Use of chemical redox agents and exogenous enzymes to modify the protein network during breadmaking – A review

Effect of selenium, sonication, and combination of selenium and sonication treatments on potassium bromate, alloxan, and titanium dioxide in bread

Improvers such as potassium bromate, titanium dioxide, and bleaching agents are used in breadmaking despite existing bans. This research aimed to detect potassium bromate, alloxan (a by-product of bleaching agents), and titanium dioxide in bread samples from local automated and traditional bakeries. Bread samples prepared from local durum wheat flour underwent treatments (sonication, selenium, and selenium with sonication). X-ray Fluorescence (XRF) did not detect titanium dioxide, while potassium bromide (a reduced form of potassium bromate) was detected in all samples. UV-visible spectroscopy detected alloxan in 37.5 % of bakeries. Among all treatments, selenium and sonication effectively reduced potassium bromide, alloxan, and titanium dioxide concentrations in spiked (10,000 μg/g) bread samples. Dynamic Light Scattering (DLS) showed particle sizes over 100 nm in all treated samples, and Scanning Electron Microscopy (SEM) revealed the surface morphology structure of rough, flaky surfaces with compact particles for all treated prepared, and spiked samples, indicating no nanoparticle formation.

Catalase-induced changes in rheological properties and structure of wheat gluten proteins

This study investigates the impact of catalase (CAT) on the rheological properties of wheat gluten by analyzing CAT-induced structural changes in gluten proteins to uncover the mechanisms behind these modifications. The results showed that CAT significantly enhanced the storage modulus (G') and loss modulus (G″) of gluten while reducing creep strain and recovery strain. The most pronounced effects were observed with the addition of 250 U/g CAT for 30 min. CAT facilitated the formation of larger molecular weight aggregates in gluten proteins and increased the content of disulfide bonds and β-sheets, reaching 11.42 μmol/g and 45.78 %, respectively, after treatment with 250 U/g CAT for 30 min. These structural changes reduced the hydrophobic regions of gluten, lowered gluten extractability, and enhanced the compactness and stability of the gluten network. These effects substantially influenced the rheological behavior of wheat gluten, offering new insights and practical guidance for improving gluten-based products using CAT.

Encapsulation Efficiency of Electrosprayed Glucose Oxidase Capsules: Effect of the Drying Technique

Glucose oxidase (GOX) is widely used in bakery applications to improve dough rheology and bread quality. However, its direct addition to formulations limits its functionality due to premature enzymatic activity. This study used electrospraying to encapsulate GOX using chia mucilage and sodium alginate as biopolymeric wall materials. Three drying methods-critical point drying (CPD), Lyophilization/freeze-drying (LC), and oven drying (OD)-were compared to evaluate their impact on encapsulation efficiency (EE), enzymatic activity retention, and microstructural integrity. Our findings reveal that CPD preserved the porous structure of the microcapsules, minimizing enzymatic leakage and yielding the highest EE (70%). In contrast, LC induced ice crystal formation, disrupting the polymer network and leading to a moderate EE (27.43%), whereas OD resulted in extensive capsule shrinkage, causing significant enzyme loss (57.1%). The release kinetics of GOX during mixing were best described by the Korsmeyer-Peppas model (R2 = 0.999), indicating a non-Fickian diffusion mechanism influenced by polymer relaxation. These results demonstrate that drying technique selection plays a crucial role in encapsulated enzymes' stability and release behavior, providing new insights for optimizing enzyme delivery in bakery applications.

Morroniside interaction with poly (ADP-ribose) polymerase accentuates metabolic mitigation of alloxan-induced genotoxicity and hyperglycaemia: a molecular docking based in vitro and in vivo experimental therapeutic insight

The present study tends to evaluate the possible potential of bio-active Morroniside (MOR), against alloxan (ALX)-induced genotoxicity and hyperglycaemia. In silico prediction revealed the interaction of MOR with Poly (ADP-ribose) polymerase (PARP) protein which corroborated well with experimental in vitro L6 cell line and in vivo mice models. Data revealed the efficacy of MOR in the selective activation of PARP protein and modulating other stress proteins NF-κB, and TNF-α to initiate protective potential against ALX-induced genotoxicity and hyperglycaemia. Further, the strong interaction of MOR with CT-DNA (calf thymus DNA) analyzed through CD spectroscopy, UV-Vis study and ITC data revealed the concerted action of bio-factors involved in inhibiting chromosomal aberration and micronucleus formation associated with DNA damage. Finally, MOR does not play any role in microbial growth inhibition which often occurs due to hyperglycemic dysbiosis. Thus, from the overall findings, we may conclude that MOR could be a potential drug candidate for the therapeutic management of induced-hyperglycaemia and genotoxicity.Communicated by Ramaswamy H. Sarma.

