Gluten Functionality Research Articles

Unravelling the bread-making functionality of gluten-rich sub-aleurone flour obtained by dry fractionation of wheat miller’s bran

The residual endosperm of wheat miller’s bran is rich in gluten proteins due to the presence of protein-rich sub-aleurone cells. Here, the goal was to gain insight into the bread-making functionality of sub-aleurone gluten-enriched fractions obtained through dry fractionation of miller’s bran and the inherent bread-making functionality of sub-aleurone gluten. Therefore, two sub-aleurone gluten-enriched fractions (Sub-alF and Sub-alC), differing in particle size distribution and chemical composition, were prepared from miller’s bran using impact milling, sieving, and air classification. Substituting 22.5% of white flour with Sub-alF, Sub-alC, commercial gluten A (GluA) and B (GluB), all standardised to a protein content of 20.6 % with wheat starch, led to an increase in specific loaf volume of 14.8%, 14.0%, 14.3%, and 21.8%, respectively. Despite their higher level of bran contamination and lower relative gluten content, Sub-alF and Sub-alC were equally functional as commercial gluten (GluA). This could be due to wet fractionation, which is used in commercial gluten production, reducing the functionality of gluten, as indicated by comparing the functionality of gluten in Sub-alC and gluten isolated via wet fractionation from Sub-alC with GluA. Substituting 6% of white flour with gluten isolated via wet fractionation from Sub-alC and from the corresponding flour increased the specific volume by 27.2% and 29.4%, respectively. Sub-aleurone gluten and flour gluten were, hence, functionally comparable. In conclusion, the sub-aleurone’s high content of functional gluten enables the production of functional gluten-enriched ingredients from miller’s bran.

Effect of high-molecular-weight glutenin subunit deletion on gluten functionality and Chinese southern-type steamed bread quality

High-molecular-weight glutenin subunit (HMW-GS) is key factor in gluten strength and end-use quality. However, the contribution of individual HMW-GS on dough strength and Chinese southern-type steamed bread (CSTSB) quality remained unknown. In this study, we investigated the effects of individual HMW-GS deletion on CSTSB quality. The HMW-GS deletion led to significant reductions in glutenin/gliadin ratios, disulfide bond content, and SDS-unextractable polymeric protein formation. Additionally, HMW-GS deletion resulted in decreased gluten protein chain length, molecular weight, and particle size, contributing to increased thermal instability and reduced crosslinking. The HMW-GS deletion weakened dough strength but improved CSTSB performance, particularly in Dx2d and Dy12d. In-silico analysis further revealed strong interactions between Bx7 and Dx2, primarily driven by desolvation energy, highlighting their crucial role in stabilizing gluten protein interactions.

Protein-polyphenol conjugation through alkali treatment improves the structure and functionality of gluten

Protein-polyphenol conjugation through alkali treatment improves the structure and functionality of gluten

Influence of salts on the protein composition and functionality of gluten

Different salts were added to gluten to investigate the effects of different cations on a fully developed gluten network. The chloride salts KCl, NaCl, MgCl2, CaCl2 were mixed with pre-isolated wet gluten in a low and high dose, and the gluten was dried at 40 °C and 80 °C to yield vital gluten. The impact of the individual cations on the gluten protein composition and functionality was determined by analysis of chemical and rheological properties of vital and wet gluten. All cations influenced the gluten protein composition and the rheological behaviour. While the observed changes could not be attributed to the order of the Hofmeister series, monovalent, kosmotropic cations K+ and Na+ and divalent, chaotropic cations Mg2+ and Ca2+ showed similar behaviour in terms of protein composition and functional properties. Salts therefore have an influence on the gluten protein composition of a fully developed gluten network and gluten protein composition and functionality can be altered by an after-treatment process in a targeted way.

Rice-Based Gluten-Free Foods and Technologies: A Review.

Rice, one of the most widely consumed staples worldwide, serves as a versatile gluten-free substitute. However, review articles on technological developments in grain-free production focusing on rice are scarce. This review assesses various research results concerning the quality attributes of rice-based gluten-free foods, including bread, pasta, and beer. To optimize the key attributes in processed products, such as dough leavening in bread and the physical and cooking properties of noodles and pasta, research has focused on blending different gluten-free grains and incorporating additives that mimic the gluten function. Additionally, various processing technologies, such as starch preprocessing and extrusion puffing processes, have been employed to boost the quality of rice-based gluten-free products. Today, a variety of products, including bread, noodles, and beer, use rice as a partial replacement for barley or wheat. With rapid advancements in technology, a noticeable portion of consumers now shows a preference for products containing rice as a substitute. This trend indicates that rice-based gluten-free foods can be enhanced by leveraging the latest developments in gluten-free product technologies, particularly in countries where rice is a staple or is predominantly cultivated.

