Improvement of the quality of whole wheat bread by supplementation of xylanase from Aspergillus foetidus

Quality attributes and functional properties of whole wheat bread baked from frozen dough with the addition of enzymes and hydrocolloids

BACKGROUND

The increased demand for healthy and standardized bread has led to a demand for an efficient and promising dough improver, of natural origin, to reduce the deterioration of whole wheat bread baked from frozen dough caused by the high levels of dietary fiber and by freezing treatment. In this study, the combined effects of xylanase (XYL), lipase (LIP), and xanthan gum (XAN) on the quality attributes and functional properties of whole wheat bread baked from frozen dough were evaluated.

RESULTS

The optimal combination, which contained XYL (0.12 g kg-1 ), LIP (0.25 g kg-1 ), and XAN (3.1 g kg-1 ), was obtained using response surface methodology (RSM). The addition of the optimal combination endowed frozen dough bread with a higher specific volume, softer texture, better brown crumb color, and greater overall acceptability. The optimal combination had no adverse impact on the volatile organic compounds (VOCs) of frozen dough bread. In terms of the functional properties of bread, the water-holding capacity (WHC), oil-holding capacity (OHC), and swelling capacity (SWC) of dietary fiber in frozen dough bread decreased in the presence of the optimal combination, whereas the glucose adsorption capacity (GAC) did not affect them. Correspondingly, the in vitro digestive glucose release was not significantly different between the control group and the optimal combination group after frozen storage.

CONCLUSION

The optimal combination could improve the quality attributes and functional properties of whole wheat bread baked from frozen dough effectively, thereby increasing consumption. © 2023 Society of Chemical Industry.

High-Molecular-Weight Xylanase from B. pumilus US570 Strain: Purification, Characterization and Application in Banana and Orange Peels Hydrolysis and Breadmaking

New xylanase (XylUS570) was purified from the Bacillus pumilus US570 strain. It has a molecular mass of about 232 kDa. This is the first report on the highest molecular weight monomeric xylanase produced by bacteria. The optimum pH and temperature recorded for enzyme activity were 7 and 55 °C, respectively with a half-life time of 10 min at 60 °C. At 37 °C, the enzyme retains more than 50% of its activity at a pH ranging from 6 to 9.5 for 24 h. The XylUS570 exhibited a high activity on xylan, but no activity was detected for cellulosic substrates. The Vmax and Km values exhibited by the purified enzyme on beechwood xylan were 37.05 U mL-1 and 4.189 mg mL-1, respectively. The XylUS570 was used in banana and orange peels hydrolysis and showed potential efficiency to liberate reducing sugars. It could be a good candidate for bio-ethanol production from fruit waste. The purified enzyme was used also as an additive in breadmaking. A decrease in water absorption, an increase in dough rising and improvements in volume and specific volume of the bread were recorded.

Interaction of wheat bran dietary fiber-gluten protein affects dough product: A critical review

Wheat bran dietary fiber (WBDF) is an emerging food additive used for improving the nutritional value of dough products, albeit its adverse effects cannot be ignored. The dilution effect, mechanical shear effect, competitive water absorption, and steric hindrance of WBDF, as well as the non-covalent binding between WBDF and gluten protein, are considered the key mechanisms underlying the WBDF-gluten protein interaction. However, current studies on the interaction are mostly limited to the impact of the interaction on gluten protein and are rarely focused on the quality of products. Therefore, the effects of the interaction on the structural characteristics and aggregation behavior of gluten protein and multiple involved mechanisms are discussed in this review. On this basis, these changes are systematically related to the gluten network structure, dough properties, and product quality. Mitigation measures corresponding to negative impacts also need to be elaborated to guide and standardize the production and development of dough products containing WBDF.

DSEMR: A database for special environment microorganisms resource and associating them with synthetic biological parts

Special environmental microorganisms are considered to be of great industrial application value because of their special genotypes, physiological functions and metabolites. The research and development of special environmental microorganisms will certainly bring about some innovations in biotechnology processes and change the face of bioengineering. The Special Environmental Microbial Database (DSEMR) is a comprehensive database that provides information on special environmental microbial resources and correlates them with synthetic biological parts. DSEMR aggregates information on specific environmental microbial genomes, physiological properties, culture media, biological parts, and metabolic pathways, and provides online tool analysis data, including 5268 strains from 620 genera, 31 media, and 42,126 biological parts. In short, DSEMR will become an important resource for the study of microorganisms in special environments and actively promote the development of synthetic biology.