Honey induces changes in the molecular structure and microstructure of gluten in wheat-rye sourdoughs

Chemical oxidizers and redox enzymes have traditionally been used to enhance the quality of baked goods. However, consumers now seek natural and clean-label ingredients, avoiding those with chemical-sounding names. Honey, a natural source of glucose oxidase (GOX), represents a promising alternative to purified enzymes for baking purposes. This study aimed to evaluate the effect of honey on the molecular structure and microstructure of gluten proteins in sourdough fermented by different lactic acid bacteria (LAB) strains. Four wheat-rye (1:1) sourdoughs were prepared, each supplemented with honey and inoculated with a different LAB strain. Additionally, two uninoculated doughs, one with honey (honey dough) and the other without (control dough), were prepared under identical conditions. Electronic paramagnetic resonance spectroscopy revealed the presence of hydrogen peroxide in honey solutions, indicating its role as an active source of GOX. Raman spectroscopy showed that honey addition altered the molecular structure of gluten by increasing the proportion of random coils at the expense of α-helix structures. This change is likely attributed to the competition between honey sugars and gluten proteins for water molecules in this system. Moreover, honey led to a decrease in the free sulfhydryl content of gluten compared to the control dough, suggesting an increase in disulfide crosslinking points. These enhanced protein-protein interactions were observed in scanning electron microscopy micrographs as a coarse gluten network composed of interconnected strands and fibrils. All LAB strains exhibited optimal acidification (pH < 4.3) in honey-supplemented sourdoughs, promoting the hydrolysis of gluten proteins into smaller fragments. Overall, honey-supplemented sourdoughs showed a gradual increase in the β-sheet content while decreasing the proportion of random coils over time. This trend suggests that the polypeptide fragments interacted through interchain hydrogen bonds, leading to a more ordered structure, which likely contributes to providing dough with good baking aptitude.

Effect of a Bacterial Laccase on the Quality and Micro-Structure of Whole Wheat Bread

The gluten protein content in whole-wheat flour is low, which affects the elasticity and viscosity of the dough. Enzymatic modification of the protein may result in a network that mimics gluten, which plays an important role in the processing of whole-wheat foods. In this study, the effects of Halomonas alkaliantartica laccase (LacHa) on the quality parameters of whole-wheat bread were investigated. The optimum dosage of LacHa was 4 U/100 g of whole-wheat flour. At this dosage, whole-wheat bread exhibited the best specific volume and optimum texture parameters. Laccase also extended the storage duration of whole-wheat bread. We analyzed the micro-structure of the dough to determine its gluten-free protein extractable rate and free sulfhydryl group content, and verify that LacHa mediates cross-linking of gluten-free proteins. The results demonstrated that the cross-linking of gluten-free protein by LacHa improves the texture of whole-wheat bread. As a flour improver, LacHa has great developmental and application potential in baked-food production.

Organic acids in bread-making affecting gluten structure and digestibility

Although wheat gluten has remarkable technological properties, it can induce adverse immune reactions in susceptible individuals, such as wheat allergy and celiac disease. Technological processing and some additives on bread formulation can modify gluten physicochemical structure, but the knowledge about the impacts on the digestibility and immunogenicity of gluten is limited. The present study aimed to study the effect of adding organic acids (acetic or ascorbic) on dough rheological properties and bread technological characteristics. In addition, breads were subjected to in vitro digestion and the digesta were analyzed by confocal microscopy, SDS-PAGE and ELISA immunoassay. Acetic acid resulted in a decrease in dough development time up to 44 % and a reduction in stability up to 20 %. Ascorbic acid, present in vinegar, on the other hand, increased elastic modulus (G') and resistance to extension of dough. After the in vitro digestion, SDS-PAGE indicated that protein degradation started in the gastric phase, with the generation of low molecular weight peptides. Accordingly, ELISA immunoassay suggested a great reduction in immunogenic gliadin content from oral to gastric phase. At the end of the intestinal phase, samples with ascorbic acid did not differ from the control, while vinegar addition indicated a reduction in gluten immunogenicity with a reduction of about 44 % in immunogenic gliadin content compared to the control. Results show a window of opportunity in the modulation of wheat bread formulation with reduced allergenicity, while maintaining the technofunctional properties.

Effect of radio frequency energy on buckwheat quality: An insight into structure and physicochemical properties of protein and starch

Radio frequency (RF) heating as an emerging technology is widely used to improve cereal-based food quality. To further investigate effects of RF treatment on buckwheat quality, structures and physicochemical properties of protein and starch in buckwheat were evaluated under various temperatures (80, 90, and 100 °C) and holding times (0, 5, and 10 min). Results showed that protein-starch complexes were reaggregated with the increases of RF heating temperature and time, as well as the values of R1047/1022, crystallinity, random coil, and α-helix significantly decreased, and the values of β-sheet obviously increased. Moreover, viscosities and rheological properties of buckwheat were reduced by the raised RF treatment intensity. Besides, the RF processing had a mostly positive effect on swelling power at low temperature of 30 °C, but contrary effect at high temperatures of 60 °C and 90 °C. However, changes of water solubility index, emulsifying capacity, and emulsion stability depended on the RF processing intensity. These results of the study suggested that buckwheat quality was affected by multiple RF treatment conditions, which can be tailored to develop a RF process having the potential to improve the function of buckwheat flour.

