Control of the oil content of fried dough sticks through modulating structure change by reconstituted gluten fractions.

In our study, we explored how gluten's role during dough formation and thermal processing can mitigate the adverse effects of physical factors on product quality. We discovered that a gluten network with a gliadin/glutenin ratio of 5:5 effectively limits oil penetration into the dough's core. This particular ratio is found to reduce the exposure of hydrophobic groups due to the presence of hydrated ß-sheet structures. In contrast, gluten networks with higher gliadin proportions than typical wheat gluten tend to be looser, leading to increased chromophore exposure and facilitating more oil absorption. These observations highlighted the complex link between changes in gluten structure, varying protein compositions, and oil content in fried dough sticks. This research provided a foundation for developing specialized low-fat wheat flour and improving the quality of fried dough products.

Wheat gluten structure and (non-)covalent network formation during deep-fat frying.

The aim of this work was to investigate wheat gluten protein network structure throughout the deep-frying process and evaluate its contribution to frying-induced micro- and macrostructure development. Gluten polymerization, gluten-water interactions, and molecular mobility were assessed as a function of the deep-frying time (0 - 180 s) for gluten-water model systems of differing hydration levels (40 - 60 % moisture content). Results showed that gluten protein extractability decreased considerably upon deep frying (5 s) mainly due to glutenin polymerization by disulfide covalent cross-linking. Stronger gliadin and glutenin protein-protein interactions were attributed to the formation of covalent linkages and evaporation of water interacting with protein chains. Longer deep-frying (> 60 s) resulted in progressively lower protein extractabilities, mainly due to the loss in gliadin protein extractability, which was associated with gliadin co-polymerization with glutenin by thiol-disulfide exchange reactions. The mobility of gluten polymers was substantially reduced during deep-frying (based on the lower T2 relaxation time of the proton fraction representing the non-exchanging protons of gluten) and gluten proteins gradually transitioned from the rubbery to the glassy state (based on the increased area of said protons). The sample volume during deep-frying was strongly correlated to the reduced protein extractability (r = -0.792, p < 0.001) and T2 relaxation time of non-exchanging protons of gluten proteins (r = -0.866, p < 0.001) thus demonstrating that the extent of gluten structural expansion as a result of deep-frying is dictated both by the polymerization of proteins and the reduction in their molecular mobility.

Amyloid-like Aggregation of Wheat Gluten and Its Components during Cooking: Mechanisms and Structural Characterization.

Amyloid-like aggregation widely occurs during the processing and production of natural proteins, with evidence indicating its presence following the thermal processing of wheat gluten. However, significant gaps remain in understanding the underlying fibrillation mechanisms and structural polymorphisms. In this study, the amyloid-like aggregation behavior of wheat gluten and its components (glutenin and gliadin) during cooking was systematically analyzed through physicochemical assessment and structural characterization. The presence of amyloid-like fibrils (AFs) was confirmed using X-ray diffraction and Congo red staining, while Thioflavin T fluorescence revealed different patterns and rates of AFs growth among wheat gluten, glutenin, and gliadin. AFs in gliadin exhibited linear growth curves, while those in gluten and glutenin showed S-shaped curves, with the shortest lag phase and fastest growth rate (t1/2 = 2.11 min) observed in glutenin. Molecular weight analyses revealed AFs primarily in the 10-15 kDa range, shifting to higher weights over time. Glutenin-derived AFs had the smallest ζ-potential value (-19.5 mV) and the most significant size increase post cooking (approximately 400 nm). AFs in gluten involve interchain reorganization, hydrophobic interactions, and conformational transitions, leading to additional cross ß-sheets. Atomic force microscopy depicted varying fibril structures during cooking, notably longer, taller, and stiffer AFs from glutenin.

Wheat-Based Glues in Conservation and Cultural Heritage: (Dis)solving the Proteome of Flour and Starch Pastes and Their Adhering Properties.