Combined Effects of Particle Size and Dough Improvers on Improving the Quality of Purple-Colored Whole Wheat Bread

Consumers' interest in healthy products is increasing. However, the production of excellent-quality whole wheat bread (WWB) faces challenges due to the reduced gluten functionality and varied particle sizes of whole wheat flour (WWF). This study aimed to explore the enhancement of purple-colored WWB quality by controlling the particle size of WWF and using dough improvers. Six purple-colored WWFs were obtained using an ultra-centrifugal mill with different sieve openings (0.5 and 1.0 mm) and rotor speeds (6000, 10,000, and 14,000 rpm). The average particle diameter (d50) of the smaller particle size group (S) and the larger particle size group (L) based on the sieve opening ranged from 115 to 258 μm and 294 to 492 μm, respectively. Group S demonstrated higher water absorption, damaged starch, and gluten strength compared to group L. Additionally, group S exhibited a greater bread volume and height compared to group L. Among the tested dough improvers (vital wheat gluten, vitamin C, enzymes, and emulsifiers), vital wheat gluten was the most effective in improving the quality of purple-colored WWB. The improvement effect was significantly greater in group S than in group L. These findings suggest that controlling the particle size of purple-colored WWFs and utilizing dough improvers can result in superior-quality WWB.

A novel cold-active GH8 xylanase from cellulolytic myxobacterium and its application in food industry

Although xylanase have a wide range of applications, cold-active xylanases have received less attention. In this study, a novel glycoside hydrolase family 8 (GH8) xylanase from Sorangium cellulosum with high activity at low temperatures was identified. The recombinant xylanase (XynSc8) was most active at 50 °C, demonstrating 20% of its maximum activity and strict substrate specificity towards beechwood and corncob xylan at 4 °C with V_max values of 968.65 and 1521.13 μmol/mg/min, respectively. Mesophilic XynSc8 was active at a broad range of pH and hydrolyzed beechwood and corncob xylan into xylooligosaccharides (XOS) with degree of polymerization greater than 3. Moreover, incorporation of XynSc8 (0.05-0.2 mg/kg flour) provided remarkable improvement (28-30%) in bread specific volume and textural characteristics of bread compared to commercial xylanase. This is the first report on a novel cold-adapted GH8 xylanase from myxobacteria, suggesting that XynSc8 may be a promising candidate suitable for bread making.

Characterization and application of a novel xylanase from Halolactibacillus miurensis in wholewheat bread making

The presence of arabinoxylan in wholewheat flour affects its quality significantly. Here, an efficient arabinoxylan hydrolytic enzyme, Hmxyn, from Halolactibacillus miurensis was identified and heterologously expressed in pichia pastoris. Moreover, its relevant properties, including potential application in the wholewheat bread were evaluated. Recombinant Hmxyn exhibited maximal activity at 45°C and pH 6.5, and was stable at mid-range temperature (<55°C) and pH (5.5–8.0) conditions. Hmxyn had a clear hydrolysis effect on wheat arabinoxylan in dough and caused the degradation of the water-unextractable arabinoxylan, which increased the content of wheat soluble arabinoxylan of dough. The fermentation characteristics results and microstructure analysis revealed that Hmxyn improved the organizational structure and air holding capacity of fermented dough, thus promoting the dough expansion. Baking experiments further showed that Hmxyn significantly increased specific volume- and texture-linked properties of wholewheat breads. This study indicates the application potential of Hmxyn in the preparation of wholewheat bread.

Effect of Xylanase and Pentosanase Enzymes on Dough Rheological Properties and Quality of Baguette Bread

The wheat flour baguette bread is one of the most important foods throughout the world. Therefore, improving the quality of this type of white bread has always been of interest. In this study, the effect of xylanase and pentosanase enzymes on the rheological properties of dough and baguette bread characteristics was investigated. Adding xylanase and/or pentosanase had led to improve rheological properties of the dough. Using 0.2 gr pentosanase in 100 g flour significantly strengthened the gluten network of the dough. Also, this treatment had the lowest extensibility and the highest resistance ratio number. The treatment containing 0.6 g xylanase and 0.1 g pentosanase in 100 g flour had a higher moisture content on the first, third, and fifth days of storage time. Regarding the color of the crust of the produced bread, it was found that the addition of both enzymes at higher levels, especially in enzyme mixtures, decreased the brightness of the bread crust. Due to the organoleptic features of breads, adding xylanase and pentosanase enzymes could improve the volume and crumb texture of the bread, but no significant difference was observed in baking uniformity, physical shape, taste, and odor of bread crumbs. In conclusion, the findings in this study indicated that the type of enzymes added and enzyme levels affected dough rheology, bread properties, and quality of the baguette bread significantly.