Partial C-terminal truncation of Bx and Dy high molecular weight glutenin subunits after conserved aspartate

The composition of polymeric gluten proteins and interaction with non-covalently associated gliadins define the functional utility of a flour. This composition is dictated by the timing of cellular and genetic events in the plant and the developing seed. This interplay and its effect on gluten functionality is poorly understood and could provide a new opportunity for improving wheat quality in the future. Truncated proteoforms of high-molecular weight glutenin subunits (HMWGS) were observed for Bx and Dy subtypes across 49 Canadian bread wheat and 16 durum varieties. The relative abundances of these variants ranged from 7.5% to 37.7% and abundances of Bx and Dy variants were highly correlated (r2 = 0.85). HMWGS Bx7* and Dy10 were purified and the mass difference was shown to be from the loss of a C-terminal hexapeptide after a conserved aspartate residue. This aspartate was present at the ω-7 position in >90% of HMWGS accessions and the C-terminal sequence was highly conserved. Importantly, all HMWGS subtypes contain the same conserved sequences, but truncated variants were never observed for By, Dx and Ax HMWGS. The potential impact of these truncated HMWGS on gluten form and function is discussed.

Inactivation of Salmonella and Shiga-toxin producing Escherichia coli on soft wheat kernels using vacuum steam pasteurization

Wheat, the raw material for flour milling, can be contaminated with enteric pathogens, leading to outbreaks linked to flour. In previous lab-scale studies, vacuum steam treatment was able to reduce Salmonella Enteritidis PT30 and Shiga-toxin producing E. coli (STEC) O121 levels on soft wheat kernels while maintaining flour quality and gluten functionality. This study used a newly designed lab-scale vacuum steam pasteurizer (VSP) to evaluate its efficacy to inactivate multiple strains of Salmonella and STEC on soft wheat by modeling the non-isothermal time-temperature history during treatment and reduction of the microbial populations. The results demonstrated that vacuum steam treatment could effectively disinfect wheat grains inoculated with enteric pathogens. In this study, Salmonella strains were less thermally resistant than STEC strains. The D75°C of Salmonella strains were 2.8 and 3.2 min, and the D75°C of STEC ranged from 3.1 to 4.6 min. E. faecium had a D75°C of 3.3 min, which indicates that it could be used as surrogate for larger scale evaluation of vacuum steam pasteurization in the future but was not conservative compared to some of the STEC strains.

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.

Strain-dependent assessment of dough's polymer structure and functionality during the baking process.

During the baking process, the functionality of the heterogeneous dough matrix changes as the composing polymers experience conformational transition processes. The thermally induced structural changes affect the involvement and functionality of the polymers in the dough matrix. With the main hypothesis being that different types and magnitudes of strain exerted during the measurement would provide information on different structural levels and interactions, SAOS rheology in multiwave mode and large deformation extensional rheometry were applied to two microstructurally different systems. The functionality of the two systems, a highly connected standard wheat dough (φ ≈ 1.1) and an aerated, yeasted wheat dough (φ ≈ 2.3), depicting limited connectivity and strength of interactions, was accessed under different deformations and types of strains. Applying SAOS rheology, starch functionality prevailed on the behavior of the dough matrix. In contrast, gluten functionality prevailed the large deformation behavior. Using an inline fermentation and baking LSF technique, the heat-induced gluten polymerization was shown to increase strain hardening behavior above 70°C. In the aerated system, the strain hardening effect became already evident under small deformation testing, as the expansion of gas cells caused a pre-expansion of the gluten strands. The expanded dough matrix of yeasted dough was further shown to be substantially subjected to degradation once the network reached beyond its maximal gas holding capacity. Using this approach, the combined impact of yeast fermentation and thermal treatment on the strain hardening behavior of wheat dough was revealed for the first time by LSF. Furthermore, the rheological properties were successfully linked to oven rise behavior: a decreasing connectivity combined with the initiation of strain hardening by fast extension processes occurring in the yeasted dough matrix during the final baking phase was linked to limited oven rise functionality prematurely around 60°C.