Changes in metabolic landscapes shape divergent but distinct mutational signatures and cytotoxic consequences of redox stress

Mutational signatures discerned in cancer genomes, in aging tissues and in cells exposed to toxic agents, reflect complex processes underlying transformation of cells from normal to dysfunctional. Due to its ubiquitous and chronic nature, redox stress contributions to cellular makeover remain equivocal. The deciphering of a new mutational signature of an environmentally-relevant oxidizing agent, potassium bromate, in yeast single strand DNA uncovered a surprising heterogeneity in the mutational signatures of oxidizing agents. NMR-based analysis of molecular outcomes of redox stress revealed profound dissimilarities in metabolic landscapes following exposure to hydrogen peroxide versus potassium bromate. The predominance of G to T substitutions in the mutational spectra distinguished potassium bromate from hydrogen peroxide and paraquat and mirrored the observed metabolic changes. We attributed these changes to the generation of uncommon oxidizing species in a reaction with thiol-containing antioxidants; a nearly total depletion of intracellular glutathione and a paradoxical augmentation of potassium bromate mutagenicity and toxicity by antioxidants. Our study provides the framework for understanding multidimensional processes triggered by agents collectively known as oxidants. Detection of increased mutational loads associated with potassium bromate-related mutational motifs in human tumors may be clinically relevant as a biomarker of this distinct type of redox stress.

Sonochemical Effects on the Preparation, Structure and Function of Gliadin-(-)-Epigallo-Catechin 3-Gallate Conjugates

It is essential to understand the mechanism of action of ultrasound synergistic free radical oxidation to promote covalent reactions between proteins and polyphenols. (-)-epigallo-catechin 3-gallate (EGCG) with rich bioactivity could be used to increase the functional properties of cereal protein-gliadin (GL). This study systematically explored the role of ultrasound treatment (US) on the binding mechanisms of GL and EGCG. Electrophoresis and high-performance liquid chromatography (HPLC) confirmed the greater molecular mass of the covalent complexes in the ultrasound environment. Quantitative analysis by the phenol content revealed that the ultrasound environment increased the EGCG content in the covalent complex by 15.08 mg/g of protein. The changes in the spatial structure of the proteins were indicated by Fourier infrared and ultraviolet spectroscopy. Additionally, scanning electron microscopy (SEM) and atomic force microscopy (AFM) found that US disrupted the aggregation of GL and the clustered structure of the covalent complexes. The results demonstrated that the water solubility of ultrasonic conjugates was significantly increased by 8.8-64.19%, the digestion rate was more efficient, and the radical scavenging capacity was twice that of GL. This research contributes to the theoretical basis for broadening the application of polyphenols in modifying protein.

Enhancing the Techno-Functionality of Pea Flour by Air Injection-Assisted Extrusion at Different Temperatures and Flour Particle Sizes

Industrial applications of pulses in various food products depend on pulse flour techno-functionality. To manipulate the techno-functional properties of yellow pea flour, the effects of flour particle size (small vs. large), extrusion temperature profile (120, 140 and 160 °C at the die) and air injection pressure (0, 150 and 300 kPa) during extrusion cooking were investigated. Extrusion cooking caused the denaturation of proteins and gelatinization of starch in the flour, which induced changes in the techno-functionality of the extruded flour (i.e., increased water solubility, water binding capacity and cold viscosity and decreased emulsion capacity, emulsion stability, and trough and final viscosities). In general, the large particle size flour required less energy input to be extruded and had higher emulsion stability and trough and final viscosities compared to the small particle size flour. Overall, among all of the treatments studied, extrudates produced with air injection at 140 and 160 °C had higher emulsion capacity and emulsion stability, making them relatively better suited food ingredients for emulsified foods (e.g., sausages). The results indicated air injection's potential as a novel extrusion technique combined with modification of flour particle size distribution and extrusion processing conditions to effectively manipulate product techno-functionality and broaden the applications of pulse flours in the food industry.

Recent Advances in the Study of Wheat Protein and Other Food Components Affecting the Gluten Network and the Properties of Noodles

Upon hydrating and mixing wheat flour, wheat protein forms a network that strongly affects the structure and physicochemical properties of dough, thus affecting the properties of noodles. Different approaches have been taken to alter the gluten network structure in order to control the dough properties. In the current review, we summarize the structure and function of wheat protein, including glutenin and gliadin, and describe food components that may affect noodle quality by interacting with wheat protein. In fact, the ratio of glutenin to gliadin is closely related to the viscosity of dough, and disulfide bonds also contribute to the gluten network formation. Meanwhile, wheat protein coexists with starch and sugar in wheat dough, and thus the nature of starch may highly influence gluten formation as well. Salts, alkali, enzymes and powdered plant food can be added during dough processing to regulate the extensional properties of wheat noodles, obtaining noodles of high quality, with improved sensory and storage properties. This review describes specific methods to reinforce the wheat protein network and provides a reference for improving noodle quality.

Recombinant Rice Quiescin Sulfhydryl Oxidase Strengthens the Gluten Structure through Thiol/Disulfide Exchange and Hydrogen Peroxide Oxidation

Recombinant rice quiescin sulfhydryl oxidase (rQSOX) has the potential to improve the flour processing quality, but the mechanisms remain unclear. The effects of rQSOX on bread quality, dough rheology, and gluten structure and composition, with glucose oxidase as a positive control, were investigated. rQSOX addition could improve the dough processing quality, as proved by enhanced viscoelastic properties of dough as well as a softer crumb, higher specific volume, and lower moisture loss of bread. These beneficial effects were attributed to gluten protein polymerization and gluten network strengthening, evidenced by the improved concentration of SDS-insoluble gluten and formation of large gluten aggregates and the increased α-helix and β-turn conformation. Furthermore, decreased free sulfhydryl and increased dityrosine in gluten as well as improved H₂O₂ content in dough suggested that the rQSOX dough strengthening mechanism was mainly based on the formation of disulfide bonds and dityrosine cross-links in gluten by both thiol/disulfide direct exchange and hydrogen peroxide indirect oxidation pathways.

