Dynamic distribution and transition of gluten proteins during noodle processing

Dynamic behaviors of protein and water associated with fresh noodle quality during processing based on different HMW-GSs at Glu-D1

In this study, dynamic behaviors of proteins and water during fresh noodles processing associated with the quality of fresh noodles were systematically investigated by using wheat near-isogenic lines carrying high-molecular-weight glutenin subunits (HMW-GS) 2 + 12, 3 + 12 or 5 + 10 at the Glu-D1 locus. The results showed that subunits 5 + 10 tend to form a complex gluten network and had a poorly hydrated ability, that prevent the intrusion of external water during cooking; subunits 3 + 12 formed a moderate strength gluten network that generated a medium ability to resist the hydrated and mechanical treatment, which explained the highest water absorption and less cooking loss of cooked noodles; while subunits 2 + 12 formed fragile protein aggregates that had a poor ability to resist mechanical. The findings demonstrated that subunits 3 + 12 provided a suitable gluten network which was crucial for intrusion and hydration of external water thus formed a uniform gluten network and excellent fresh noodle quality.

Heat-moisture treatment can modulate all-purpose wheat flour for short dough biscuit making: Evidences and mechanism

In view of the merits of all-purpose wheat flour (APWF) to soft wheat flour (SWF) in cost and protein supply, the feasibility of heat-moisture treatment (HMT, 19% moisture for 1 h at 60, 80 and 100 °C, respectively) to modify APWF as a substitute SWF in making short dough biscuits was explored. For underlying mechanisms, on the one hand, HMT reduced the hydration capacity of damaged starch particles by coating them with denatured proteins. On the other hand, HMT at 80 °C and 100 °C significantly denatured gluten proteins to form protein aggregates, highly weakening the gluten network in dough. These two aspects jointly conferred APWF dough with higher deformability and therefore significantly improved the qualities of biscuits. Moreover, the qualities of biscuits from APWF upon HMT-100 °C were largely comparable to that from SWF, even higher values were concluded in spread ratio, volume, specific volume and consumer acceptance.

Changes in rheology and components during the processing of Chinese traditional handmade hollow dried noodle

The study of the changes in rheological properties and components during the processing of Chinese traditional handmade hollow dried noodle (HHDN) is essential to explaining the excellent quality of HHDN. The dynamic oscillation frequency sweep, stress relaxation, and uniaxial extension characteristics of the dough after kneading, stretching, and resting were investigated at six sampling points during the processing of HHDN. The result showed that stretching led to an increase in G' and G0, and a significant decrease (P < 0.05) in extensibility from 131.02 mm to 57.99 mm. Confocal laser scanning microscopy (CLSM) was used to observe the microstructure of the gluten network, which was destroyed during stretching and restored during resting. Studies of changes in components showed that the stretching process resulted in a decrease in GMP content from 3.24 (g/100 g) to 3.18 (g/100 g), and the resting process resulted in β-sheets decreasing significantly (P < 0.05). The degree of starch pasting increased significantly (P < 0.05) after stretching. The results of the correlation analysis showed that components changes were highly correlated with the rheological properties during the processing of HHDN.

Folding during sheeting improved qualities of dried noodles through gluten network proteins

The texture properties after cooking for 12 min were selected to optimize the sheeting parameters, and the results were verified using the comprehensive quality of dried noodles. The distribution of water, characteristics of gluten protein, and interaction between gluten network and starch were analyzed to clarify the mechanism of the quality of dried noodles. Results showed that the optimal folding angle was 45°, under this condition, the largest anti-extension displacement perpendicular to the rolling direction and the smallest cooking loss were obtained. The hardness and smoothness of cooked noodles increased by about 14% to 17%. Further, the transverse relaxation time of strongly bound water significantly decreased, while the relative content and binding strength increased. The hydrogen bonds and α-helix contents increased by about 68.8% and 53.1%, respectively. Folding and sheeting enhanced the combination of starch granules and gluten network causing, decreased in the average length and porosity of the gluten network. It is depicted from the results that the method of optimizing the sheeting process based on the texture of dried noodles cooked for 12 min was feasible. And the 45° folding and sheeting could help to improve the quality of dried noodles.