Missense alleles of the HMW glutenin subunits Dx5 and Dy10 have small changes in function relative to missense changes in Puroindoline a and b

AbstractBackground and ObjectivesThe high molecular weight glutenin subunit genes (HMW‐GS) in wheat (Triticum aestivum L.) play a key role in determining dough functionality. More specifically allelic variation for the Glu‐D1 subunit loci is consistently associated with bread making quality. Since much of the hard wheat germplasm is fixed for the more favorable 1Dx5 + 1Dy10 haplotype, our goal was to identify allelic variation in 1Dx5 and 1Dy10 HMW‐GS genes using an ethyl methanesulfonate (EMS) mutagenized population in the soft white spring wheat cultivar “Alpowa.” The same source population was previously used in screening for creating novel alleles in Puroindoline a (Pina) and Puroindoline b (Pinb) which are responsible for grain hardness variation. Direct sequencing of 384 M3 families identified 135 point mutations equally dispersed across 1Dx5 and 1Dy10. The mutation discovery rate was 1/12.7 kb of DNA, equal to that found in the Pin loci. Mutation carrying plants were crossed to the nonmutagenized Alpowa parent to create F2 populations segregating for the induced EMS HMW Glutenin mutations. Swelling index of gluten (SIG) was measured from seed from field grown plants to assess the impact of each EMS mutation upon Glutenin function.FindingsNonsense mutations in both 1Dx5 and 1Dy10 reduced SIG values, indicating both 1Dx5 and 1Dy10 are needed for gluten functionality. Missense mutations did not alter SIG values compared to their wild type counterparts. In contrast missense mutations within the tryptophan‐rich region of both PINS increased grain hardness pointing to the importance of this protein region. No such region in 1Dx5 or 1Dy10 was found indicating these proteins are structurally stable and tolerant of amino acid substitution.ConclusionsResults from the Glu‐D1 subunit and Pin loci show that useful phenotypic variation can be created using EMS mutagenesis for genes where naturally occurring mutations occur from amino substitutions as is the case for the Pin loci.Significance and NoveltyEMS induced mutations are useful for creating new alleles in storage proteins with much greater impacts in genes that have a defined active site as for the Pin loci than in genes such as the HMW Glu‐1 genes which have a long repetitive region.

Impact of Chlorinated Water on Pathogen Inactivation during Wheat Tempering and Resulting Flour Quality

Outbreaks of enteric pathogens linked to wheat flour have led the wheat milling industry to seek solutions addressing this food safety concern. Chlorinated water at 400 to 700 ppm has been used in the flour milling industry as a tempering aid to control growth of yeast and mold in tempering bins. However, the effectiveness of chlorinated water for inactivating enteric pathogens on wheat kernels was unknown. Five strains of Shiga toxin-producing Escherichia coli and two strains of Salmonella were inoculated onto hard red spring wheat at 7 log CFU/g and stored at room temperature for 1 month. Inoculated wheat was tempered with four concentrations (0, 400, 800, and 1,200 ppm) of chlorinated water (pH 6.5). The reduction due to chlorine was determined by calculating change in microbial loads at each chlorine level by using the response at 0 ppm as a reference. Uninoculated wheat tempered with chlorinated water was used to measure flour quality parameters. Changes in pathogen population over 18 h ranged from -2.35 to -0.30 log CFU/g with 800 ppm of chlorinated water and were not significantly different from changes at 400 and 1,200 ppm. Significant (P < 0.05) differences in the extent of reduction were observed among strains. However, the effect of chlorinated water at reducing native microbes on wheat kernels was minimal, with an average reduction of 0.39 log CFU/g for all concentrations. No significant (P > 0.05) changes occurred in flour quality and gluten functionality or during bread making for grains tempered at 400 and 800 ppm of chlorinated water. There were small but significant (P < 0.05) changes in flour protein content, final viscosity, and water absorption when tempered with 1,200 ppm of chlorinated water. The data showed that the level of chlorinated water currently used in industry for tempering could reduce enteric pathogen numbers by 1.22 log CFU/g for Shiga toxin-producing Escherichia coli and 2.29 log CFU/g for Salmonella, with no significant effects on flour quality and gluten functionality.

