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 Germ on Dough Rheology and Bread Quality

Wheat germ, a by-product of the milling industry, has interesting nutritional properties. However, it has limited use due to a high risk of rancidity, which could be reduced by using certain thermal treatments such as extrusion. The aim of this study was to investigate how wheat germ extrusion affects the changes induced by its addition to bread dough. For this purpose, different quantities of extruded or raw wheat germ (2.5, 5, 7.5, 10, and 20?g/100?g flour) were added to bread dough. Rheological characteristics of the dough and final quality characteristics of the bread were analysed from both the physical and the sensory points of view. Wheat germ addition increased water absorption and development time but decreased stability after over-kneading, dough tenacity, extensibility, and dough alveographic strength. The addition of extruded wheat dough improved stability and decreased extensibility and strength. Bread made from dough with added wheat germ presented decreased volume, cohesiveness, and elasticity and increased firmness. However, extrusion increased the volume of breads with added wheat germ and improver and decreased firmness. All breads obtained positive acceptability scores in sensory analysis, although wheat germ addition (10?g/100?g flour) slightly decreased texture, appearance, and overall acceptability scores of breads. Germ extrusion therefore improves dough rheology and bread quality and constitutes a suitable treatment to stabilise wheat germ in bread dough.     

Effect of Lactobacillus brevis-based bioingredient and bran on microbiological,physico-chemical and textural quality of yeast-leavened bread during storage

The effects of wheat bran and of a Lactobacillus brevis-based bioingredient (LbBio), obtained after growth in flour-based medium, on quality of yeast-leavened wheat bread (WWB) were investigated. Bran was used in bread formulation by substituting a part (20 g/100 g) of white wheat flour (WBB), while LbBio was used instead of the water content (WWB + LbBio and WBB + LbBio). The use of LbBio in WWB resulted in the biological acidification of the dough due to lactic, phenyllactic and OH-phenyllactic acid contents determining a high fermentation quotient value and an improved bread texture and microbiological quality. Conversely, wheat bran reduced the specific volume and crumb hardness during storage at 25 °C, and affected the antibacterial ability of LbBio during 30 °C storage. Our findings demonstrated that LbBio counteracted the negative effects of bran and allowed to obtain an enriched fibre bread with specific volume and soft crumb comparable to bread without bran.Industrial relevanceBread is a perishable food with a short microbiological and physico-chemical shelf-life. The main microbiological alteration occurring into few days after baking is the “rope spoilage” caused by spore-forming bacteria originating from raw materials. This phenomenon, often misinterpreted as a sign of unsuccessful dough leavening and not visible from outside, is more common under industrial production conditions during the hot season causing large economic losses in the warm climates of Mediterranean countries, Africa and Australia. The use of sourdough often controls this alteration even if the industrial application of this traditional process is limited by the long leavening times. In this study, an innovative procedure for the preparation of yeast-leavened bread comprising the addition of a fermentation product from Lactobacillus brevis grown in a flour-based medium has been applied. The resulting fermentation product (LbBio bioingredient) acts as a sourdough acidifying the dough and improving the textural, physico-chemical and microbiological properties of the resulting bread. The application of bioingredient LbBio could represent an innovative strategy in industrial bread production to obtain acidified yeast-leavened products, thus, preventing the ropy spoilage and reducing the negative effects of bran addition.     

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.     

Effects of wheat sourdough process on the quality of mixed oat-wheat bread

The aim of this work was to study the effects of sourdough fermentation of wheat flour with Lactobacillus plantarum, on the quality attributes of mixed oat-wheat bread (51 g whole grain oat flour and 49 g/100 g white wheat flour). Emphasis was laid both on β-glucan stability as well as bread structure and sensory quality. The variables of the sourdough process were: dough yield (DY), fermentation time, fermentation temperature, and amount of sourdough added to the bread dough. The sourdough process was shown to be a feasible method for mixed oat-wheat bread, and, when optimized, provided bread quality equal to straight dough baking. A small amount (10g/100 g dough) of slack sourdough fermented at high temperature for a long time resulted in the most optimal sourdough bread with the highest specific volume (3.5 cm³/g), the lowest firmness after 3 days storage (0.31 kg), and low sensory sourness with high intensity of the crumb flavour. Wheat sourdough parameters did not affect the content of oat β-glucan in the bread. Additionally, both straight dough and sourdough bread contained 1.4-1.6 g β-glucan/100 g fresh bread. The average molecular weight of β-glucan was 5.5 × 10⁵ in both types of bread, while that of oat flour was 10 × 10⁵. This indicates that a slight degradation of β-glucan occurred during proofing and baking, and it was not affected by variation in the acidity of the bread between pH 4.9-5.8.     