Effect of sanxan on the composition and structure properties of gluten in salt-free frozen-cooked noodles during freeze-thaw cycles

In this study, the mechanisms by which sanxan protected the quality of salt-free frozen-cooked noodles (SFFCNs) were investigated, with a focus on the composition and structural properties of gluten. The results showed that sanxan facilitated the formation of glutenin macropolymer and maintained the stabilization of glutenin subunits in freeze-thaw cycles (FTs). In terms of protein structure, sanxan weakened the disruption of secondary structure caused by FTs and increased the proportion of gauche-gauche-gauche (g-g-g) conformations in the disulfide (S-S) bonds bridge conformation. Simultaneously, sanxan reduced the exposure degree of tryptophan (Trp) and tyrosine (Tyr) residues on the protein surface. Moreover, the intermolecular interaction forces indicated that sanxan inhibited S-S bonds breakage and enhanced the intermolecular crosslinking of gluten through ion interactions, which was crucial for improving the stability of gluten. This study provides a more comprehensive theoretical basis for the role of sanxan in improving the quality of SFFCNs.

Retrogradation-induced physicochemical changes in pre-cooked rice noodles stored at different temperatures: a viewpoint from water dynamics and structure

BACKGROUND

There has been significant interest in pre-cooked noodles that have a long shelf life and are convenient to cook. However, the thermal processes during preparation, and their high moisture content, can lead to significant quality deterioration during storage. Nevertheless, a comprehensive evaluation of these quality losses has not yet been conducted.

RESULTS

The effects of different storage temperatures (25, 4, and -20 °C) on the retrogradation-related physicochemical changes in pre-cooked rice noodles were elucidated mainly from the water dynamics and structural viewpoints. Thermal analysis demonstrated that amylopectin recrystallization took place in the noodles stored at refrigerated temperature, followed by room temperature. The refrigerated storage accelerated the starch retrogradation that caused the water molecules to become entrapped within the crystalline structure by lowering the water hydration properties and weighted T2 relaxation times of the pre-cooked noodles. These water mobility patterns were correlated with the textural changes in the noodles (greater hardness and Rmax /extensibility). Furthermore, the higher structural density and thickness derived from starch retrogradation were observed in the tomographic and microscopic images of the refrigerated noodles. The principal component analysis demonstrated that various physicochemical changes of the pre-cooked noodles during storage showed high correlations with the degree of starch retrogradation (r > 0.83).

CONCLUSION

The physicochemical features of the precooked noodles stored under refrigerated conditions were involved in the molecular dynamics of water, showing a notable water mobility reduction derived from the starch retrogradation, which contributed to their thermal, tomographical, and textural changes. © 2023 Society of Chemical Industry.

Real-Time Monitoring of Dough Quality in a Dough Mixer Based on Current Change

Accurate assessment of dough kneading is pivotal in pasta processing, where both under-kneading and over-kneading can detrimentally impact dough quality. This study proposes an innovative approach utilizing a cost-effective current sensor to ascertain the optimal kneading time for dough. Throughout the kneading process, the dough's tensile resistance gradually increases, reflecting the evolution of properties such as the gluten network. This leads to a discernible ascending phase in dough quality, evident through an increase in the load current of the mixing machine, succeeded by a subsequent decline beyond a certain threshold. The identification of this peak point enables the achievement of optimal dough consistency, thereby enhancing the overall quality of both the dough and subsequent pasta products. After the final product quality assessment, this novel method promises to be a valuable tool in optimizing pasta processing and ensuring consistent product quality.