Assessing Acerola Powder as Substitute for Ascorbic Acid as a Bread Improver

Bread is one of the most widely consumed products in the world. The use of oxidants is common in bread production, but consumers are demanding products with less additives. Acerola is the fruit with the highest ascorbic acid content and, once dried, it can be used as an oxidant in baking. The use of acerola powder in bread making and its effect on bread quality is studied in this article and compared with the addition of ascorbic acid. For this purpose, flour properties and dough behaviour were analysed with a farinograph and an alveograph. Breads were elaborated with white wheat flour and wholemeal flour; specific volume, loaf height, weight loss, texture, colour, and cell structure were analysed. Acerola powder had similar effects to ascorbic acid: it increased the alveographic strength and the tenacity of the doughs without reducing extensibility; it incremented dough development time (DDT) and dough softening; it increased the specific volume of white wheat breads, and it reduced the hardness of white and wholemeal breads, without significant changes in crust or crumb colour. Therefore, acerola powder can be a natural alternative to the use of ascorbic acid as an improver in bread making.

Simple, Sensitive, and Rapid Voltammetric Detection of Alloxan on Glassy Carbon Electrodes

Alloxan is a chemical generally administered to rats to induce diabetes mellitus, and pharmaceutical industries test the efficacy of their diabetic products on these rats. Alloxan is in a redox cycle with dialuric acid; hence, direct estimation of alloxan may not represent the actual concentration of the same in a given matrix. Also, in recent times, alloxan is added to food materials, especially to the all-purpose flour (maida) to bring softness and white color to the flour. Hence, consumption of food items made from such flour could induce diabetic mellitus in individuals, making it imperative to develop an accurate estimation of alloxan in food items. Herein, a voltammetric-based technique is developed to quantify the alloxan in refined wheat flour (maida) using an unmodified glassy carbon electrode (GCE). The electrochemical method offers rapid sensing while the use of an unmodified GCE surface offers repeatability and reproducibility between measurements. First, alloxan is converted to its stable adduct alloxazine by the reaction with o-phenylenediamine. The alloxazine adduct is electrochemically active, and the concentration of alloxan is estimated as a function of alloxazine formed using the voltammetric technique. The common shortfall in alloxan detection mainly involves its short half-life (∼a minute) whereas the alloxazine adduct formed is stable over a period of time. Using the current approach, alloxan concentration ranging from 10 to 600 μM is detected with a sensitivity of 0.0116 μA/μM. A low limit of detection of 1.95 μM with a precision of 1.2% is achieved using the above method. Real sample analysis revealed the presence of alloxan in all-purpose flour (maida-refined wheat flour) and bread purchased from the local market to the values of 35.76 and 25.03 μM, respectively. The same is confirmed using the gold-standard colorimetric technique.

Vortex- assisted liquid- liquid microextraction for the trace determination of potassium bromate in flour food products

Potassium bromate, also reported as a carcinogenic agent, commonly functions to improve flour in the baking industry to increase bread volume. In this study, a green and novel preconcentration and microextraction method, termed as vortex assisted liquid-liquid microextraction combined with UV-Vis spectrophotometry was developed and utilized for trace determination of Potassium Bromate in food samples. Furthermore, various chemometric methods have been used. Under optimum conditions, the linearity range was obtained in the range between 0.02 and 2 µg/mL. Using the proposed analytical approach, the detection limits and quantitation of KBrO₃ were 0.02 and 0.07 µg/mL, respectively. A pre-concentration factor of 22.2 was reported. The precision of the method was evaluated in the terms of repeatability and reproducibility and expressed by the relative standard deviation; the levels of them were considerably higher than 5.07 and 4.8%. The proposed approach was applied to the determination of trace bromate in different flour products.

Corona Discharge Power of Plasma Treatment Influence on the Physicochemical and Microbial Quality of Enoki Mushroom (Flammulina velutipes)

Plasma treatment was widely known as an effective technology applied for contact-surface decontamination. Enoki (Flammulina velutipes) was an edible-medicinal mushroom with different phytochemicals and bioactive components beneficial for human health. Enoki mushroom had high respiration rate therefore it was highly perishable after harvesting. Moreover, it was greatly susceptible to microbial contamination but it was not feasible to be decontaminated by normal water washing. It’s urgent to extend shelf-life and control microbial criteria on this mushroom in dry manner without aqueous treatment. Corona discharge plasma was among 4 kinds of diverse cold atmospheric pressure plasma sources widely applied in food industry. This study demonstrated the influence of corona discharge plasma power values (control, 120, 150, 180, 210 W) on the physicochemical and microbial characteristics of Enoki mushroom during 10 days of storage at ambient temperature. Results showed that Enoki mushroom should be treated at 150 W of corona discharge plasma power to retain weight loss, total soluble solid, vitamin C in acceptable values while reducing total Aerobic count, Coliform, Enterobacteriaceae as much as possible. At the 10th day of storage, the weight loss, total soluble solid, vitamin C, total Aerobic count, Coliform, Enterobacteriaceae were recorded at 3.35±0.07%, 6.98±0.03 oBrix, 14.81±0.04 mg/100 g, 4.71±0.05 log CFU/g, 3.17±0.02 log CFU/g, 2.13±0.01 CFU/g, respectively. Findings of this research proved that corona discharge plasma pretreatment would be appropriate to maintain physicochemical properties and retard microbial loads on Enoki mushroom during preservation.