Relation between polymer transitions and the extensional viscosity of dough systems during thermal stabilization assessed by lubricated squeezing flow

Polymer transitions occurring during the thermal processing of dough are defining the rheological behaviour of solidifying dough. Yeast, an essential ingredient in breadmaking, plays an important role in this transformation process, but its impact on the transitional behavior of the polymers remains unknown. Therefore, the aim of this study was to elucidate the impact of hydrothermally induced polymer transitions on the elongational rheological behavior of dough under process-relevant strain-strain-rate combinations transitions in dependence of the presence of yeast. Using elongational rheology together with DSC, TD-NMR and microscopy, yeast-induced degradation on the microstructural level (average decrease of protein strand length of 46%) and microstructural level were shown to affect the course of the starch gelatinization process and the functionality of gluten while baking. These findings can be used to relate oven rise performance to fundamental rheological behavior based on occurring phase transitions, leading to a more comprehensive process understanding.

Impact of oleuropein on rheology and breadmaking performance of wheat doughs, and functional features of bread

SummaryOleuropein (OP) is a polyphenol present in drupes and leaves of olive tree with health benefits and, as antioxidant, potentiality to alter gluten functionality. Effects of OP inclusion to wheat flour (0.01% and 0.02% on flour weight basis) on dough rheology and breadmaking performance, and bread features were investigated. Farinograph, uniaxial extension and shear rheometry (oscillatory and creep‐recovery) were applied. Doughs containing OP were stronger, more elastic, and less sticky indicating the ability of OP to act as flour improver. The strengthening effect of OP on gluten led to the increase in bread volume and softer crumb compared to control. A lower crumb density of bread with the addition of OP was related to a higher in vitro glycaemic response. An increase in the antioxidant capacity of bread made with the phenolic compound was also found.

The effect of infrared radiation on gluten aggregation and pasting properties of wheat flours with different protein content

The aim of this study was to investigate the potential of a designed infrared (IR) assisted ribbon mixer system for thermal modification of wheat flours that had different protein content and intended use (bread, cake, and biscuit wheat flours). Additionally, the effect of IR treatment, which was conducted using five different IR power levels for either short or medium wave IR emitters, on gluten content and quality, gluten aggregation and rheological properties of flours were determined. IR treatment resulted in minor crude protein loss (1–2%) in flours. Moreover, the effect of IR treatment on wet gluten and gluten index values was insignificant for bread and cake wheat flours, while it was significant for biscuit wheat flour. Torque maximum values were not significantly affected from IR treatment regardless of the flour type while the treatment caused a significant decrease in peak maximum time values up to 33%. Besides, the effect of IR treatment on maximum viscosity and breakdown viscosity values was insignificant for all flour types (p > 0.05). It was concluded that IR treatment may cause minor changes in gluten functionality and pasting properties of the flours depending on the type of flour and process conditions.

Solvent retention capacity: Supplemental solvents for evaluation of gluten quality

Solvent retention capacity (SRC) is a solvation test for wheat flour in which functional contributions of different polymeric components are predicted based on their swelling behavior with different diagnostic solvents. To assess the functionality of individual gluten components, four solvents have been proposed: 1) 55% aqueous ethanol for gliadins; 2) 0.75% sodium dodecyl sulfate (SDS) for glutenin macropolymer; 3) 0.006% sodium metabisulfite (MBS) for gluten strength; and 4) 0.75% SDS + 0.006% MBS for glutenin macropolymer without disulfide network. This research aimed to study the gluten functionality of commercial wheat flour samples by the four proposed supplemental diagnostic solvents. Commercial wheat samples were purchased in 2020 at a grocery store in Fargo, North Dakota. Four different brands from three flour types (bread flour, all-purpose flour, and cake flour) were analyzed. These flour types represent wheat flour from three different U.S. wheat classes, hard spring wheat, hard winter wheat, and soft wheat. SRC was measured according to the AACC-approved method 56–11.02 with modifications. The supplementary solvents 55% aqueous ethanol, 0.75% SDS, 0.006% MBS, and 0.75% SDS +0.006% MBS were used instead of the traditional SRC solvents. Highly significant (p ≤ 0.001) and positive correlations between SDS SRC, MBS SRC, and SDS + MBS SRC solvents and the analyzed rheological and baking quality traits, especially water absorption and loaf volume. Additionally, when protein composition was assessed, the three previously mentioned supplementary SRC solvents denoted a significant (p ≤ 0.01) and positive correlation with the glutenin polymers fraction, which is associated with dough functionality. These results highlight the importance of assessing specific flour polymers' functional contributions to predict each flour type's end-use potential.