Effect of egg white protein on the protein structure of highland barley noodles during processing

The effect of egg white protein on the protein structure of highland barely noodles during processing was investigated, and the underlying mechanism was examined. Egg white protein significantly influenced the stress relaxation of highland barley dough. 1% and 2% egg white protein improved the cooking and textural properties of highland barely noodles. During mixing and sheeting, it improved the structure of the protein network by promoting protein aggregation and cross-linking, whereas its effect on non-covalent interactions was quite different. During cooking, egg white protein promoted protein aggregation and cross-linking via heat-induced polymerization, and the distribution regularity of the protein network was improved as its flexibility diminished. The protein structure of highland barely noodles during processing was closely related to the addition amount of egg white protein, and the cooking, textural, and chemical interactions of highland barely noodles during processing changed considerably when more than 3% egg white protein was added.

Impact of wheat bran dietary fiber on gluten aggregation behavior in dough during noodle processing

We herein evaluated the impact of adding wheat bran dietary fiber (WBDF) on the aggregation behavior of gluten in dough at various stages of the noodle-making process. Scanning electron microscopy and confocal laser scanning microscopy images confirmed the effective insertion of WBDF particles into the gluten matrix. Importantly, the gap between WBDF and gluten widened during the rolling process. The addition of WBDF led to a reduction in glutenin macropolymer (GMP) content and an elevation in sulfhydryl content, induced the depolymerization behaviors at the molecular level. Additionally, it facilitated the conversion of α-helices and β-turns into β-sheets and random coils within the dough. Moreover, the processing and addition of WBDF contributed to a decrease in weight loss, whereas the degradation temperature remained constant. Resting decreased the sulfhydryl content, whereas sheeting and cutting increased it, further fostering protein depolymerization in the presence of WBDF. These actions significantly increased the β-sheets and random coils content at the expense of β-turns and α-helices content. Significantly, controlled processing emerged as a crucial factor in enhancing gluten depolymerization induced by WBDF in the dough. This comprehensive study provides a nuanced perspective on controlling dough processing to strike a balance between dietary fiber-rich and high-quality foods.

Changes in Cooking Characteristics, Structural Properties and Bioactive Components of Wheat Flour Noodles Partially Substituted with Whole-Grain Hulled Tartary Buckwheat Flour

The whole-grain, hulled Tartary buckwheat flour (HTBF) with outstanding bioactive functions was prepared, and the effects of partial substitution ratios (0, 30%, 51% and 70%) of wheat flour with HTBF on the characteristics of TB noodles (TBNs) were investigated, mainly including the cooking characteristics, sensory analysis, internal structure, bioactive components, and in vitro starch digestibility. With an increasing replacement level of HTBF, the water absorption index of the noodles decreased, whereas the cooking loss increased. A sensory analysis indicated that there were no off-flavors in all TBN samples. The scanning electron microscope images presented that the wheat noodles, 30% TBNs and 70% TBNs had dense and uniform cross sections. Meanwhile, the deepest color, V-type complexes, and lowest crystallinity (13.26%) could be observed in the 70% TBNs. A HTBF substitution increased the rutin content and the total phenolic and flavonoid contents in the TBNs, and higher values were found in the 70% TBNs. Furthermore, the lowest rapidly digestible starch content (16%) and highest resistant starch content (66%) were obtained in the 70% TBNs. Results demonstrated that HTBF could be successfully applied to make TBNs, and a 70% substitution level was suggested. This study provides consumers with a good option in the realm of special noodle-type products.

Enzymatic Preparation and Processing Properties of DPP-IV Inhibitory Peptides Derived from Wheat Gluten: Effects of Pretreatment Methods and Protease Types

The choice of appropriate proteases and pretreatment methods significantly influences the preparation of bioactive peptides. This study aimed to investigate the effects of different pretreatment methods on the hydrolytic performance of diverse proteases during the production of dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides derived from wheat and their foaming and emulsion properties. Dry heating, aqueous heating, and ultrasound treatment were employed as pretreatments for the protein prior to the enzymatic hydrolysis of wheat gluten. FTIR analysis results indicated that all pretreatment methods altered the secondary structure of the protein; however, the effects of dry heating treatment on the secondary structure content were opposite to those of aqueous heating and ultrasound treatment. Nevertheless, all three methods enhanced the protein solubility and surface hydrophobicity. By using pretreated proteins as substrates, five different types of proteases were employed for DPP-IV inhibitory peptide production. The analysis of the DPP-IV inhibitory activity, degree of hydrolysis, and TCA-soluble peptide content revealed that the specific pretreatments had a promoting or inhibiting effect on DPP-IV inhibitory peptide production depending on the protease used. Furthermore, the pretreatment method and the selected type of protease collectively influenced the foaming and emulsifying properties of the prepared peptides.