Clean Label in Bread

Bread is considered a staple food worldwide, and therefore there is much interest in research around the topic. The bread industry is usually looking for ways to improve its formulations. Therefore, other ingredients such as dough conditioners, crumb softeners, emulsifiers, and surfactants can be added to enhance bread quality. These ingredients perform functions such as helping standardize processes in the industry, reducing dough-mixing time, increasing water absorption, improving bread quality, and extending its shelf life. Consumers are concerned about the effect of these ingredients on their health, and this has increased the popularity of clean-label bread formulations. A clean label generally indicates that a product is free of chemical additives, has an ingredient list that is easy to understand, has undergone natural or limited processing, and/or is organic and free of additives or preservatives. However, there is no scientific definition of the term “clean label.” Researchers have focused on these clean-label initiatives to replace dough strengtheners and preservatives in bread formulations and give consumers what they perceive as a healthier product.

Non-thermal emerging technologies as alternatives to chemical additives to improve the quality of wheat flour for breadmaking: a review

Wheat flour is the main ingredient used in the preparation of bread. Factors such as low gluten content and the addition of nontraditional ingredients in baking affect the quality of wheat flour and may limit its use in baking. With the increasing trend of "clean label" products, it may be interesting to develop and use physical processes to improve the quality of wheat flour and avoid the use of chemical additives. High hydrostatic pressure, non-thermal plasma, ultrasound, ozonation, ultraviolet light, and pulsed light treatments are non-thermal emerging technologies (NTETs) that have been studied for this purpose. They were originally developed to inactivate microorganisms and enzymes in foods. Additionally, these technologies can be used at low temperatures to modify the most important component of wheat flour, i.e., gluten and its fractions, which are responsible for the rheological properties of wheat flour dough. Thus, this review focuses on the effects of these NTETs by considering the following factors: (1) the technological properties of gluten, (2) gluten-starch interactions, (3) possible effects of NTETs on minor components of flours, and (4) the quality of wheat flour and the resulting final products.

History, mechanism of action, and toxicity: a review of commonly used dough rheology improvers

Dough rheology improvers, which often are oxidative reagents in nature, have long been used in bread-making industry to enhance protein crosslinking and subsequently improve the dough rheological properties and bread qualities. Numerous studies were conducted to explore the effects of these oxidative agents on dough quality improving, however, the underlying mechanism of their action during dough development has not been fully understood. Due to the public health concerns, multiple oxidative reagents were banned in some countries across the world, while others are still permitted in accordance with regulations. Therefore, a comprehensive understanding of their application, significance, and safety in bread manufacturing is necessary. This review aims to provide a detailed information about the evolutionary history of several commonly used oxidants acting as dough rheology improvers, their mechanisms of action, as well as their potential toxicity.

Influence of emulsifiers and enzymes on dough rheological properties and quality characteristics of steamed bread enriched with potato pulp

The aim of this study was to evaluate whether processing characteristics of steamed bread enriched with potato pulp could be improved through the addition of different emulsifiers (soy lecithin-Soy L, sodium stearoyl lactate and diacetyl tartaric esters of monoglyceride) and enzymes (glucose oxidase-GOX and transglutaminase). Results showed that separate addition of each emulsifier at 1% concentration or each enzyme at 1.5 U/g could increase the viscoelasticity and strength of potato pulp dough due to enhancement of gluten network. Fermentation properties of dough showed that Soy L and GOX significantly (P < 0.05) increased the maximum dough height and the gas retention capacity during fermentation which promoting dough expansion. Moreover, Soy L and GOX increased specific volume and improved crumb structure and softness of steamed bread, which were consistent with the results of sensory analysis. In conclusion, Soy L and GOX could be used as improvers of potato pulp steamed bread.

A review on mechanistic aspects of individual versus combined uses of enzymes as clean label-friendly dough conditioners in breads

Numerous dough improvers are used alone or in combination to enhance the quality of baked goods such as breads. While modern consumers demand consistent quality, the expectations for ingredients have changed over the past few years, and reformulations have taken place to provide "clean label" options. However, the effects and mechanisms of blended dough conditioners suitable for such baked products have not been systematically summarized. In this review, dough and bread properties as affected by different improver combinations are examined, with a focus on additive or synergistic interactions between enzymes or between enzymes and ascorbic acid. The combination of enzymes that hydrolyze starch and cell wall polysaccharides has been shown to reduce textural hardness in fresh and stored bakes goods such as breads. Enzymes that hydrolyze arabinoxylans, the main nonstarch polysaccharide in wheat, have synergistic effects with enzymes that result in cross-linking of wheat flour biopolymers. In some studies, the effects of bread improvers varied for wheat flours of different strength. Overall, bread products in which wheat is used in whole grain form or in a blend with other flours especially benefit from multiple improvers that target different flour constituents in doughs.