Dietary fiber in bakery products: Source, processing, and function

Bakery products are prevalently consumed foods in the world, and they have been regarded as convenient dietary vehicles for delivering nutritive ingredients into people's diet, of which, dietary fiber (DF) is one of the most popular items. The food industry attempts to produce fiber-enriched bakery products with both increasing nutritional value and appealing palatability. As many new sources of DFs become available, and consumers are moving towards healthier diets, studies of using these DFs as functional ingredients in baked goods are becoming vast. Besides, the nutrition value of DF is commonly accepted, and many investigations have also revealed the health benefits of fiber-enriched bakery products. Thus, this chapter presents an overview of (1) trends in supplementation of DF from various sources, (2) impact of DF on dough processing, quality and physiological functionality of bakery products, and (3) technologies used to improve the compatibility of DF in bakery products.

Arabinoxylans as Functional Food Ingredients: A Review

The health benefits of fibre consumption are sound, but a more compressive understanding of the individual effects of different fibres is still needed. Arabinoxylan is a complex fibre that provides a wide range of health benefits strongly regulated by its chemical structure. Arabinoxylans can be found in various grains, such as wheat, barley, or corn. This review addresses the influence of the source of origin and extraction process on arabinoxylan structure. The health benefits related to short-chain fatty acid production, microbiota regulation, antioxidant capacity, and blood glucose response control are discussed and correlated to the arabinoxylan’s structure. However, most studies do not investigate the effect of AX as a pure ingredient on food systems, but as fibres containing AXs (such as bran). Therefore, AX’s benefit for human health deserves further investigation. The relationship between arabinoxylan structure and its physicochemical influence on cereal products (pasta, cookies, cakes, bread, and beer) is also discussed. A strong correlation between arabinoxylan’s structural properties (degree of branching, solubility, and molecular mass) and its functionalities in food systems can be observed. There is a need for further studies that address the health implications behind the consumption of arabinoxylan-rich products. Indeed, the food matrix may influence the effects of arabinoxylans in the gastrointestinal tract and determine which specific arabinoxylans can be included in cereal and non-cereal-based food products without being detrimental for product quality.

Clean-label techno-functional ingredients for baking products - a review

The increased awareness of consumers regarding unfamiliar labels speeded up the ongoing clean label trend. As baking products are widely consumed worldwide, the reduction of non-natural baking aids and improvers is of great interest for consumer's health but also representing a big challenge for food industries. Thus, this paper aims at describing new techno-functional clean label ingredients for baked products and their production processes conditions. Firstly, it includes ingredients such as sustainable protein sources, fat replacers and leavening alternatives. Then, it addresses new process alternatives for producing baking ingredients with natural claim as well as current concepts as the natural fermentation. In particular, molecular and functional modifications of the flour are discussed regarding malting and dry heat treatments. By being considered as green and emerging technologies that improve flour functionality, the resulting ingredients can replace additives. Changes in quality and technological attributes of breads and cakes will be discussed as a consequence of the partial to total replacement of conventional ingredients. This paper provides new alternatives for the baking industry to meet the demand of a growing health-concerned population. In addition, it focused on opening up new possibilities for the food industry to go in line with the consumers' expectations.

Impact of celluloses and pectins restrictions on gluten development and water distribution in potato-wheat flour dough

The addition of potato to wheat flour extends the nutritional values of bread. However, the adverse effects mediated by high dietary fiber in potato flour could affect the formation of gluten matrix. The water dynamics and distribution determined by the Low field nuclear magnetic resonance (LF-NMR) demonstrated a competitive water binding of dietary fiber, resulting in the partial dehydration and conformational changes of gluten protein complexes. Besides, the microstructure of the dough characterized by Scanning electron microscope (SEM) suggested that the insoluble cellulose could block the continuity of gluten from the spatial position, thereby negative affecting the mechanical properties of the dough. In our study, addition of cellulase and/or pectinase apparently mitigated the gluten aggregation and dehydration, contributing to the formation and the continuity of the three-dimensional gluten network. As a consequence, the specific volume of the bread was increased by 40.2%, and the hardness was reduced by 64.48%.

