Adlay starch-gluten composite gel: Effects of adlay starch on rheological and structural properties of gluten gel to molecular and physico-chemical characteristics

Biodegradable and antibacterial edible films based on egg yolk granules/gelatin/CMC with e-poly-l-lysine: Application in fresh chicken meat preservation

Novel biodegradable and antibacterial edible films were fabricated by incorporating E-poly-l-lysine (EPL) into egg yolk granules, gelatin, and sodium carboxymethyl cellulose matrices. With increasing EPL concentration (0.3-0.9 %), water vapor permeability decreased to 0.215 ± 0.005 g.mm/m2.h.Kpa, while the water contact angle increased to 79.8°, enhancing transparency. X-ray diffraction, attenuated total reflectance-Fourier transform infrared spectroscopy, and scanning electron microscopy revealed the uniform dispersion of the EPL in the matrix, likely due to enhanced intermolecular interaction. The 0.9 %-EPL film exhibited strong antimicrobial activity and biodegraded in soil within seven days. Additionally, chicken meat packaged with films was stored at 4 °C for 8 days. Results showed that the 0.9 %-EPL film significantly reduced the thiobarbituric acid reactive substances, pH, and total viable count, thereby extending its shelf life. In summary, the EPL-enhanced egg yolk granules/gelatin/CMC edible film exhibits significant potential as an eco-friendly antimicrobial packaging material.

β-Cyclodextrin/resistant dextrin induced disparate gelling behaviors of high-protein liquid systems

High-protein, high-fiber foods are in the spotlight because of their health properties. Due to aggregation during heat treatment when dietary fiber is added, the amount of soy protein that can be used in the formulation of high-protein, high-fiber foods is limited. The effects of two types of soluble dietary fibers, β-cyclodextrin (β-CD) and resistant dextrin (RD), on the tunable thermal stability of soy proteins (SPs) and preheat-modified soy protein particles (SPPs), as well as the underlying mechanisms, were investigated. Results showed that β-CD (0.5-3.0 %, w/v) weakened the gels and introduced some degree of mobility, while RD (0.5-3.0 %, w/v) increased the gel strength and viscoelastic properties of SP and SPP gels. Dynamic light scattering analysis revealed that β-CD mitigated the increase in particle size of SPs and SPPs during heating, delaying gel formation at high protein concentrations. In contrast, RD promoted protein agglomeration into larger particles, speeding up the gelation process. Structural analysis revealed that β-CD preserved the integrity of protein structure, while RD promoted the unfolding of protein structure, leading to protein cross-links and aggregation formation. In summary, the effect of β-CD and RD on soy protein thermal stability provides valuable insights for developing new health-focused, high-protein, high-fiber products.

Effect of exogenous protein crosslinking on the physicochemical properties and in vitro digestibility of corn starch

Starch is a primary energy source of human diet. Its physicochemical properties and digestibility can be improved by incorporating exogenous protein. In this study, mung bean protein isolate was covalently crosslinked using transglutaminase and proanthocyanidin to create crosslinked mung bean protein isolate. This modified protein was combined with corn starch to form crosslinked mung bean protein isolate-corn starch composite samples. Results demonstrated that these composite samples exhibited superior physicochemical properties, including reduced swelling capacity, enhanced freeze-thaw stability, improved thermostability, and enhanced antioxidant properties. During in vitro digestion, the improved corn starch digestibility was attributed to two factors: first, hydrogen bonding and electrostatic interactions between crosslinked mung bean protein isolate and corn starch; and second, the synergistic crosslinking of transglutaminase and proanthocyanidin promoting the formation of a stable protein network of mung bean protein isolate, serving as a physical barrier to protect corn starch. After co-treatment with transglutaminase and proanthocyanidin, significant changes of mung bean protein isolate occurred in their secondary and tertiary structures, enhancing its protein network strength, thereby improving the physicochemical properties of corn starch. These findings propose a new strategy for reducing rapidly digestible starch and provide a theoretical foundation for developing low glycemic index starch foods.

Regulation of ice crystal growth in frozen dough: From the effect of gluten and starch fractions interaction on water binding - A review

The formation and growth of ice crystals are critical factors affecting the quality of frozen dough. Gluten and starch are the primary components of dough, and their hydration properties and effects on dough structure are crucial in determining the type of ice crystals formed. Gliadins, glutenins, A-type starch, and B-type starch are their refined components, each with distinct hydration properties and impact on dough structure. This review examines the structural properties and hydration properties of protein and starch components in frozen dough, as well as their individual and interactive influences on water absorption and the structural properties of frozen dough. Additionally, it explores changes at different structural levels during the interaction between protein and starch components in frozen dough. The review provides theoretical support for wheat breeding aimed at frozen flour products, ultimately contributing to the improvement of frozen dough quality and final product outcomes.

Effects of thermal treatment and Glucono-δ-lactone on the quality of alkaline dough and steamed buns

In the present study, the effects of glucono-δ-lactone (GDL) as an acid reagent during thermal treatment on the quality of alkaline dough and steamed buns were examined. During the heating process, GDL improved the viscoelasticity and fluidity of the alkaline dough and enhanced intermolecular hydrogen bonding. The hardness of steamed buns was reduced by 61.04 %, whereas the specific volume was increased by 10.4 % with 0.8 g of GDL. The color and taste were also improved to a certain extent. Scanning electron microscopy revealed that excessive GDL caused the dissolution of the gluten network and reduced the formation of gluten protein aggregates. During the heating process, GDL is beneficial to the aggregation of the gluten network. During the process of heating from 25 °C to 60 °C, GDL reduced the -SH content and zeta potential in gluten proteins, enhanced thermal stability, and formed a more ordered gluten network. Excessive GDL reduces the pH of the system by approximately 50 %, causing gluten network dissolution and the reduced formation of gluten protein aggregates. When the temperature increased from 60 °C to 95 °C, a stable gluten network system was formed inside the alkaline dough, and GDL changed the pH of the dough by reacting with sodium bicarbonate, resulting in greater elasticity and lower hardness of the dough. These results provide a theoretical basis for using GDL as an acid reactant for chemical fermentation.