Enzymatic modifications of gluten protein: Oxidative enzymes

Oxidative enzymes treat weak flours in order to restore the gluten network of damaged wheat flour and reduce the economic and technological losses. The present review concentrates on oxidative exogenous enzymes (transglutaminase, laccase, glucose oxidase, hexose oxidase) and oxidative endogenous enzymes (tyrosinase, peroxidase, catalase, sulfhydryl oxidase, lipoxygenase, lipase, protein disulfide isomerase, NAD(P)H-dependent dehydrogenase, thioredoxin reductase and glutathione reductase) and their effects on the rheological, functional, and conformational features of gluten and its subunits. Overall, transglutaminase is used in wheat-based foods through introducing isopeptide bonds (ε-γ glutamyl-lysine). Glucose oxidase, hexose oxidase, peroxidase, sulfhydryl oxidase, lipase, and lipoxygenase form disulfide and nondisulfide bonds through producing hydrogen peroxide. Laccase, tyrosinase, and protein disulfide isomerase form cross-links between tyrosine and cysteine residues by generating radicals. Thioredoxin reductase and glutathione reductase create new inter disulfide bonds. The effect of oxidative enzymes on the formation of covalent cross-linkages were substantially more than non-covalent bonds in gluten structure.

Development of functional foods using psyllium husk and wheat bran fractions: Phytic acid contents

Wheat grain is a rich source of phosphorus which is present mostly as phytic acid and is distributed mainly in the bran and germ fractions. Phytic acid has now been recognized as an important phytochemical having antioxidant properties. This study deals with the determination of total as well as phytic phosphorus contents of psyllium (PS), course (CB) and fine wheat bran (FB) enriched pan bread and Arabic flat bread. The concentration of phytic acid in CB, FB, wheat germ, wholegrain wheat flour (WGF), white wheat flour (WWF), and psyllium were found to be 8.86 mg/g, 8.52 mg/g, 6.05 mg/g, 1.74 mg/g, 0.46 mg/g and 0.02 mg/g, respectively. Most of the phosphorus existed as phytic phosphorus (74.7–90.8%) in FB, CB, germ, and WGF as compared to only 42.6% in WWF. The level of phytic phosphorus in pan bread containing 10% CB, 20% FB (both containing with 5% PS) was found to be 0.63 mg/g and 1.53 mg/g respectively, as compared to only 0.34 mg/g in WWF pan bread, and 0.90 mg/g in WGF pan bread. The phytic phosphorus content in Arabic bread made with WGF and 3% psyllium was 1.32 mg/g as compared to only 0.48 mg/g in WWF Arabic flat bread. The results obtained indicate that the level of phytic phosphorus significantly increased in bread formulations containing CB, FB, and WGF, but no change with psyllium addition was observed. Adding these wheat mill fractions, and psyllium will enable bakeries not only to produce fiber-enriched pan bread and Arabic bread but would also benefit consumers to increase their dietary fiber intakes, and health-promoting phytochemicals coming from wheat bran and germ fractions.

Effects of ascorbic acid and sugar on physical, textural and sensory properties of composite breads

The present study was carried out to demonstrate the combined effects of different maize flour, ascorbic acid and sugar on the physical, textural and sensory properties of composite breads. The composite flour was prepared using 70% of wheat flour and 30% of flour obtained from grain of differently colored maize - light blue, blue, red and yellow maize flour. Chemical characterization of composite flours made with four different types of maize was also assessed. Furthermore, the content of total phenolics, flavonoids, anthocyanins, phenolic acids and antioxidant capacity in composite flours was determined. A total of 12 breads were prepared, four of which were control composite breads, four breads with ascorbic acid, and four were breads with ascorbic acid and sugar. The content of total phenolic compounds showed clear differences among all composite flours. The anthocyanins content determined in composite flours was in the following descending order: blue>red>light blue, while in the yellow maize composite flour anthocyanins were not detected. The results showed that the addition of AsA (0.025%) and sugar (5%) negatively affected the volume as well as the specific volume of composite wheat-maize breads. The texture analysis showed that the addition of AsA in the amount of 0.025% had no impact on springiness, cohesiveness and resilience of bread crumb, while it increased crumb hardness. However, composite breads made with AsA and AsA/sugar showed a more compact structure, with a larger number of cells and smaller mean cell areas. AsA/sugar bread samples within the tested doses had the lowest springiness, which is indicative of brittleness and reflects the tendency of the bread to crumble when slicing. Results of the sensory evaluation revealed that the AsA and sugar addition had a generally positive effect on the investigated sensory attributes.