Effect of different enzymes on thermal and structural properties of gluten, gliadin, and glutenin in triticale whole-wheat dough

Three enzymes promoted the development of the gluten network in triticale whole-wheat noodles (TWWN). To further understand the mechanism of gluten enhancement, the effects of three enzymes on the structure of gluten and its fractions (gliadin and glutenin) were evaluated. The results showed that glucose oxidase (GOD), xylanase (XYL), and laccase (LAC) decreased the content of sodium dodecyl sulfate (SDS) extractable proteins. The content of glutenin subunits was reduced by 17.25 %, 30.60 %, and 20.09 % with the addition of GOD, XYL, and LAC, respectively. Furthermore, GOD and LAC increased the content of glutenin macropolymer (GMP) by 2.64 % and 7.71 %, respectively, suggesting the promotion of glutenin aggregation. The addition of three enzymes decreased the weight loss and increased the degradation temperature of the gluten and its fractions. GOD and XYL decreased the fluorescence intensity of gluten and its fractions, except for XYL which increased the fluorescence intensity of glutenin by 10.50 %. Intermolecular interactions and surface hydrophobicity were enhanced by XYL in gluten and its fractions. GOD and LAC decreased the free sulfhydryl content and increased the β-sheet content, suggesting that the covalent interaction between gluten fractions was enhanced. Therefore, this research can enrich the theoretical study of enzymatic cross-linking.

Interaction with wheat starch affect the aggregation behavior and digestibility of gluten proteins

Understanding the interplay between gluten and wheat starch is crucial for elucidating the digestibility mechanism of gluten in wheat-based products. However, this mechanism remains under-investigated. This study sought to elucidate the influence of starch-induced protein structural modifications on gluten digestion. Our findings revealed that starch considerably enhanced gluten digestion. In the presence of starch, gluten protein digestibility increased from 10.91 % (in the control group with a gluten-to-starch ratio of 1:0) to 14.40 % (in the complex with a gluten-to-corn starch ratio of 1:1). The diminished gluten protein digestibility due to starch may be ascribed to modifications in protein configuration and aggregation behavior. Morphological studies suggested that starch not only functioned as filler particles but also diluted the gluten matrix. A protein network assessment further affirmed that both the junction density and branching rate of gluten proteins decreased notably by 29.9 % and 25.1 %, respectively. Conversely, lacunarity increased by 1.92-fold, compromising the cohesiveness and connectivity of the gluten matrix. Elevated starch concentrations suppressed the formation of disulfide bonds, impeding gluten protein aggregation. Concurrently, gluten-starch interactions were governed by hydrogen bonds and hydrophobic associations. In summary, starch augmented gluten protein digestibility by curtailing their polymerization. This revelation might offer novel perspectives on optimizing gluten protein digestion and utilization.

Effect of sodium carbonate on the properties of seventy percent of Tartary buckwheat composite flour-based doughs and noodles and the underlying mechanism

The impact of Na2 CO3 on the properties of doughs and noodles containing 70% Tartary buckwheat flour was investigated. Low-field 1 H nuclear magnetic resonance showed the mobility of water in the doughs significantly declined with the addition content of alkali from 0% to 0.9%. Na2 CO3 promoted the transformation from free sulfhydryl groups to disulfide bonds in doughs because the sulfhydryl groups in cysteine preferred to form thiolate anion and then oxidate under alkaline conditions. As for non-covalent chemical interactions, a significant increase of hydrogen bonds and a decrease of hydrophobic interactions were observed after Na2 CO3 addition. Quantitative analysis of microstructure showed that more uniform and denser gluten networks with higher branching rate and shorter average protein length and width formed in the doughs with 0.3%-0.6% of Na2 CO3 . The aggregated glutenin macropolymer and enhanced protein structure led to significantly stronger tensile of Tartary buckwheat dough sheets, which could meet the demand of continuous processing in the factory. Dough with alkali had higher swelling power and pasting viscosities, contributing to higher water absorption, and improved textural attributes of cooked noodles. This study demonstrated the possibility of adding Na2 CO3 at a moderate level for promoting the sheeting, cooking, and eating properties of high Tartary buckwheat flour composite noodles.