Plant-based adhesives, such as those made from wheat, have been prominently used for books and paper-based objects and are also used as conservation adhesives. Starch paste originates from starch granules, whereas flour paste encompasses the entire wheat endosperm proteome, offering strong adhesive properties due to gluten proteins. From a conservation perspective, understanding the precise nature of the adhesive is vital as the longevity, resilience, and reaction to environmental changes can differ substantially between starch- and flour-based pastes. We devised a proteomics method to discern the protein content of these pastes. Protocols involved extracting soluble proteins using 0.5 M NaCl and 30 mM Tris-HCl solutions and then targeting insoluble proteins, such as gliadins and glutenins, with a buffer containing 7 M urea, 2 M thiourea, 4% CHAPS, 40 mM Tris, and 75 mM DTT. Flour paste's proteome is diverse (1942 proteins across 759 groups), contrasting with starch paste's predominant starch-associated protein makeup (218 proteins in 58 groups). Transformation into pastes reduces proteomes' complexity. Testing on historical bookbindings confirmed the use of flour-based glue, which is rich in gluten and serpins. High levels of deamidation were detected, particularly for glutamine residues, which can impact the solubility and stability of the glue over time. The mass spectrometry proteomics data have been deposited to the ProteomeXchange, Consortium (http://proteomecentral.proteomexchange.org) via the MassIVE partner repository with the data set identifier MSV000093372 (ftp://MSV000093372@massive.ucsd.edu).

Fabrication and characterization of novel prolamin nanoparticle-filled starch gels incorporating resveratrol.

This study aimed to improve the mechanical properties of wheat starch gels (WSG) and the stability and bioaccessibility of resveratrol (Res) in prolamin nanoparticles. Res-loaded gliadin (Gli), zein, deamidated gliadin (DG) and deamidated zein (DZ) nanoparticles were filled in WSG. The hardness, G' and G'' of WSG were notably increased. It can be attributed to the more ordered and stable structure induced by the interaction of prolamin nanoparticles and starch. The Res retention of nanoparticles and nanoparticle-filled starch gels was at least 24.6 % and 36.0 % higher than free Res upon heating. When exposed to ultraviolet, the Res retention was enhanced by over 6.1 % and 37.5 %. The in-vitro digestion demonstrated that the Res releasing percentage for nanoparticle-filled starch gels was 25.8 %-38.7 % lower than nanoparticles in the simulated stomach, and more Res was released in the simulated intestine. This resulted in a higher bioaccessibility of 82.1 %-93.2 %. The bioaccessibility of Res in Gli/Res/WSG and DG/Res/WSG was greater than that of Zein/Res/WSG and DZ/Res/WSG. More hydrophobic interactions occurred between Res and Gli, DG. The interactions between Res and zein, DZ were mainly hydrogen bonding. The microstructure showed that nanoparticles exhibited dense spherical structures and were uniformly embedded in the pores of starch gels.

Influence of pH and lipid membrane on the liquid-liquid phase separation of wheat γ-gliadin in aqueous conditions.

Protein body (PB) formation in wheat seeds is a critical process influencing seed content and nutritional quality. In this study, we investigate the potential mechanisms governing PB formation through an in vitro approach, focusing on γ-gliadin, a key wheat storage protein. We used a microfluidic technique to encapsulate γ-gliadin within giant unilamellar vesicles (GUVs) and tune the physicochemical conditions in a controlled and rapid way. We examined the influence of pH and protein concentration on LLPS and protein-membrane interactions using various microscopy and spectroscopy techniques. We showed that γ-gliadin encapsulated in GUVs can undergo a pH-triggered liquid-liquid phase separation (LLPS) by two distinct mechanisms depending on the γ-gliadin concentration. At low protein concentrations, γ-gliadins phase separate by a nucleation and growth-like process, while, at higher protein concentration and pH above 6.0, γ-gliadin formed a bi-continuous phase suggesting a spinodal decomposition-like mechanism. Fluorescence and microscopy data suggested that γ-gliadin dense phase exhibited affinity for the GUV membrane, forming a layer at the interface and affecting the reversibility of the phase separation.