PDI-Regulated Disulfide Bond Formation in Protein Folding and Biomolecular Assembly

Disulfide bonds play a pivotal role in maintaining the natural structures of proteins to ensure their performance of normal biological functions. Moreover, biological molecular assembly, such as the gluten network, is also largely dependent on the intermolecular crosslinking via disulfide bonds. In eukaryotes, the formation and rearrangement of most intra- and intermolecular disulfide bonds in the endoplasmic reticulum (ER) are mediated by protein disulfide isomerases (PDIs), which consist of multiple thioredoxin-like domains. These domains assist correct folding of proteins, as well as effectively prevent the aggregation of misfolded ones. Protein misfolding often leads to the formation of pathological protein aggregations that cause many diseases. On the other hand, glutenin aggregation and subsequent crosslinking are required for the formation of a rheologically dominating gluten network. Herein, the mechanism of PDI-regulated disulfide bond formation is important for understanding not only protein folding and associated diseases, but also the formation of functional biomolecular assembly. This review systematically illustrated the process of human protein disulfide isomerase (hPDI) mediated disulfide bond formation and complemented this with the current mechanism of wheat protein disulfide isomerase (wPDI) catalyzed formation of gluten networks.

Characterization of recombinant rice quiescin sulfhydryl oxidase and its improvement effect on wheat flour-processing quality

In this study, recombinant rice quiescin sulfhydryl oxidase (rQSOX) was expressed and characterized, and its performance in flour-processing quality was further evaluated. The purified rQSOX exhibited the highest sulfhydryl oxidation activity (1.96 IU/mg) using dithiothreitol as a substrate, accompanying the production of H₂O₂. The optimal temperature and pH were 60 °C and pH 8.0 for rQSOX catalyzing oxidation of dithiothreitol. And rQSOX retained 50% of its maximum activity after incubation at 80 °C for 1 h. Moreover, rQSOX supplementation improved the farinograph properties of dough, indicated by the increased dough stability time and decreased degree of softening, and enhanced viscoelastic properties of the dough. Addition of rQSOX (10 IU/g flour) provided remarkable improvement in specific volume (37%) and springiness (17%) of the steamed bread, and significantly reduced the hardness by half, which was attributed to the strengthened gluten network. The results provide an understanding for rQSOX using in flour-processing industry.

The effect of redox agents on conformation and structure characterization of gluten protein: An extensive review

Gluten protein as one of the plant resources is affected by redox agent. Chemical modifications by redox agent have myriad advantages mainly short reaction times, no requirement for specialized equipment, low cost, and highly clear modification impacts. The gluten network properties could be influenced through redox agents (oxidative and reducing agents) which are able to alter the strength of dough via different mechanisms for various purposes. The present review examined the impact of different redox compounds on gluten and its subunits based on their effects on their bonds and conformations and thus with their impacts on the physico-chemical, morphological, and rheological properties of gluten and their subunits. This allows for the use of gluten for different of purposes in the food and nonfood industry.

A solid sampling approach for direct determination of Cl and S in flour by an elemental analyzer

Direct analysis of flour was proposed for the determination of Cl and S by an elemental analyzer for the first time. The main operational conditions of the direct solid sampling elemental analysis (DSS-EA) were optimized and calibrated by standard solutions, rather than by certified reference material (CRM). Accuracy was evaluated by the analysis of CRM of rice flour and by comparison with analyte determination by independent techniques, i.e., ion chromatography and inductively coupled plasma optical emission spectrometry; both were carried out after microwave-induced combustion. Sample mass from 0.5 to 260 mg was used and limits of quantification of 1.2 µg g^-1 for Cl and 0.2 µg g^-1 for S were achieved. Wheat, whole wheat, potato and corn flour were analyzed by DSS-EA. Concentrations of Cl and S ranged from 4.8 to 685 µg g^-1 and from 13 to 1328 µg g^-1, respectively.

Individual effects of enzymes and vital wheat gluten on whole wheat dough and bread properties

The objective of this research was to determine effects of five enzymes on whole wheat bread properties, particularly loaf volume, bread texture, and staling. Enzymes containing conventional α-amylase (α-amyl), cellulase (cel), glucose oxidase, maltogenic α-amylase (m amyl), and xylanase (xyl) were added at three levels. Vital wheat gluten (VWG) was added as an additional, separate treatment at 2.5% (flour weight basis). Enzymes had minimal effect on water absorption and mixing time. Each enzyme increased specific loaf volume for at least one of the usage levels tested (P < 0.01). Among the enzyme treatments, the greatest loaf volume was seen for xyl at the medium and high levels. No enzyme was as effective as VWG at increasing loaf volume. Overall, enzymes did not significantly change cell structure. The greatest reduction in fresh bread hardness was obtained for the high level of xyl. VWG, m amyl, and xyl reduced the rate of bread firming over 7 days. α-Amyl, cel, and m amyl decreased starch retrogradation at day 7 as measured by differential scanning calorimetry (P < 0.01). M amyl nearly eliminated the endothermic peak for recrystallized amylopectin. This study demonstrated the specific application of enzymes in whole wheat bread to increase loaf volume and decrease initial crumb hardness and bread staling. PRACTICAL APPLICATION: This study will provide guidance for practical uses of enzymes in improving whole wheat dough and bread quality.