Water Absorption Capacity Determines the Functionality of Vital Gluten Related to Specific Bread Volume.

Vital gluten is often used in baking to supplement weak wheat flours and improve their baking quality. Even with the same recipe, variable final bread volumes are common, because the functionality differs between vital gluten samples also from the same manufacturer. To understand why, the protein composition of ten vital gluten samples was investigated as well as their performance in a microbaking test depending on the water content in the dough. The gluten content and composition as well the content of free thiols and disulfide bonds of the samples were similar and not related to the specific bread volumes obtained using two dough systems, one based on a baking mixture and one based on a weak wheat flour. Variations of water addition showed that an optimal specific volume of 1.74–2.38 mL/g (baking mixture) and 4.25–5.49 mL/g (weak wheat flour) was reached for each vital gluten sample depending on its specific water absorption capacity.

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.

Reinventing the nutraceutical value of gluten: The case of l-theanine-gluten as a potential alternative to the gluten exclusion diet in celiac disease

Functional foods have created an open environment for the development of new solutions to health-related issues. In celiac disease, there is still no therapeutic alternative other than the observance of a gluten-free diet. In this context, we developed a wheat flour enriched in l-theanine aimed to be a potential alternative to the gluten-free diet. Through microbial transglutaminase-catalysed transamidation of gluten proteins using ethylamine as amine nucleophile, substantial amounts of glutamine residues were converted in theanine residues. Furthermore, using T-cell lines generated from intestinal biopsy specimens of celiac disease patients, this treatment showed the potential to strongly reduce the ability of gluten proteins to stimulate a T-cell-mediated immune response. From a rheological point of view, the functionality of gluten was retained. Considering L-theanine’s evidence-based health benefits, a novel functional food is presented here and for celiac disease can be a path towards the development of an alternative to the gluten-free diet.

Sprouting improves the bread-making performance of whole wheat flour (Triticum aestivum L.).

Pre-harvest sprouting of wheat is viewed negatively because of the high level of enzymatic activity, which leads to a deterioration in the bread-making performance of the related flours. On the other hand, improvements in bread properties (i.e. volume and crumb softness) are reported when sprouted wheat under controlled conditions is used in mixtures with a conventional unsprouted flour. However, knowledge about the effects of sprouting on gluten functionality and its relationship with bread features is still limited, especially in the case of whole wheat flour. Under the conditions applied in this study (48 h, 20 °C and 90% relative humidity), proteins of sprouted wheat were still able to aggregate, even if changes in gluten aggregation kinetics suggested gluten weakening. On the other hand, sprouting led to an increase in gluten stretching ability, suggesting an increase in dough extensibility. In the dough system, sprouting was responsible for a decrease in water absorption, development time, and stability during mixing. However, when the values for development time and water absorption indicated by the Farinograph® were followed carefully, sprouting improved bread height (~20%), specific volume (~15%), and crumb softness (~200% after 24 h of storage), even when whole wheat flour was used. It is possible to produce bread with improved volume and crumb softness using whole wheat flour from sprouted kernels. Thus, sprouting can be exploited as a pre-treatment to improve the bread-making performance of fiber-enriched systems. © 2020 Society of Chemical Industry.

High Molecular Weight Glutenin Subunits 1Bx7 and 1By9 Encoded by Glu-B1 Locus Affect Wheat Dough Properties and Sponge Cake Quality.

High molecular weight glutenin subunits (HMW-GSs) are important components of wheat (Triticum aestivum L.) gluten proteins that affect the processing quality of wheat dough. However, the contributions of individual HMW-GS to sponge cake quality still remain unclear. To investigate the effects of 1Bx7 and 1By9 at Glu-B1 on wheat gluten properties and sponge cake quality, we screened an ethylmethanesulfonate (EMS)-mutagenized wheat population and obtained two independent mutants that lack 1Bx7 and another two mutants that lack 1By9. The absence of 1Bx7 or 1By9 significantly affects the accumulation levels of gluten proteins and the formation of a gluten network. Quality testing indicated that the lack of 1Bx7 or 1By9 leads to weaker dough strength and inferior sponge cake performance. These results demonstrate that 1Bx7 and 1By9 make important contributions to gluten functionality and sponge cake quality.