发酵麦麸对面包膳食纤维组成及烘焙特性的影响

采用马克斯克鲁维酵母发酵麦麸制得富含天然酶的功能配料,分析麦麸发酵过程中纤维素酶活力变化,比较制作的麦麸面包(B₁)、发酵麦麸面包(B₂)、木聚糖酶麦麸面包(B₃)和复合麦麸面包(B₄)的膳食纤维组成及烘焙特性的差异。结果表明:马克斯克鲁维酵母具有较强的胞外β-葡萄糖苷酶生产能力,其酶活为6.98 U/g;在48 h麦麸发酵过程中,外切葡聚糖酶和β-葡萄糖苷酶的酶活不断提高,其酶活分别增加至6.06和21.70 U/g,不溶性膳食纤维(IDF)也持续降解至38.30 g/100 g。面团搅拌、醒发过程中,还原糖含量不断增加,且添加发酵麦麸的面包效果最明显。相比未发酵麦麸面包,添加发酵麦麸的面包体积、弹性及持水力都显著提升(p<0.05),气孔结构更加细腻。制作的4种面包中总膳食纤维(TDF)和阿拉伯木聚糖(AX)含量没有显著差异,而添加发酵麦麸及木聚糖酶都能促进面包中IDF和AX溶解。     

Effect of addition of protein concentrates from natural and yeast fermented rice bran on the rheological and technological properties of wheat bread

The effect of substituting wheat flour with 0%, 5%, 10% and 15% protein concentrates from natural and yeast fermented rice bran on the rheological properties of their dough and bread properties was studied. Rheological properties of wheat dough were influenced by addition of rice bran protein concentrates. Overall acceptability score and specific loaf volume of 100% wheat bread were not significantly different from composite bread up to 10% rice bran protein substitution, and therefore, the optimised level of substitution was established. The optimised composite bread contained higher total amino acid content, radical scavenging activity and ferric reducing ability power (43.04–48.87 g/100 g, 182.77–201.65   mmol TEAC/100 g and 613.29–637.81 mmol TE/100 g) than control (33.86 g/100 g, 109.43 mmol TEAC/100 g and 540.13 mmol TE/100 g). Springiness, cohesiveness and resilience values of wheat bread were not significantly different from composite bread. Scanning electron microscopy revealed that composite bread had surfaces with embedded granules like protein deposits with small spores.     

Interaction effects of fermentation time and added asparagine and glycine on acrylamide content in yeast-leavened bread

The interaction effects of fermentation time and added asparagine and glycine on acrylamide precursors (asparagine and reducing sugars) in dough and content of acrylamide in yeast-leavened wheat bread were studied. Two experiments, with low and high levels of added asparagine (0–0.044 and 0.071–0.476 g/100 g flour, respectively), were performed. Glycine was added (0.042–0.380 g/100 g flour) only in the high asparagine addition experiment. The fermentation time, which was varied between 13 and 164 min, showed a reducing effect on acrylamide precursors in the dough in both experiments (p < 0.001). These effects of fermentation were more pronounced in the experiment with low asparagine levels, which resembled levels in ingredients. In contrast, fermentation time did not affect the content of glycine in the dough. Added asparagine increased the levels of asparagine in dough and of acrylamide in bread (p < 0.001). A strong correlation was found between the contents of asparagine in the fermented dough and acrylamide in breads at all levels of asparagine. Glycine significantly increased the colour intensity and reduced the acrylamide in bread (p < 0.001) with the latter effect being dependent on the level of asparagine.     

Enzymatic Reduction of Phytate in Whole Wheat Breads

The presence of phytate in flour may be responsible for reduced bioavailability of iron, magnesium, zinc, and calcium from bread. The effect of various concentrations of commercial phytase or phosphatase added to whole wheat flour-yeast doughs on their phytate and nonphytate phosphorus content has been investigated. By using 2.0% (flour basis) of phytase and 0.11% phosphatase the initial phytate phosphorus concentration of the dough was reduced to 1/8 and 1/12 of its initial values, respectively. Storage of the whole wheat breads for up to 96 hr at room temperature showed further significant reduction of phytate phosphorus. The phytate phosphorus content of yeast leavened whole wheat breads decreased during 2 hours of dough fermentation, baking and the subsequent 48 hours of storage at room temperature from 24 mg/100g dough (dry matter) to 1.7 mg/100g bread (dry matter); the phytate phosphorus continued to decrease and after 96 hours storage it was 0.6 mg/100g bread.     