Fungal xylanolytic enzymes: Diversity and applications

As important polysaccharide degraders in nature, fungi can diversify their extensive set of carbohydrate-active enzymes to survive in ecological habitats of various composition. Among these enzymes, xylanolytic ones can efficiently and sustainably degrade xylans into (fermentable) monosaccharides to produce valuable chemicals or fuels from, for example relevant for upgrading agro-food industrial side streams. Moreover, xylanolytic enzymes are being used in various industrial applications beyond biomass saccharification, e.g. food, animal feed, biofuel, pulp and paper. As a reference for researchers working in related areas, this review summarized the current knowledge on substrate specificity of xylanolytic enzymes from different families of the Carbohydrate-Active enZyme database. Additionally, the diversity of enzyme sets in fungi were discussed by comparing the number of genes encoding xylanolytic enzymes in selected fungal genomes. Finally, to support bio-economy, the current applications of fungal xylanolytic enzymes in industry were reviewed.

Biochemical characterization of a GH10 xylanase from the anaerobic rumen fungus Anaeromyces robustus and application in bread making

Anaeromyces robustus is an anaerobic rumen microorganism which can produce plant cell wall degrading enzymes. In this study, a new GH10 xylanase gene xylAr10 from A. robustus was identified, cloned and expressed in Pichia pastoris GS115. The recombinant protein ArXyn10 was characterized after being purified by Ni-NTA. The optimal pH and temperature of ArXyn10 was determined at 5.5 and 40 °C, respectively. ArXyn10 was stable at the pH range of 4.0-8.0, and could maintain high stability from 35 to 45 °C. The hydrolysis products released from beechwood xylan by ArXyn10 showed chromatographic mobility similar to xylobiose and xylotriose according to thin-layer chromatography analysis. It was shown that the addition of 7.5 mg of ArXyn10 in 100 g high-gluten wheat flour during bread making could increase the reducing sugar content by 10.80%, indicating that xylo-oligosaccharides were produced. With the addition of ArXyn10, the hardness and chewiness of the bread decreased and the quality was improved. The new discovered xylanase ArXyn10 have potential application prospect in bread making.

Paecilomyces variotii xylanase production, purification and characterization with antioxidant xylo-oligosaccharides production

Paecilomyces variotii xylanase was, produced in stirred tank bioreactor with yield of 760 U/mL and purified using 70% ammonium sulfate precipitation and ultra-filtration causing 3.29-fold purification with 34.47% activity recovery. The enzyme purity was analyzed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) confirming its monomeric nature as single band at 32 KDa. Zymography showed xylan hydrolysis activity at the same band. The purified enzyme had optimum activity at 60 °C and pH 5.0. The pH stability range was 5-9 and the temperature stability was up 70 °C. Fe²⁺and Fe³⁺ exhibited inhibition of xylanase enzyme while Cu²⁺, Ca²⁺, Mg²⁺ and Mn²⁺ stimulated its activity. Mercaptoethanol stimulated its activity; however, Na₂-EDTA and SDS inhibited its activity. The purified xylanase could hydrolyze beechwood xylan but not carboxymethyl cellulose (CMC), avicel or soluble starch. Paecilomyces variotii xylanase K_m and V_max for beechwood were determined to be 3.33 mg/mL and 5555 U/mg, respectively. The produced xylanase enzyme applied on beech xylan resulted in different types of XOS. The antioxidant activity of xylo-oligosaccharides increased from 15.22 to 70.57% when the extract concentration was increased from 0.1 to 1.5 mg/mL. The enzyme characteristics and kinetic parameters indicated its high efficiency in the hydrolysis of xylan and its potential effectiveness in lignocellulosic hydrolysis and other industrial application. It also suggests the potential of xylanase enzyme for production of XOS from biomass which are useful in food and pharmaceutical industries.

The Effects of Transglutaminase and Refrigerated Storage on the Physicochemical Properties of Whole Wheat Dough and Noodles

This study investigated the effects of transglutaminase (TG) concentrations (0, 0.1% and 1%) on the physicochemical properties of whole wheat dough (WWD) and noodles (WWN) during refrigerated storage (0, 1, 2, and 3 days). The yield, ferulic acid (FA) content, molecular weight (Mw), and apparent viscosity (AV) of water extractable arabinoxylan (WEAX) from refrigerated WWDs were analysed. The WEAX yield and FA tended to increase with refrigerated storage, while the Mw decreased. WEAX FA of from WWD with TG tended to be smaller than the control during refrigeration. The AV for all WEAXs gradually decreased during refrigeration. The TG concentration effects on WWD resistance to extension and extensibility and the WWN cooking properties and texture profile analysis (TPA) were studied. The water absorption and swelling index tended to decrease in WWNs with TG depending on refrigeration time compared to the control samples. The TPA results showed that WWNs with TG were significantly harder than the control after two days of refrigeration. This study demonstrated that TG affected not only WWD composition but also WWN physical properties during refrigerated storage.

