioavailability and bioactive properties. The bread produced according to the optimised formula and fermentation types of F1 (OB_F1) and F2 (OB_F2) was compared with control bread (CB). The optimised levels for F1 were 11.45% for sourdough, 1.10% for dry yeast and 1.58% for wheat bran and for F2 6.99% for sourdough, 1.02% for dry yeast and 38.84% for wheat bran. The addition of sourdough significantly (P < 0.05) affected antioxidant activity, total phenolic content, in vitro ash and protein digestibility, and enzyme resistance starch contents of bread. The F1 fermentation method was found to be more effective in terms of bread properties examined.     

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.     

发酵麸皮混合物对面包品质的影响

为改善麸皮面包的品质,增加麸皮的利用率,本实验应用甜酒曲联合酵母发酵麸皮、黄豆和花生的混合物,得到发酵麸皮混合物。以面粉+发酵麸皮混合物总量为100 g(面粉90 g、发酵麸皮混合物10 g)计,制备发酵麸皮混合物面包(简称发酵麸皮面包),以普通面包、麸皮面包及添加黄豆、花生混合物的非麸皮添加物面包为对照,对这几种面包的品质、风味物质及抗氧化活性进行分析。结果表明:黄豆、花生的添加能够起到提升面包风味的作用;发酵麸皮混合物的添加可以改善麸皮面包的品质,其感官评分、弹性、硬度和色差L、b值极显著优于麸皮面包(P0.01),而与普通面包比较没有显著差异(P0.05);与3种对照面包样品比较,发酵麸皮面包的醇类、酯类和醛类等风味成分种类较多,且分布均匀,而且还检测出其特有的风味物质,分别为吡嗪类、呋喃类、乙基酯类;发酵麸皮面包的多酚、黄酮含量以及抗氧化活性指标也均最高。综上,发酵麸皮混合物能够改善麸皮面包的品质,并提高面包的抗氧化活性。     

Application of Kluyveromyces marxianus, Lactobacillus delbrueckii ssp. bulgaricus and L. helveticus for sourdough bread making

The application of Kluyveromyces marxianus (IFO 288), Lactobacillus delbrueckii ssp. bulgaricus (ATCC 11842) and Lactobacillus helveticus (ATCC 15009) as starter cultures for sourdough bread making was examined. Production of lactic and acetic acids, bread rising, volatile composition, shelf-life and organoleptic quality of the sourdough breads were evaluated. The amount of starter culture added to the flour, the dough fermentation temperature and the amount of sourdough used were examined in order to optimise the bread making process. The use of mixed cultures led to higher total titratable acidities and lactic acid concentrations compared to traditionally made breads. Highest acidity (3.41 g lactic acid/kg of bread) and highest resistance to mould spoilage were observed when bread was made using 50% sourdough containing 1% K. marxianus and 4% L. delbrueckii ssp. bulgaricus. The use of these cultures also improved the aroma of sourdough breads, as shown by sensory evaluations and as revealed by GC–MS analysis.     

Processing of rye bran influences both the fermentation of dietary fibre and the bioconversion of lignans by human faecal flora in vitro

Plant lignans are converted to mammalian forms, enterodiol and enterolactone, in the colon. Enhanced plasma or urinary enterolactone levels have been associated with lowered risk of cardiovascular diseases and breast cancer. Processed rye bran and its fractions were compared to ascertain the fermentation rates of fermentable carbohydrates and the bioconversion of lignans. Rye bran was extruded and treated with a food‐grade xylanase. Part of the xylanase‐treated rye bran was separated into a soluble rye bran extract and an insoluble residue, and a part of the xylanase‐treated rye bran was freeze‐dried without separation. All the samples were digested by pepsin and pancreatin and subsequently fermented with a human faecal inoculum in vitro. The consumption of carbohydrates, the productions of short‐chain fatty acids (SCFA), enterodiol and enterolactone were followed as a function of time. The soluble rye bran extract showed the fastest fermentation rate and the highest extent of fermentation determined as the consumption of neutral sugar residues (arabinose, xylose and glucose), the production of SCFA and the formation of enterodiol and enterolactone. Xylanase treatment enhanced the fermentation rate of extruded rye bran. An even a higher fermentation rate was observed for rye bran extract containing soluble carbohydrates. The amount of enterolactone precursors in rye seemed to be too low for enterolactone formation using an amount of substrate suitable for carbohydrate fermentation. However, xylanase treatment enhanced the availability of plant lignans from rye bran, as enterodiol formation was increased by the use of xylanase. Copyright © 2005 Society of Chemical Industry     