Chemical modifications and their effects on gluten protein: An extensive review

Gluten protein as one of the plant resources is susceptible to genetic, physical, chemical, enzymatic and engineering modifications. Chemical modifications have myriad advantages over other treatments, including short reaction times, low cost, no requirement for specialized equipment, and highly clear modification effects. Therefore, chemical modification of gluten can be mainly conducted via acylation, glycosylation, phosphorylation, and deamidation. The present review investigated the impact of different chemical compounds on conformations of gluten and its subunits. Moreover, their effects on the physico-chemical, morphological, and rheological properties of gluten and their subunits were studied. This allows for the use of gluten for a variety of purposes in the food and non-food industry.

Effects of multi-frequency ultrasound on physicochemical properties, structural characteristics of gluten protein and the quality of noodle

In this study, the influence of multi-frequency ultrasound irradiation on the functional properties and structural characteristics of gluten, as well as the textural and cooking characteristics of the noodles were investigated. Results showed that the textural and cooking characteristics of noodles that contain less gluten pretreated by multi-frequency ultrasonic were ultrasonic frequency dependent. Moreover, the noodles that contain a smaller amount of sonicated gluten could achieve the textural and cooking quality of commercial noodles. There was no significant difference in the cooking and texture characteristics between commercial noodles and noodles with 12%, 11%, and 10% gluten pretreated by single-frequency (40 kHz), dual-frequency (28/40 kHz), and triple-frequency sonication (28/40/80 kHz), respectively. Furthermore, the cavitation efficiency of triple-frequency ultrasound was greater than that of dual-frequency and single-frequency. As the number of ultrasonic frequencies increased, the solubility, water holding capacity and oil holding capacity of gluten increased significantly (p < 0.05), and the particle size was reduced from 197.93 ± 5.28 nm to 110.15 ± 2.61 nm. Furthermore, compared to the control group (untreated), the UV absorption and fluorescence intensity of the gluten treated by multi-frequency ultrasonication increased. The surface hydrophobicity of gluten increased from 8159.1 ± 195.87 (untreated) to 11621.5 ± 379.72 (28/40/80 kHz). Raman spectroscopy showed that the α-helix content of all sonicated gluten protein samples decreased after sonication, while the β-sheet and β-turn content increased, and tryptophan and tyrosine residues were exposed. Through scanning electron microscope (SEM) analysis, the gluten protein network structure after ultrasonic treatment was loose, and the pore size of the gluten protein network increased from about 10 μm (untreated) to about 26 μm (28/40/80 kHz). This work elucidated the effect of ultrasonic frequency on the performance of gluten, indicating that with increasing frequency combination increases, the ultrasound effect became more pronounced and protein unfolding increased, thereby impacting the functional properties and the quality of the final product. This study provided a theoretical basis for the application of multi-frequency ultrasound technology in the modification of gluten protein and noodle processing.

The wPDI Redox Cycle Coupled Conformational Change of the Repetitive Domain of the HMW-GS 1Dx5-A Computational Study

The repetitive sequence of glutenin plays an important role in dough rheology; however, its interaction with wheat protein disulfide isomerase (wPDI) remains unclear. In this study, the conformations of wild type glutenin repetitive sequence (WRS) from the high molecular weight glutenin subunit (HMW-GS) 1Dx5, an artificially designed glutenin repetitive sequence (DRS) of which the amino acid composition is the same but the primary structure is different, and wPDI under different redox states were simulated. The molecular interactions between the aforementioned repetitive sequences with wPDI under different redox states were further investigated. The results indicated that the repetitive sequences bind to the b and b' domains of an "open", oxidized wPDI (wPDI^O) which serves as the acceptor state of substrate. The repetitive sequence is partially folded (compressed) in wPDI^O, and is further folded in the thermodynamically favored, subsequent conformational transition of wPDI^O to reduced wPDI (wPDI^R). Compared with the artificially designed one, the naturally designed repetitive sequence is better recognized and more intensively folded by wPDI for its later unfold as the molecular basis of dough extension.

Effects of edible plant polyphenols on gluten protein functionality and potential applications of polyphenol-gluten interactions

Expanding plant-based protein applications is increasingly popular. Polyphenol interactions with wheat gluten proteins can be exploited to create novel functional foods and food ingredients. Polyphenols are antioxidants, thus generally decrease gluten strength by reducing disulfide cross-linking. Monomeric polyphenols can be used to reduce dough mix time and improve flexibility of the gluten network, including to plasticize gluten films. However, high-molecular-weight polyphenols (tannins) cross-link gluten proteins, thereby increasing protein network density and strength. Tannin-gluten interactions can greatly increase gluten tensile strength in dough matrices, as well as batter viscosity and stability. This could be leveraged to reduce detrimental effects of healthful inclusions, like bran and fiber, to loaf breads and other wheat-based products. Further, the dual functions of tannins as an antioxidant and gluten cross-linker could help restructure gluten proteins and improve the texture of plant-based meat alternatives. Tannin-gluten interactions may also be used to reduce inflammatory effects of gluten experienced by those with gluten allergies and celiac disease. Other potential applications of tannin-gluten interactions include formation of food matrices to reduce starch digestibility; creation of novel biomaterials for edible films or medical second skin type bandages; or targeted distribution of micronutrients in the digestive tract. This review focuses on the effects of polyphenols on wheat gluten functionality and discusses emerging opportunities to employ polyphenol-gluten interactions.

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.