Frozen steamed breads and boiled noodles: Quality affected by ingredients and processing

Chinese steamed breads (CSB) and noodles are staple foods for many people. The production of frozen steamed products and boiled noodles has kept increasing. This is due to the increasing demand of ready-to-eat frozen food products from the market. Frozen storage significantly increases the self-life of the products and reduces the production costs. On the other hand, the freezing and frozen storage lead to quality loss of the frozen products. This review summarizes effects of freezing and frozen storage on diverse quality attributes (e.g., structural and textural properties) of frozen northern-type steamed breads and boiled noodles. Food safety of the frozen products related to the COVID-19 pandemic is discussed. To counteract the quality loss of the frozen products, suitable processing methods, selection of basic ingredients and uses of various food additives can be done. Research gaps to improve the textural, cooking and nutritional quality of frozen CSB and noodles are suggested.

Influence of Buckwheat and Buckwheat Sprouts Flours on the Nutritional and Textural Parameters of Wheat Buns

In recent years, food products manufactured with buckwheat and sprouts flours have attracted widespread interest due to their high nutritional value with various health benefits, becoming more and more popular. The purpose of this study was to assesses the influence of buckwheat and sprouts flours on the nutritional, sensorial and textural characteristics on the final baked products. In order to achieve these goals, methods like HPLC-RID (High-Perfomance Liquid Chromatography with Refractive Index Detection), aluminum chloride colorimetric assay, Folin-Ciocalteu and 1,1-Diphenyl-2-picrylhydrazyl (DPPH) were used to determine fructose, glucose, sucrose, maltose; total flavonoids, total phenols and antioxidant activity. Sensorial analysis was realized by using hedonic test and texture profile was performed on a CT 3 Texture Analyzer. The results proved that wheat flour could be successfully replaced by 20% buckwheat and 10% sprouts flours, respectively, improving their nutritional value, without negative influence on texture parameters and sensorial features. The obtained buns were accepted by consumers with a total hedonic score of 9.1 and 8.7, respectively. Hardness, gumminess and adhesiveness were improved by using Magimix improver, meanwhile cohesiveness, springiness, gumminess and adhesiveness were improved by using guar gum.

Effect of chemical oxidizers and enzymatic treatments on the baking quality of doughs formulated with five Canadian spring wheat cultivars

For many years, the baking industry has been using chemical improvers as a way for compensating for flour quality variation due to growing conditions or wheat cultivar. However, the replacement of chemical dough improvers with natural ingredients or processing aids (i.e. enzymes) allows for the production of 'cleaner label' products. In the present research, dough and bread properties (mixing time, oven rise, loaf volume, crumb firmness and C-cell parameters) were analysed as a function of wheat cultivar (Glenn, Harvest, Lillian, CDC Plentiful and Stettler), additive-type (ascorbic acid, azodicarbonamide, glucose oxidase and fungal xylanase) and concentration. Overall, the cultivar Glenn appeared to have improved baking performance relative to the other cultivars, regardless of the additive and additive concentration. On the other hand, Stettler showed poorer baking quality and performance even with the addition of oxidizers and enzymes in relation to the control. The concentration of additive was found to have little or no effect on improving baking properties within each cultivar. Enzymes had similar or better performance than oxidizers in most cases.

Impact of the fermentation broth of Ganoderma lucidum on the quality of Chinese steamed bread

The potential of fermentation broth of Ganoderma lucidum (FB_G) in improving the quality of Chinese steamed bread (CSB) was firstly evaluated. The sensory quality scores of CSB treated by FB_G are significantly higher than that of CSB in the control, and texture profile analysis also indicates the increase of CSB hardness and chewiness caused by FB_G. Observation on micro-structure of CSB shows that formation of larger pores and expansion of starch granules are the important reasons for the improvement of CSB specific volume (vol_S), and granule expansion is due to that gluten network distributed in CSB is destroyed as a result of cross-linkage of flour proteins catalyzed by laccase, which makes starch granules releasing from the network easily contact with steam or other enzymes during the proofing and steaming of dough. Moreover, FB_G contains amylases which not only convert amylopectin to amylose, but also degrade starch to glucose, maltose and polysaccharides, correspondingly resulting in changes of amylose/amylopectin (Ae/An) ratio of flour and CSB vol_S, and the latter is because more CO₂ produced by the yeast during CSB making leads to the larger pore area in crumb. Both hardness and chewiness are determined by the comprehensive effect of protein cross-linkage, Ae/An ratio and vol_S change, and this viewpoint gives a logical explanation for the effects of 0.025–0.10 ml/g of FB_G on hardness and chewiness of CSB.