Rapid analysis of wheat gluten composition using a triple ELISA.

BACKGROUND: Gluten composition is an important quality parameter of wheat flour. Reversed-phase high-performance liquid chromatography (RP-HPLC) is a state-of-the-art method for its analysis. As this is a very labour-intensive and time-consuming procedure, alternative faster methods are desirable. Enzyme-linked immunosorbent assay (ELISA) is a high-throughput method often used for the analysis of gluten traces in gluten-free products. In this proof-of-principle study, we introduce an experimental triple ELISA for the relative quantitation of gliadins, high-molecular-weight glutenin subunits (HMW-GS) and low-molecular-weight glutenin subunits (LMW-GS) of one wheat flour extract. RESULTS: The results of 80 common wheat flour samples obtained from the triple ELISA and RP-HPLC were correlated. The results for gliadins (r = 0.69) and HMW-GS (r = 0.81) showed a medium and high correlation, respectively. Only a very weak correlation of ELISA and RP-HPLC results was observed for LMW-GS (r = 0.49). Results for glutenins (r = 0.69) and gluten (r = 0.72) had a medium correlation. The gliadin/glutenin ratio (r = 0.47) and LMW-GS/HMW-GS ratio (r = 0.40) showed a weak or no correlation. The gliadin, LMW-GS and gluten contents were lower and the HMW-GS content was higher in the ELISA measurement compared to RP-HPLC. CONCLUSION: The quantitation of gliadins and HMW-GS by the experimental triple ELISA showed comparable results to RP-HPLC, whereas no strong correlation between the results from the two methods was found for LMW-GS. Overall, the experimental triple ELISA is suitable for relative gluten quantitation, especially for the analysis of large sample sets. Further work will focus on improving the experimental procedure of the ELISA. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

High-throughput quantitative assessments of the chemical complementarity of celiac disease-related IGH CDR3s and a gliadin epitope.

The long-term value of efficient antigen discovery includes gaining insights into the variety of potential cancer neoantigens, effective vaccines lacking adverse effects, and adaptive immune receptor (IR) targets for blocking adaptive IR-antigen interactions in autoimmunity. While the preceding goals have been partially addressed via big data approaches to HLA (human leukocyte antigen)-epitope binding, there has been little such progress in the big data setting for adaptive IR-epitope binding. This delay in progress for the latter is likely due to, among other things, the much more complicated adaptive IR repertoire in an individual compared to individual HLA alleles. Thus, results described here represent the application of an algorithm for efficient assessment of immunoglobulin heavy chain complementarity determining region-3 (IGH CDR3)-gliadin epitope interactions, with a focus on epitopes known to be associated with an immune response in celiac disease. The hydrophobic, chemical complementarity between celiac case IGH CDR3s and known celiac epitopes was found to be greater in comparison to the hydrophobic, chemical complementarity between the same celiac case IGH CDR3s and a series of control epitopes. Thus, the approaches indicated here likely offer guidance for the development of conveniently applied algorithms for antigen verification and discovery.

Effects of Four Highland Barley Proteins on the Pasting Properties and Short-Term Retrogradation of Highland Barley Starch.

This study evaluated the effects of four highland barley proteins (HBPs), namely, albumin, globulin, gliadin and glutenin, on the short-term retrogradation of highland barley starch (HBS). The findings reveal that HBPs could reduce the viscosity, storage modulus and hardness of HBS, with albumin and globulin showing more prominent effects. Furthermore, with the addition of HBPs, the loss tangent (tan δ) of HBS loss increased from 0.07 to 0.10, and the enthalpy of gelatinization decreased from 8.33 to 7.23. The degree of retrogradation (DR%) of HBS was 5.57%, and the DR% decreased by 26.65%, 38.78%, 11.67% and 20.29% with the addition of albumin, globulin, gliadin and glutenin, respectively. Moreover, the relative crystallinity (RC) and the double helix structures were inhibited with the HBPs' incorporation. Meanwhile, the HBPs also could inhibit water migration and improve the structure of HBS gels. In summary, HBPs could inhibit the retrogradation behavior of HBS, which provides new theoretical insights for the production studies of highland barley foods.