Effect of adding wheat bran and germ fractions on the chemical composition of high-fiber toast bread

The effect of the type of bran, level of addition, particle size and addition of wheat germ on the chemical composition of high-fiber toast bread was investigated. The bran and germ fractions were found to be high in ash, protein, fat and total dietary fiber contents. The wheat germ had a protein content of 27.88% compared with 11.35, 12.69 and 15.76% for white flour, whole wheat flour and red fine bran, respectively. The chemical composition of high-fiber breads, in terms of minerals, protein, fat and dietary fiber contents, was found to be far superior than that of the whole wheat flour (control) bread sample. Considering these results, it can be concluded that high-fiber toast bread, with lighter crumb color and improved sensory and nutritional qualities than the whole wheat flour bread, can be produced using white flour, and equal proportions of coarse and fine bran at 20%, germ at 7.5%, and sodium stearoyl-2-lactylate at 0.5% levels.     

Increasing the health benefits of bread: Assessment of the physical and sensory qualities of bread formulated using a renin inhibitory Palmaria palmata protein hydrolysate

This study examined the textural and sensory effects of bread formulated using a Palmaria palmata protein hydrolysate with in vitro renin inhibitory properties. Four formulations were examined; a wheat flour control bread, a control bread containing 4% P. palmata protein hydrolysate, a buckwheat bread consisting of a blend of 70% wheat: 30% buckwheat, and a fourth formulation of the buckwheat bread containing 4% P. palmata hydrolysate. The volume, colour, texture profile, moisture, crumb structure, sensory attributes and renin inhibitory activity of all four baked breads are presented. Bright field light microscopy and confocal scanning laser microscopy images using a new triple labelling protocol were also obtained to visualise the main ingredients of the breads. It was observed that the addition of 4% P. palmata protein hydrolysate to the wheat bread control did not affect the texture or sensory properties of the bread to a large degree. Furthermore, when compared to the control, the bread containing the hydrolysate retained renin inhibitory bioactivity after the baking process. This study highlights that baked products may be a suitable delivery vehicle for bioactive compounds. The study demonstrates that the health value of bread was increased through the addition of a seaweed protein hydrolysate.     

Bioaccessibility,changes in the antioxidant potential and colonic fermentation of date pits and apple bagasse flours obtained from co-products during simulated in vitro gastrointestinal digestion

The aims of this work were to evaluate the effect of in vitro gastrointestinal digestion (GID) on (i) the recovery and bioaccessibility indexes, (ii) the changes on antioxidant activity and (iii) the short chain fatty acid (SCFA) production of two DF rich extracts (date pits flour (DPF) and apple bagasse flour (ABF)) obtained from agro-industrial co-products. At the end of GID process, the bioaccessibility of phenolic compounds present in DPF and ABF was 78.54 and 91.58%, respectively. With regard to antioxidant activity, GID increased the chelating activity and reducing power. However, the scavenging properties were reduced. Fermentation of DPF and ABF by colonic bacteria generated SCFA such as formiate, succinate, acetate, propionate and butyrate. These findings suggest that DPF and ABF might be used as potential food ingredients due to GID produced that bioactive compounds released from the matrix which exerts antioxidant activity.     

Determination of nutritionally important starch fractions of some Turkish breads

By using an in vitro technique that measures the rate and extent of starch digestion, the starch in a food can be classified as rapidly-digestible starch (RDS), slowly-digestible starch (SDS) and resistant starch (RS). The amount of these fractions in rye bread, wheat bran bread and corn flour bread were calculated from the experimentally determined values obtained by controlled enzymatic hydrolysis and measurement of released glucose by colorimetry, using a glucose oxidase kit. Free glucose and total starch analysis were also carried out to calculate rapidly-available glucose (RAG) content and starch digestibility rate index (SDRI) of breads. RDS content of the rye bread was higher than the wheat-bran bread and corn flour bread (P<0.05). SDS contents of all breads were not significantly different from each other. Wheat bran bread was found to have a significant amount of RS (6.6%; on dry matter basis) when compared to the other breads (P<0.05). A significant negative correlation (r=−0.95, P<0.05) was also found between RS content and SDRI value of breads.