Effect of combining additional bakery enzymes and high pressure treatment on bread making qualities

Various enzymes are added to dough to improve the quality. Two enzymes are α-amylase and hemicellulase (bakery enzymes), whose substrates are damaged starch and insoluble dietary fiber, respectively. They improve the formation of gluten networks in the dough, resulting in a higher specific loaf volume (SLV). The use of high-pressure treatment has also increased as a substitute for heat treatment and various products are being processed utilizing high-pressure treatment. This study investigated the effect of combing bakery enzyme and high-pressure treatment on dough qualities. The optimal concentration of bakery enzymes and high-pressure level were determined using response surface methodology and optimization technique. Bread dough was prepared by the optimal condition, 0.20% of bakery enzyme and 43 MPa of high-pressure treatment, and the bread dough was then baked. Optimal combining bakery enzyme and high-pressure treatment drastically improved bread making qualities such as increased SLV, higher concentrations of reducing sugar, and lower concentrations of damaged starch and insoluble dietary fiber compared to the control and to those that were only treated with bakery enzymes or high-pressure treatment, respectively. In addition, the bread with both bakery enzymes and high-pressure treatment showed improved micro structure in the crumb and maintained freshness longer.

Application of rich in β-glucan flours and preparations in bread baked from frozen dough

This study aims to define the changes in the quality of bakery products depending on the β-glucan source and its contribution using bake-off technology. The examined bread was enriched with a 10% addition of oat flour, barley flour, oat fibre preparation, and barley fibre preparation. Bread was tested for rheological parameters, baking performance, hardness and springiness, water content, specific volume, porosity, crust and crumb colour, and β-glucan content. In the executed research, the adverse effect of this component on the formation of gluten network and hardness of the crumb was observed. In the double compression test, it was shown that the highest hardness on the day of baking was characterized by the bread with the addition of barley preparation. The fastest rate of staling was observed in the bread with additional barley flour that was affected by the highest amount of β-glucan. A significant decrease of the β-glucan level was also found during the technological bake-off process, which can be explained by the activity of enzymes.

Effect of β-endoxylanase and α-arabinofuranosidase enzymatic hydrolysis on nutritional and technological properties of wheat brans

Wheat bran (WB) was treated using xylanase and arabinofuranosidase from Thermotoga maritima and added to steamed breads on 15% flour weight basis. The antioxidant capacity and water and oil retention capacity of brans were increased while their soluble xylooligosaccharides and phenolic acids content were increased. Two enzymes treatment was found to be more effective in decreasing the resistance to extension, softening degree, water absorption and development time, and in increasing the extensibility, stability time, porosity and sensorial characteristics of the steamed breads. Two enzymes treatment had significantly (P < 0.05) greater specific volume, springiness and cohesiveness and lower crumb firmness, gumminess, chewiness than single enzyme treatment. All results highlighted that combination of xylanase and arabinofuranosidase can improve the degrees hydrolysis of WB and its soluble AX xylooligosaccharides produced, having a synergetic effect on the dough rheology and nutritional and quality characteristics of steamed bread.

The Addition of α-cyclodextrin and γ-cyclodextrin Affect Quality of Dough and Prebaked Bread During Frozen Storage

The effects of the addition of 0–3.0 wt% α-cyclodextrin (α-CD) and γ-cyclodextrin (γ-CD) on the quality of wheat flour as well as the texture and the aging of prebaked bread were evaluated. The addition of α-CD and γ-CD increased the ability of wheat flour to absorb water and shortened the times of dough formation and stabilization. Amylase activity slightly increased after using 2.0 and 3.0 wt% of α-CD and γ-CD, respectively. Moreover, the addition of α-CD and γ-CD increased the fermentation height and gas retention ability of dough. Dough samples containing 2.0 wt% α-CD and 3.0 wt% γ-CD showed the highest fermentation heights and gas retention volumes, respectively. Dough gas production increased with the addition of γ-CD. Gas production by dough samples containing more than 2.0 wt% α-CD exceeded that by samples in the control group. The results of the texture crumb of bread and specific volume tests revealed that the addition of 2.0 wt% α-CD and 3.0 wt% γ-CD reduced bread hardness and increased bread elasticity, resilience, and specific volume. The optimal α-CD and γ-CD contents were identified as 2.0 wt% and 3.0 wt%, respectively. The addition of 2.0 wt% α-CD and 3.0 wt% γ-CD delayed the aging of prebaked bread and reduced the hardness of prebaked bread during different weeks of storage, which may be due to decreasing the melting enthalpy of starch crystals. This work elucidated the mechanisms underlying the effects of CD addition on prebaked bread quality.