Ultrasound-enhanced covalent reaction of gliadin: the inhibition of antigenicity and its potential mechanisms.

BACKGROUND: Wheat proteins can be divided into water/salt-soluble protein (albumin/globulin) and water/salt-insoluble protein (gliadins and glutenins (Glu)) according to solubility. Gliadins (Glia) are one of the major allergens in wheat. The inhibition of Glia antigenicity by conventional processing techniques was not satisfactory. RESULTS: In this study, free radical oxidation was used to induce covalent reactions. The effects of covalent reactions by high-intensity ultrasound (HIU) of different powers was compared. The enhancement of covalent grafting effectiveness between gliadin and (-)-epigallo-catechin 3-gallate (EGCG) was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry and Folin-Ciocalteu tests. HIU caused protein deconvolution and disrupted the intrastrand disulfide bonds that maintain the tertiary structure, causing a shift in the side chain structure, as proved by Fourier, fluorescence and Raman spectroscopic analysis. Comparatively, the antigenic response of the conjugates formed in the sonication environment was significantly weaker, while these conjugates were more readily hydrolyzed and less antigenic during simulated gastrointestinal fluid digestion. CONCLUSION: HIU-enhanced free radical oxidation caused further transformation of the spatial structure of Glia, which hid or destroyed the antigenic epitope, effectively inhibiting protein antigenicity. This study widened the application of polyphenol modification in the inhibition of wheat allergens. © 2024 Society of Chemical Industry.

The Celiac-Disease Superantigen Oligomerizes and Increases Permeability in an Enterocyte Cell Model.

Celiac disease (CeD) is an autoimmune disorder triggered by gluten proteins, affecting approximately 1 % of the global population. The 33-mer deamidated gliadin peptide (DGP) is a metabolically modified wheat-gluten superantigen for CeD. Here, we demonstrate that the 33-mer DGP spontaneously assembles into oligomers with a diameter of approximately 24 nm. The 33-mer DGP oligomers present two main secondary structural motifs-a major polyproline II helix and a minor ß-sheet structure. Importantly, in the presence of 33-mer DGP oligomers, there is a statistically significant increase in the permeability in the gut epithelial cell model Caco-2, accompanied by the redistribution of zonula occludens-1, a master tight junction protein. These findings provide novel molecular and supramolecular insights into the impact of 33-mer DGP in CeD and highlight the relevance of gliadin peptide oligomerization.

Formation, structural characteristics and specific peptide identification of gluten amyloid fibrils.

This research investigates the formation of amyloid fibrils using enzymatically hydrolyzed peptides from gluten, including its components glutenin and gliadin. After completing the fibrillation incubation, the gluten group demonstrated the most significant average particle size (908.67 nm) and conversion ratio (57.64 %), with a 19.21 % increase in thioflavin T fluorescence intensity due to self-assembly. The results indicated increased levels of ß-sheet structures after fibrillation. The gliadin group exhibited the highest zeta potential (∼13 mV) and surface hydrophobicity (H0 = 809.70). Around 71.15 % of predicted amyloidogenic regions within gliadin peptides showed heightened hydrophobicity. These findings emphasize the collaborative influence of both glutenin and gliadin in the formation of gluten fibrils, influenced by hydrogen bonding, hydrophobic, and electrostatic interactions. They also highlight the crucial role played by gliadin with amyloidogenic fragments such as ILQQIL and SLVLQTL, aiming to provide a theoretical basis for understanding the utilization of gluten proteins.

Investigating the interaction mechanism between gliadin and lysozyme through multispectroscopic analysis and molecular dynamic simulations.