The Role of Gluten in Food Products and Dietary Restriction: Exploring the Potential for Restoring Immune Tolerance

Wheat is extensively utilized in various processed foods due to unique proteins forming from the gluten network. The gluten network in food undergoes morphological and molecular structural changes during food processing, affecting the final quality and digestibility of the food. The present review introduces the formation of the gluten network and the role of gluten in the key steps of the production of several typical food products such as bread, pasta, and beer. Also, it summarizes the factors that affect the digestibility of gluten, considering that different processing conditions probably affect its structure and properties, contributing to an in-depth understanding of the digestion of gluten by the human body under various circumstances. Nevertheless, consumption of gluten protein may lead to the development of celiac disease (CD). The best way is theoretically proposed to prevent and treat CD by the inducement of oral tolerance, an immune non-response system formed by the interaction of oral food antigens with the intestinal immune system. This review proposes the restoration of oral tolerance in CD patients through adjunctive dietary therapy via gluten-encapsulated/modified dietary polyphenols. It will reduce the dietary restriction of gluten and help patients achieve a comprehensive dietary intake by better understanding the interactions between gluten and food-derived active products like polyphenols.

Effects of quinoa flour (Chenopodium Quinoa Willd) substitution on wheat flour characteristics

Quinoa is a pseudo-cereal with great nutritional and functional qualities, serving as an excellent substitution to develop quinoa-containing foods. This study aimed to explore the influence of quinoa flour substitution on quality characteristics of wheat flour (WF). WF was substituted with different level of quinoa core flour, ground quinoa whole flour and recombined quinoa whole flour. Increasing levels of quinoa flour in WF declined dough swelling index, while increased falling number of composite flours. Besides, quinoa flour substitution considerably decreased the chemical forces of gluten in composite flours. The proportions α-helix and β-sheets reduced, while the random coil proportion increased in gluten secondary structure. SEM images revealed that the gluten network structure was severely damaged. Our findings indicated that substitution of WF with quinoa flours was promising to be developed as an ingredient for food products.

Effect of honeysuckle leaf extract on the physicochemical properties of carboxymethyl konjac glucomannan/konjac glucomannan/gelatin composite edible film

Honeysuckle leaves are rich in bioactive ingredients, but often considered as agro-wastes. In this study, honeysuckle leaf extract (HLE) was added to the carboxymethyl konjac glucomannan/konjac glucomannan/gelatin composite edible film (CMKH). Compared to films without HLE addition (CMK), the water vapor barrier properties of CMKH slightly decreased, but the transmittance of the CMKH films in UV region (200-400 nm) as low as zero. The elongation at break of CMKH film was 1.39 ∼ 1.5 fold higher than those of CMK films. The DPPH and ABTS scavenging activity of CMKH-Ⅱ was 85.75% and 90.93%, respectively, which is similar to the equivalent content of Vc. The inhibition rate of CMKH-Ⅰ and CMKH-Ⅱ against Escherichia coli and Listeria monocytogenes were close to 90%, and the inhibition rate against Staphylococcus aureus were up to 96%. The results emphasized that the composite film containing 25% (v/v) HLE has potential application value in food preservation.