Properties of yeast free bread produced by supercritical fluid extrusion (SCFX) and vacuum baking

A novel technology, supercritical fluid extrusion (SCFX), allows for continuous production of yeast-free dough leavened via incorporation of supercritical carbon dioxide (SC-CO₂). In this study, an optimum dough formulation, SCFX leavened dough production and baking procedures were developed. A premixed dough was leavened by 1% (feed basis) SC-CO₂ injection in a twin screw extruder at 37 °C. Specific mechanical energy input was 18 kW h/ton. SCFX leavened dough and bread density, moisture content, bake loss, texture profile analysis (TPA) and stress relaxation were evaluated and compared to conventional yeast leavened breads throughout 5-day storage. A combination of vacuum and conventional baking yielded the lowest SCFX leavened bread density of 0.19 g/cm³ and crumb hardness comparable to conventional yeast leavened and commercial products. This approach could be beneficial for a continuous production of consistent ready-to-bake dough and breads having equivalent quality to commercial products but produced in shorter time and without ethanol emission issues.

Industrial relevance

The dough leavening process in conventional bread production is an industrial hurdle for a number of reasons. First, it is very time consuming. Dough leavening through yeast fermentation can take up to eight hours, which is not conducive to high production rates. This long waiting period also means a great deal of storage space is required to produce a large amount of dough. This storage environment must be carefully controlled in terms of temperature, humidity, and air conditions in order to maintain optimal yeast fermentation, which can also be very costly. Finally, the emission of ethanol, a significant byproduct of yeast fermentation, must be controlled according to the EPA clean air act. Expensive catalytic converters must be installed and maintained in commercial bread production facilities.Bread produced by super critical fluid extrusion (SCFX) overcomes these problems. Total dough production time is less than an hour, and with the proper baking equipment, the entire process can be made continuous. This means constant output, less downtime, and none of the costly storage space used for conventional dough proofing. Furthermore, since there is no yeast being used, there is no ethanol being produced. This means no harmful volatile organic emissions and no expensive catalytic converter. Coupled with vacuum baking, this process results in bread with qualities similar to commercially produced bread in significantly less time.     

挤压米糠发酵生产γ-氨基丁酸的工艺条件优化

米糠经双螺杆挤压机挤压处理后作为原料,以米曲霉为菌种,采用液体和固体两种发酵方法生产γ-氨基丁酸(GABA),研究米糠挤压处理工艺对GABA产量的影响。结果表明：米糠经不同挤压条件处理后进行发酵生产,其产物中γ-氨基丁酸的含量也不同。米糠的最适挤压处理条件为：物料米糠含水率20%、螺杆转速200r/min、挤压温度150℃,使用该条件处理得到的米糠进行发酵生产γ-氨基丁酸,液体发酵产物中γ-氨基丁酸含量为118.6mg/100g,固体发酵产物所得γ-氨基丁酸含量为121.1mg/100g。     

Effect of Soda Leavening on Phytic Acid Content and Physical Characteristics of Middle Eastern Breads

The effect of soda (sodium bicarbonate) as a leavening agent on pH, phytic acid hydrolysis and physical quality of a fermentation model system and two popular Middle Eastern breads, Iranian taftoon and Pakistani naan (Arabic) were studied. Supplementing 0.2 and 0.4% soda invariably decreased phytic acid hydrolysis. In sour starter supplemented dough, phytic acid was reduced by 82% after 3 hr. However, when 0.4% soda and sour starter were added loss of phytic acid did not exceed 29%. Supplementing soda in taftoon and naan bread formula significantly lowered phytic acid hydrolysis during fermentation. Soda had no apparent improvement on physical quality of breads but increased the dough water absorption and lengthened the mixing time.     

Ver?nderung der Malat- und Citratgehalte bei der Herstellung von Sauerteigbroten

Zusammenfassung Die Veränderung von mehleigenem Malat und Citrat im Verlauf des Herstellungsprozesses von Sauerteigbrot bei Zusatz von Konservierungsstoffen, bei Spontansauer- und Vorteigführung sowie bei Verwendung von Roggenbackschroten wurde untersucht.Von den Konservierungsstoffen hemmt Calcium-propionat im Gegensatz zu Sorbinsäure Panosorb den Malat- und Citratabbau.In einem spontan gärenden Roggenteig werden Malat und Citrat wie in einem herkömmlichen Sauerteig abgebaut.Der Malatgehalt eines mit Weizenmehl-Vorteig hergestellten Brotes lag mit 38 mg/100 g i.Tr. ebenso hoch wie bei einem Brot aus langstehendem Grundsauer.Die Malatgehalte der Schrotbrotkrumen betrugen 14–26 mg/100 g i. Tr., die Citratgehalte 18–28 mg/100 g i. Tr. und lagen damit deutlich höher als bei Mehlbroten analoger Herstellung.