Optimization of enzymes addition to improve whole wheat bread making quality by response surface methodology and optimization technique

The functional ingredients in whole wheat flour, such as dietary fiber, vitamins, and minerals, have beneficial health effects. However, the excessive amount of dietary fiber in whole wheat flour inhibits gluten network formation and diminishes bread making qualities (BMQ). Adding appropriate amounts of enzymes, α-amylase (AM) and hemicellulase (HC), could be a solution to these problems. In this study, response surface methodology (RSM) created a response surface model and Solver (Excel add-in software) calculated the optimal amounts of the enzymes. Adding optimum concentrations of AM and HC drastically improved BMQ (gas retention of dough, specific loaf volume, and bread staling) of whole wheat flour dough and bread compared to whole wheat flour dough and bread without the enzymes. These results showed that combining RSM and Solver was an effective and reasonably easy method that determines optimal concentrations of enzymes to obtain the highest quality bread using whole wheat flour.

Engineered GH11 xylanases from Orpinomyces sp. PC-2 improve techno-functional properties of bread dough

BACKGROUND

Endo-1,4-β-xylanases have marked hydrolytic activity towards arabinoxylans. Xylanases (xynA) produced by the anaerobic fungus Orpinomyces sp. strain PC-2 have been shown to be superior in specific activity, which strongly suggests their applicability in the bakery industry for the processing of whole-wheat flour containing xylans. In the present study, two xylanases from this source, the small wild-type xylanase SWT and the small mutant xylanase SM2 (V108A, A199T), were expressed in Escherichia coli, purified, characterized, tested for their ability to hydrolyze whole-wheat flour and applied in dough processing.

RESULTS

Both purified SM2 and SWT showed high specific activity against oat spelt xylan and wheat arabinoxylan, exhibiting maximum activity at pH 3-7 and 60 °C. SM2 was more thermostable than SWT, which suggests that the mutations enhanced its stability. Both SWT and SM2 were able to hydrolyze whole-wheat flour, and evaluation of their applicability in dough processing by the sponge method indicated that use of these enzymes increased dough volume by 60% and reduced texture hardness by more than 50%, while gumminess and chewiness were reduced by 40%.

CONCLUSION

The recombinant xylanases showed potential for application in bakery processing and can improve techno-functional properties in sponges. © 2018 Society of Chemical Industry.

Resistant starch: effect on rheology, quality, and staling rate of white wheat bread

The effect of the partial substitution (0, 10, 15, and 20%) of wheat flour with resistant starch (RS) on dough rheology and structure, and on the quality and staling rate of bread was evaluated. The results from farinograph, extensograph, alveograph, oscillatory rheological tests, and from confocal laser scanning microscopy, indicated that the substitution up to 15% of flour with RS slightly affected the dough structure, weakening it through dilution of gluten protein. Bread made with 15% of RS had specific volume, crumb moisture, and firmness values similar to those of the control bread (without RS), indicating very good quality. During storage, the RS breads had higher crumb moisture, lower firmness, and a lower retrogradation rate than the control bread. The lower retrogradation rate, in conjunction with the higher crumb moisture and high water-retention capacity of RS, was responsible for lower crumb firmness in bread containing up to 15% RS. Using wheat flour of high quality helped to minimize the deleterious effect of RS on the dough and provided high-fiber bread with high quality and low staling.

A family 30 glucurono-xylanase from Bacillus subtilis LC9: Expression, characterization and its application in Chinese bread making

A GH30-8 endoxylanase was identified from an environmental Bacillus subtilis isolate following growth selection on aspen wood glucuronoxylan. The putative endoxylanase was cloned for protein expression and characterization in the Gram-positive protease deficient protein expression host B. subtilis WB800. The extracellular activity obtained was 55 U/mL, which was 14.5-fold higher than that obtained with the native species. The apparent molecular mass of BsXyn30 was estimated as 43 kDa by SDS-PAGE. BsXyn30 showed an optimal activity at pH 7.0 and 60 °C. Recombinant BsXyn30 displayed maximum activity against aspen wood xylan, followed by beechwood xylan but showed no catalytic activity on arabinose-substituted xylans. Analysis of hydrolyzed products of beechwood xylan by thin-layer chromatography and mass spectroscopy revealed the presence of xylooligosaccharides with a single methyl-glucuronic acid residue. BsXyn30 exhibited very low activity for hydrolysis xylotetraose and xylopentaose, but had no detectable activity against xylobiose and xylotriose. Using BsXyn30 as an additive in breadmaking, a decrease in water-holding capacity, an increase in dough expansion as well as improvements in volume and specific volume of the bread were recorded. Thus, the present study provided the basis for the application of GH30 xylanase in breadmaking.