Wheat starch particle size distribution regulates the dynamic transition behavior of gluten at different stages of dough mixing

This study investigated the morphology distribution, molecular structure, and aggregative properties variation of gluten protein during dough mixing stage and interpreted the interaction between starch with different sizes and protein. Research results indicated that mixing process induced glutenin macropolymer depolymerization, and promoted the monomeric protein conversion into the polymeric protein. Appropriate mixing (9 min) enhanced the interaction between wheat starch with different particle sizes and gluten protein. Confocal laser scanning microscopy images showed that a moderate increase in B-starch content in the dough system contributed to forming a more continuous, dense, and ordered gluten network. The 50A-50B and 25A-75B doughs mixed for 9 min exhibited a dense gluten network, and the arrangement of A-/B-starch granules and gluten was tight and ordered. The addition of B-starch increased α-helixes, β-turns, and random coil structure. Farinographic properties indicated that 25A-75B composite flour had the highest dough stability time and the lowest degree of softening. The 25A-75B noodle displayed maximum hardness, cohesiveness, chewiness, and tensile strength. The correlation analysis indicated that starch particle size distribution could influence noodle quality by changing the gluten network. The paper can provide theoretical support for regulating dough characteristics by adjusting the starch granule size distribution.

Wakame replacement alters the metabolic profile of wheat noodles after in vitro digestion

The development of nutritional noodles of high quality has become a new hotspot of research in the area of food science. Since wakame is edible seaweed rich in dietary fiber and proteins and rarely found in ordinary noodle, this study investigated the release of metabolites, the texture quality, and the rheological properties of wakame noodle, as well as the mechanism by which extruded wakame flours can influence noodle texture and viscoelasticity through digestion. Basically, nuclear magnetic resonance spectra were applied to identify the 46 metabolites including amino acids, saccharides, fatty acids, and other metabolites. Both PCA and OPLS-DA model showed fit goodness and good predictivity, which were assessed the increasing release of most metabolites. Structural studies discussed the effects on the enhancement of interlinkage with gluten matrix and protein matrix, which were validated via the decreasing instantaneous compliance J0 (1.64 × 10-5 to 0.16 × 10-5 Pa-1). Wakame addition best matched the physiochemical properties of noodle, in terms of chewiness (99.10 vs 122.66 g.mm), gumminess (281.98 vs. 323.44 g), and gel strength (132.65 vs 173.95 kPa•s-1). Beyond the functional characteristics it contributes benefits like reduction of diet-related diabetes. As a consequence, the creation of personalized nutritious, healthy noodles will be an innovative route from a scientific viewpoint and an application standpoint.

Investigating the positive effects of wrap-around resting on the qualities of semi-dried noodles through the quantitative analysis of gluten network

In this study, the dough sheet wrap-around was employed to assist the resting process of the semi-dried noodles comparatively with dough crumbs resting and common dough sheet resting. The gluten network quantitative analysis was carried out to investigate the positive impacts of dough sheet wrap-around resting in semi-dried noodles production. The results showed that the dough sheet wrap-around resting improved the color, surface smoothness, cooking qualities, and eating qualities of semi-dried noodles. Dough sheet wrap-around resting for 30 min significantly (p < 0.05) increased the surface smoothness and chewiness by 47.08% and 44.35%, respectively. Furthermore, increased extensibility in the transverse direction of dough sheets generated superior processing properties. The average protein length and width of dough sheets experienced a considerable (p < 0.05) reduction. In contrast, the branching rate was markedly (p < 0.05) augmented, which meant the distribution of gluten network was more uniform and denser. The total protein length and the number of protein network lines both significantly (p < 0.05) increased. The number of transverse protein network lines increased by 28.70%, which was much higher than that (5.77%) of the longitudinal direction. Conclusively, at the optimal dough sheet wrap-around time of 30 min, the higher-quality semi-dried noodles were produced by enhancing the gluten network.