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Changes of malate and citrate content in the production of sour dough breads2. Influence of Preservatives, Spontaneous Rye Dough Fermentation, Wheat Predough, Rye Meal Sour Dough

Summary Changes in malate and citrate content in sour dough bread were examined as related to addition of antifungal preservatives, use of spontaneous fermenting rye dough, use of wheat predough and use of coarse ground rye grain.Calcium propionate retards reduction of malate and citrate in dough, whereas Panosorb (sorbic acid for use in bread) does not influence the degradation of these acids.In spontaneously fermenting rye dough without addition of starter sour dough the speed of reduction of malate and citrate content is equal to conventional sour dough, whereas bread made up from this spontaneous sour dough is of poor sensory quality.The amount of malate in bread from wheat predough was 38 mg/100 g dry matter, which is equal to bread from sour dough with long fermentation times.Malate content of sour dough bread from coarse ground rye grain was in the range of 14 and 26 mg/100 g dry matter, citrate content in the range of 18 and 28 mg/100 g dry matter, which is higher than in flour breads with analogous sour dough process.

     

IMPROVEMENT OF THE WHEAT AND CORN BRAN BREAD QUALITY BY USING GLUCOSE OXIDASE AND HEXOSE OXIDASE

The effects of addition of wheat (10, 20 and 30%) and corn bran (10 and 20%) on rheological and bread making properties of flour were examined. To improve dough and bread properties, glucose oxidase (GO) and hexose oxidase (HO) (15–30 and 45 mg/kg) were used separately in each bran-wheat flour formula with L-ascorbic acid at 75 mg/kg, glucose at 0.5% and vital gluten at 9.2%. Water absorption and development time increased as the amount of wheat and corn bran increased, while dough stability, maximum resistance to extension, extensibility, energy and loaf volume decreased. Corn bran was found to be more detrimental to dough rheology and bread characteristics than wheat bran. Corn bran and wheat bran could be used at bread making up to levels of 10 and 20%, respectively. Addition of 30 mg/kg of HO in combination with constant additives was most effective in improving dough and bread characteristics and GO with its 15 mg/kg usage level followed it. Further increasing of enzyme levels led to over oxidizing of doughs and breads.

PRACTICAL APPLICATIONS

Corn bran up to 10% and wheat bran up to 20% levels can be used in bread making. To improve dough and bread quality, besides L-ascorbic acid (75 mg/kg) and vital gluten (as a percentage of added bran weight), GO (15 mg/kg) or HO (30 mg/kg) could be incorporated into wheat flour-bran mixtures. However, the amount of enzyme should be carefully chosen because when they are used above the mentioned levels, they cause overoxidation of doughs and small loaf volumes are obtained. As a conclusion; by using the corn bran, which is a by-product of the starch industry, not only could it be possible to offer healthy alternative breads which contain high amounts of dietary fiber to consumers, but it could also be possible to obtain economical value by evaluating such a by-product in the bread industry.     

Physicochemical properties of bread dough and finished bread with added pectin fiber and phenolic antioxidants

Comparative studies were conducted in this paper to investigate the effects of added dietary fiber (DF) and/or phenolic antioxidants on the properties of bread dough and finished bread. Breads were developed in the absence (control bread), or presence of apple pectin and/or fruit phenolic extracts (treated breads), and subjected to quality evaluation (attributes including color, weight, and volume) and characterization of chemical and rheological properties. Chemical analyses revealed that breads with added phenolic extracts had greater antioxidant activity and higher extractable phenolic content, than control bread and the treated breads with added apple pectin(s). The measured antioxidant activity was mainly derived from the phenolics present in bread. Storage modulus G' (elasticity) and loss modulus G″ (viscocity) of the treated bread dough with added pectin(s) only were higher than those of control dough. The G' or G″ of the treated breads incorporated with a combination of a pectin and fruit phenolic extract depended on the type of phenolic extract (that is, apple and blackcurrant extracts behaved differently from kiwifruit extract). The G' and G″ at the final baking step were higher than those of other stages, indicating an increase in cross-linking among polymeric molecules and bread particles of high molecular weight. We conclude that the added pectin and/or phenolic extract had influenced bread dough cross-linking microstructure and bread properties through being involved in the interactions with bread components such as wheat proteins during dough development and bread baking. PRACTICAL APPLICATION: Dietary fibers and phytochemicals (including phenolic antioxidants) have long been recognized as the active nutrients responsible for the health benefits of fruit and vegetables to humans. Interest in incorporating bioactive ingredients such as dietary fiber and phenolic antioxidants into popular foods like bread has grown rapidly, due to the increased consumer health awareness. The added bioactive ingredients may or may not promote the development of bread dough. This paper reports the findings associated with the properties of the functional breads enhanced with apple pectin and apple, blackcurrant, and kiwifruit phenolic extracts. Results of this paper indicate that the success of the development of such functional breads is ultimately determined by the interactions among added bioactive ingredients and other bread components.     