The effects of certain enzymes on the rheology of dough and the quality characteristics of bread prepared from wheat meal

This study was carried out to evaluate the effects of amyloglucosidase, glucose oxidase, hemicellulase (mainly consist of endo-1,4-β-xylanase), cellulase, lipase, and the combination of phospholipase and hemicellulase (phospholipase + hemicellulase) on the extensographic properties of dough and the quality characteristics of bread prepared from wheat meal. The enzymes were added separately in two different amounts. The addition of glucose oxidase (at 0.0003-0.001%) caused a significant decrease in the resistance to extension, ratio of resistance to extensibility and energy values of the wheat meal dough compared with the control dough. The addition of hemicellulase (at 0.001-0.005%) and phospholipase + hemicellulase (at 0.0006-0.0009%) also improved the wheat meal dough rheology by reducing the resistance to extension and the ratio of resistance to extensibility. Glucose oxidase (at 0.0003-0.001%), hemicellulase (at 0.001-0.005%) and phospholipase + hemicellulase (at 0.0006-0.0009%) addition improved the specific volume of wheat meal bread compared with the control bread. Increasing the dosage of glucose oxidase from 0.0003 to 0.001% caused a further increase in the specific volume of wheat meal bread. The addition of hemicellulase (at 0.001-0.005%) caused a significant decrease in the baking loss and an increase in the moisture content of wheat meal bread compared with the control bread. The addition of amyloglucosidase (at 0.000875-0.001%), lipase (at 0.0002-0.001%) and cellulase (at 0.0003-0.0005%) did not considerably affected the dough rheological and the quality characteristics of wheat meal bread.

Optimization of additive content and their combination to improve the quality of pure barley bread

The objective of this study was to model the influence of pregelatinized OSA starch (OSA), wheat gluten (Gl) and xylanase (Xyl) on breadmaking potential of barley flour by using response surface methodology. Addition of these ingredients had significant effect on specific bread volume, crust and crumb lightness, crumb texture, average cell size and crumb density. OSA showed the most pronounced effect on specific bread volume, average cell size, crumb density and hardness. Interaction between OSA and Gl, as well as Gl and Xyl, respectively, increased and decreased the specific bread volume and crumb chewiness, while the interaction between OSA and Xyl decreased the specific volume decrease and increased crumb chewiness. An optimal barley bread formulation appeared to be the one containing 9.68% OSA, 2.0% Gl and 4.51 g/100 kg Xyl. This optimal barley bread formulation predicted an increment of 14-28% in volume and a decrease of 105-217% in crumb chewiness in comparison to formulations containing medium amounts of improvers (1% Gl, 5% OSA, 2.5 g/100 kg Xyl).

The effect of pentosanase on the solubilisation and degradation of arabinoxylan extracted from whole and refined wheat flour

BACKGROUND

The quality improvement capability of pentosanase (Pn) for whole-wheat Chinese steamed bread (CSB) is not as efficient as that for refined CSB. However, the underlying mechanism remains to be elucidated. In this work, water-extractable arabinoxylan (WEAX) and water-unextractable solids (WUS) were extracted from whole and refined wheat flour, and then treated with Pn under the conditions similar to CSB-making. Solubilisation and degradation of arabinoxylan (AX) caused by Pn treatment were determined.

RESULTS

WEAX from whole flour exhibited higher molecular weight than that from refined flour before and after the treatment with equivalent Pn. Compared with WUS from refined flour, WUS from whole flour had a much lower dissolution degree but the degradation of AX released from the WUS was more efficiently. Moreover, AX released from WUS for refined flour showed a higher Ara/Xyl ratio and the percentage of residual ferulic acid in WUS decreased more significantly.

CONCLUSION

The difference in quality improvement degree for Pn in whole-wheat and refined CSB might be mainly explained by its effect on WUS. That is, Pn contributed much more to the solubilisation of WUS from refined flour but provoked degradation predominantly on AX solubilised from WUS isolated from whole flour. © 2016 Society of Chemical Industry.