Effect of White Kidney Bean Flour on the Rheological Properties and Starch Digestion Characteristics of Noodle Dough

The aim of this study was to investigate the effect of adding white kidney bean flour on the quality of noodles. We selected four different proportions of white kidney bean flour (10−40%) in wheat flour to make the noodles, after which the noodles were analysed for their physical and chemical properties. The statistical method of correlation analysis was used in this study. The results showed that the noodles’ sensory and textural characteristics significantly improved after adding white kidney bean flour (p < 0.05). Compared with the control, the noodles’ surface with white kidney bean flour was denser and smoother. Moreover, microstructural observations indicated that the noodles with white kidney bean flour showed a more continuous protein network. The in vitro digestion results showed that the addition of white kidney bean flour reduced the digestibility of the noodles. Low addition of the flour (10−20%) improved the quality of the noodles, whereas high amounts (30−40%) showed the opposite effect. In this study, the optimal amount of white kidney bean powder was found to be 20%.

Characteristics of the enzyme-induced release of bitter peptides from wheat gluten hydrolysates

Bitter peptides in the enzymatic hydrolysates were prepared and purified from wheat gluten using aqueous ethanol solutions and macroporous resin, which has opened a new road for the extraction and separation of bitter peptides. This report contains the release regularity of bitter peptides and the factors affecting the change of bitter intensity during enzymatic hydrolysis, providing a scientific basis for the research on debitterizing method. In this study, the effects of different degrees of hydrolysis (DH) and enzyme active sites on the bitter peptide content and bitter taste thresholds were discussed. The relationship between amino acid composition, molecular weight distribution, surface hydrophobicity and bitter taste thresholds was extensively researched. The results showed the exposure of hydrophobic amino acids and the bitterness intensity of the hydrolysates increased as the DH increased, and the bitterness of wheat gluten hydrolysates (WGHs) hydrolyzed by Alcalase was stronger than that of Trypsin. According to correlation analysis, the proportion of total hydrophobic amino acid is the first factor that affects the sensory properties of bitter peptide, and the release content of bitter peptides and the content of total bitter amino acids are the second, following by the content of peptide in the molecular weight range of 500–1,000 Da and the surface hydrophobicity. The amino acid sequence of bitter peptides from WGHs were identified and predicted using high performance liquid chromatography-mass spectrometry (HPLC-MS/MS) and bioinformatics. It was found that the molecular weight of most of the peptides was below 1,500 Da, and the Q value was higher than 5.86 kJ/mol.

Evolution of the morphological, structural, and molecular properties of gluten protein in dough with different hydration levels during mixing

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Changes in hydration level induced different gluten evolution patterns and dynamics.

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Appropriate mixing at high hydration levels results in a more uniform gluten network.

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Gluten network in highly hydrated dough was more susceptible to mechanical force.

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High hydration level induced more ordered conformation and depolymerization of GMP.

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PCA and CA revealed that hydration level has more influence than mixing degree.

To understand the formation process of dough with different hydration levels upon mixing and the response of dough rheology, the dynamic evolution of gluten protein was tracked and quantified at morphological, structural, and molecular levels. Both macroscopical and microscopic distribution images showed that partial and full hydration induced quick formation of a more compact gluten network compared with limited hydration. Gluten network in highly hydrated samples was more susceptible to the formation and collapse induced by mechanical force. SE-HPLC results indicated significant depolymerization of glutenin macropolymer (GMP) in fully and partially hydrated samples. Sufficient mixing was accompanied by the increase of ionic and hydrogen bonds, while excessive mixing increased exposure of free -SH. Higher hydration level induced more ordered secondary structure. Correlation and principal component analysis revealed the patterns and dynamics of gluten evolution during dough formation with different hydration levels, and their contribution to the changes in dough modulus.

Delineating the dynamic transformation of gluten morphological distribution, structure, and aggregation behavior in noodle dough induced by mixing and resting

To understand the formation of gluten network and its regulation on noodle qualities upon mixing and resting, the dynamic distribution and molecular transformation of gluten were tracked and quantified. Confocal laser scanning microscopy and scanning electron microscopy images showed that appropriate mixing (8 min) and resting (60 min) induced a compact gluten network with higher gluten junctions. Both height and width of protein molecular chains were increased by hydration during mixing and reduced after excessive resting (90 min). According to the size exclusion/reversed phase-HPLC profiles, mixing induced slight depolymerization of large glutenin polymer, and α-gliadin subunits were more susceptible to polymerization after appropriate mixing and resting. Increased mixing time was accompanied by the strengthening of ionic and hydrogen bonds, and the weakening of hydrophobic interaction. PCA and correlation analysis revealed the accurate regulation of mixing and resting induced dynamic distribution and evolution of gluten on the macroscopic noodle qualities.