Evaluation of Leuconostoc citreum HO12 and Weissella koreensis HO20 isolated from kimchi as a starter culture for whole wheat sourdough

Leuconostoc citreum HO12 and Weissella koreensis HO20 isolated from kimchi were evaluated as starter cultures in the making of whole wheat sourdough bread. After 24 h of fermentation at 25 °C, both lactobacilli grew to the final cell numbers of ca. 10⁹ cfu/g dough, and both doughs had similar pHs and total titratable acidities. In addition, the fermentation quotient of the dough with Lc. citreum HO12 was slightly lower than that of the dough with W. koreensis HO20 (1.6 versus 2.8). Sourdoughs and bread with 50% sourdough produced with the starter cultures exhibited consistent ability to retard the growth of bread spoilage fungi (Penicillium roqueforti and Aspergillus niger) and rope-forming bacterium (Bacillus subtilis). Sourdough breads underwent a significant reduction in bread firming during storage. It seems that both lactobacilli have the potential to improve the shelf-life of wheat bread. The results indicate that the selected lactobacilli have unique fermentation characteristics and produce sourdough breads with overall satisfactory quality.     

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

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

Application of Bifidobacteria as Starter Culture in Whole Wheat Sourdough Breadmaking

This investigation is aimed at developing a new cereal-based product, with increased nutritional quality, by using Bifidobacterium pseudocatenulatum ATCC 27919 as starter in whole wheat sourdough fermentation and evaluating its performance. Four different sourdough levels (5%, 10%, 15%, and 20% on flour basis) in bread dough formulation were analysed. The effects of the use of bifidobacteria in sourdough bread were comparatively evaluated with controls (yeast and/or chemically acidified sourdough with antibiotics). The sourdough and dough fermentative parameters analysed were pH, total titratable acidity, d/l-lactic and acetic acids. Bread performance was evaluated by specific volume, slice shape, crumb structure and firmness, crust and crumb colour, pH, total titratable acidity, and d/l-lactic and acetic acids, phytate, and lower myo-inositol phosphate contents. The sourdough breads showed similar technological quality to the control sample, with the exception of specific bread volume (decreased from 2.46 to 2.22 mL/g) and crumb firmness (increased from 2.61 to 3.18 N). Sourdough inoculated with bifidobacteria significantly increased the levels of organic acids in fermented dough and bread. The Bifidobacterium strain contributed to the fermentation process, increasing phytate hydrolysis during fermentation owing to the activation of endogenous cereal phytase and its own phytase, resulting in bread with significantly lower phytate levels (from 7.62 to 1.45 μmol/g of bread in dry matter). The inclusion of sourdough inoculated with bifidobacteria made possible the formulation of whole wheat bread with positive changes in starch thermal properties and a delay and decrease in amylopectin retrogradation.     

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.     

Effect of flaxseed flour addition on physicochemical and sensory properties of functional bread

The importance of polyunsaturated fatty acids (PUFA) in health and nutrition is well recognised. Flaxseed (Linum usitatissimum) has recently gained a lot of attention as functional food because of its unique nutrient profile. In the present work efforts were made to develop omega-3 enriched functional bread using raw and roasted ground flaxseed flour. Initially optimisation of each bread ingredient viz., salt, sugar, and shortening, GMS, yeast and water was carried out on the basis of sensory overall acceptability score. The standardised bread was incorporated with raw and roasted ground flaxseed (5, 10, and 15 g/100 g) flour. The effect of flaxseed incorporation on bread dough rheology parameters viz., dough stickiness and water absorption was studied. Increase in water absorption and dough stickiness was observed with increased flaxseed level. Further breads were evaluated for sensory parameters, colour and texture. The crumb softness increased with increase in flaxseed level. Bread was optimised at 10(g/100 g) flaxseed level based on sensory evaluation.