The development of stable nanocomplexes based on gliadin and other biopolymers shows potential applications as delivery vehicles in the food industry. However, there is limited study specifically targeting the gliadin-lysozyme system, and their underlying interaction mechanism remains poorly understood. Therefore, the objective of this study was to investigate the binding mechanism between gliadin and lysozyme using a combination of multispectroscopic methods and molecular dynamic simulations. Stable gliadin-lysozyme complex nanoparticles were prepared using an anti-solvent precipitation method with a gliadin-to-lysozyme mass ratio of 2:1 and pH 4.0. The characteristic changes in the UV-visible spectrum of gliadin induced by lysozyme confirmed the complex formation. The analyses of fluorescence, FT-IR spectra, and dissociation tests demonstrated the indispensability of hydrophobic, electrostatic, and hydrogen bonding interactions in the preparation of the composites. Scanning electron microscopy revealed that the surface morphology of the nanoparticles changed from smooth and spherical to rough and irregular with the addition of lysozyme. Furthermore, molecular dynamic simulations suggested that lysozyme bound to the hydrophobic region of gliadin and hydrogen bonding was crucial for the stability of the complex. These findings contribute to the advancement of gliadin-lysozyme complex nanoparticles as an efficient delivery system for encapsulating bioactive compounds in food industry.

Mass spectrometry-based quantification of immunostimulatory gliadin proteins and peptides in coloured wheat varieties: Implications for Celiac Disease.

Pigmented wheat varieties (Triticum aestivum spp.) are getting increasingly popular in modern nutrition and thoroughly researched for their functional and nutraceutical value. The colour of these wheat grains is caused by the expression of natural pigments, including carotenoids and anthocyanins, that can be restricted to either the endosperm, pericarp and/or aleurone layers. While contrasts in phytochemical synthesis give rise to variations among purple, blue, dark and yellow grain's antioxidant and radical scavenging capacities, little is known about their influence on gluten proteins expression, digestibility and immunogenic potential in a Celiac Disease (CD) framework. Herein, it has been found that the expression profile and immunogenic properties of gliadin proteins in pigmented wheat grains might be affected by anthocyanins and carotenoids upregulation, and that the spectra of peptide released upon simulated gastrointestinal digestion is also significantly different. Interestingly, anthocyanin accumulation, as opposed to carotenoids, correlated with a lower immunogenicity and toxicity of gliadins at both protein and peptide levels. Altogether, this study provides first-level evidence on the impact modern breeding practices, seeking higher expression levels of health promoting phytochemicals at the grain level, may have on wheat crops functionality and CD tolerability.

Optimized Chitosan-Coated Gliadin Nanoparticles Improved the Hesperidin Cytotoxicity over Tumor Cells

Abstract Hesperidin is a natural compound which is found in citric fruits and presents antitumor and antimicrobial activities. However, the in vivo efficacy of Hesperidin is reduced due to its low oral bioavailability. Protein-based nanoparticles have been applied to improve biological parameters of drugs and natural compounds. Gliadin is a monomeric protein present in wheat. In this study, gliadin-based nanoparticles containing hesperidin were obtained by desolvation technique and a Taguchi orthogonal array design was employed to optimize the formulation. The independent variables were set as concentration of CaCl2 (0.5; 1 or 2%) and stabilizing agent (Pluronic F68, Tween 80 or sodium caseinate). The dependent variables consisted of mean diameter, polydispersity index, zeta potential, and encapsulation efficiency. The results showed significant effects on the dependent variables when 1% CaCl2 and Pluronic F68 were used. The optimized formulation was coated with chitosan to increase the physical stability of the nanoparticles. The final nanoparticles presented a mean diameter of 321 nm and polydispersity index of 0.217, and spherical shape. After coating, the Zeta potential was +21 mV, and the encapsulation efficiency was 73 %. The in vitro release assay showed that about 98% of the drug was released from the nanoparticles after 48 h. Moreover, the nanoparticles reduced hesperidin cytotoxicity on healthy cells (Vero cells) and improved the cytotoxicity on tumor cells (HeLa, PC-3 and Caco-2 cells). Results showed that the chitosan-coated gliadin nanoparticles are potential carriers for hesperidin delivery for cancer treatment.