Study of Noodle Quality Based on Protein Properties of Three Wheat Varieties

Waxy wheat offers unique benefits in food processing, including improving the smoothness and performance of the product. However, waxy wheat is not yet commercially available. The protein characteristics, including the protein content, subunit distribution, secondary structure, chemical interactions, and microstructure of the gluten, were explored to realize the full potential of waxy wheat. The results showed that the noodles prepared from waxy wheat had a gentle and glutinous texture compared with GY2018 and YM13. Partial-waxy and waxy wheat had a lower gluten index and glutenin macropolymer (GMP) content than GY2018, indicating a reduced gluten strength. Confocal laser scanning microscopy (CLSM) images showed that the starch granules were not securely attached to the partial-waxy and waxy wheat protein matrix. In addition, the waxy protein chains appeared more elongated and they weakened the protein network. In particular, HMW-GS subunit 2 + 12 may be the essential cause of the weak dough from SKN1. Compared with GY2018 and YM13, SKN1 had the highest number of free sulfhydryl groups. Rather than ionic bonds, hydrophobic interactions increased the gluten network in GY2018, YM13, and SKN1. The weak molecular forces in the gluten will result in a soft noodle texture.

Screening of Sourdough Starter Strains and Improvements in the Quality of Whole Wheat Steamed Bread

In this study, yeast, lactic acid bacteria, and acetic acid bacteria were isolated from traditional Chinese sourdough to enhance the organoleptic quality of whole wheat steamed bread. The Saccharomyces cerevisiae, Lactobacillus johnsonii, and Acetobacter pasteurianum showed superior fermentability and acid production capacity when compared with other strains from sourdough, which were mixed to produce the compound starter. It was found that the volume of whole wheat steamed bread leavened with compound starter increased by 12.8% when compared with that of the whole wheat steamed bread made by commercial dry yeast (DY-WB). A total of 38 volatile flavors were detected in the whole wheat steamed bread fermented by the compound starter (CS-WB), and the type of volatile flavors increased by 14 species when compared to the bread fermented by the dry yeast. In addition, some unique volatile flavor substances were detected in CS-WB, such as acetoin, 3-hydroxy-butanal, butyraldehyde, cuparene, etc. Moreover, the hardness and the chewiness of CS-WB decreased by 31.1 and 33.7% when compared with DY-WB, respectively, while the springiness increased by 10.8%. Overall, the formulated compound starter showed a desirable improvement in the whole wheat steamed bread and could be exploited as a new ingredient for steamed bread.

Evaluation of the Storage Stability and Quality Properties of Fresh Noodles Mixed with Plasma-Activated Water

Enhancing the quality retention of fresh noodles remains challenging. In this study, we investigated the effect of dough mixing with plasma-activated water (PAW) of different activation times on the storage stability and quality characteristics of fresh noodles. It was found that the total plate count in the fresh noodles prepared by PAW (PAWN) showed no obvious inhibition during storage at 25 °C, but could be significantly reduced at 4 °C as compared with the control. The decrease in L* value and pH of the PAWN was significantly retarded during storage, indicating an enhanced storage stability. The stability time of dough mixed with PAW could be significantly improved. PAW treatment decreased the viscosity properties and setback value of starch, while enhancing the interaction of water and non-water components in fresh noodles. In addition, dynamic polymerization and depolymerization of proteins were detected in Size-Exclusion High-Performance Liquid Chromatography (SE-HPLC) profiles of PAWN. The hardness and adhesiveness of the cooked noodles decreased, while the springiness significantly increased. These results implied the potential of PAW in improving the storage stability and quality of fresh noodles.