Moderately mechanically activated starch in improving protein digestibility: Application in noodles

The aim of this study was to investigate the mechanism of protein digestibility improvement by exploring the changes in structural characteristics of proteins in noodles with varying levels of mechanically activated starch. Therefore, different levels of mechanically activated wheat starch were mixed with refined wheat flour to produce noodles. Results showed that moderately mechanically activated starch could significantly improve protein digestibility and noodles containing 8.76 % damaged starch exhibited the highest protein digestibility of 88.97 %. This enhancement was due to the ability of moderately mechanically activated starch to hinder the cross-linking of γ-gliadin, D-LMS, and B/C-LMS via disulfide bonds and promote the transition from β-sheets to β-turns. Additionally, moderately mechanically activated starch induced protein unfolding by decreasing the α-helix content and facilitating the transformation from g-g-g to t-g-t conformations, thereby increasing the accessibility of enzymatic hydrolysis sites. However, excessively mechanically activated starch induced protein folding, as evidenced by an increase in the g-g-g conformations content and protein width (11.10), thus slightly reducing protein digestibility to 82.39 % in noodles containing 10.62 % damaged starch. Thus, the results of this study may provide new insights for the development of formulated foods with high protein digestibility for consumers in areas with limited economic resources.

Characteristics of OSA modified starch-based Pickering emulsion and its application to myofibrillar protein gel

BACKGROUND

Pickering emulsions prepared with octenyl succinic anhydride-modified starch (OSAS) show significant promise as replacements for animal fat. However, the underlying mechanism of incorporating an OSAS-based Pickering emulsion into a myofibrillar protein (MP) gel and its impact on the gel properties remain poorly understood. In this study, the effects of OSAS at varying concentrations (0-10.0 g kg-1) on the stability of Pickering emulsion and the resultant gel properties of MP were investigated.

RESULTS

Emulsion stability was assessed using a stability analyzer, revealing a significant enhancement with increasing OSAS concentration. Compared with MP gel, the incorporation of the OSAS-based Pickering emulsion markedly improved the texture of the composite gels, increasing the gel hardness from 0.28 to 0.66 N. Moreover, water-holding capacity of composite gels rose from 28.5% to 61.2%, with a notable increase in immobilized water and a decrease in mobilized water. Rheological analysis revealed that the interactions of modified starch with MP and water molecules bolstered the elastic modulus of the gels. Additionally, the presence of OSAS-stabilized emulsions led to reduced surface hydrophobicity and sulfhydryl content of proteins in the gels, while partially inhibiting protein oxidation.

CONCLUSION

OSAS, notably at a high concentration, improved the physical stability of Pickering emulsion and the properties of MP gel. This research provides fundamental insights for the development of high-quality emulsified meat products. © 2024 Society of Chemical Industry.

Enhancement of gluconolactone-induced soybean protein isolate gels by low concentrations of oxidized konjac glucomannan: Gel properties and microstructure

Gluconolactone (GDL) induces soybean protein isolate (SPI) gelation by gradually releasing H+, lowering the pH to promote protein aggregation. However, excessive GDL often lead to an undesirable acidic taste in food gels. This study evaluated the effects of oxidized konjac glucomannan (OKGM) and varying H+ release levels on SPI gel properties, aiming to enhance gel quality while reducing GDL dependency. Results demonstrated that OKGM significantly improved gel texture and viscoelasticity, with low concentrations (0.5-1.5%, w/v) promoting SPI aggregation and forming a denser, more elastic gel network. Notably, OKGM accelerated the gelation process, reducing the gelation time from 12.88 ± 0.14 to 11.26 ± 0.00 min, while also increasing gel strength and stability. Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) revealed that OKGM interacted with SPI through Schiff-base reactions, enhancing thermal stability. However, at high OKGM concentrations (2.0-2.5%, w/v), thermodynamic incompatibility led to phase separation, increasing surface hydrophobicity and free sulfhydryl content, which disrupted gel uniformity. Overall, OKGM synergized with GDL to induce gelation, enabling a reduction in acid coagulant usage while enhancing gel quality. This study provides a novel approach to designing low-calorie, fiber-rich SPI gels, offering a promising alternative to traditional soy gels in the food industry.

Enhancing the gel properties of soy protein isolate: the role of oxidized konjac glucomannan in acid-induced gelation

BACKGROUND

Soy protein isolate (SPI) gels formed using a single coagulant often have poor water-holding capacity (WHC) and low hardness, making them fragile and unsuitable for transportation and storage. Adding compound coagulants or polysaccharides can improve the gelation properties of SPI gels induced by gluconolactone (GDL). This study explores the impact of oxidized konjac glucomannan (OKGM) on the physicochemical and structural properties of GDL-induced SPI gels, with the aim of evaluating the potential of OKGM for enhancing the overall quality and stability of these gels.

RESULTS

In this study, the composite gels demonstrated a significant increase in whiteness (69.02% to 70.59%) compared with the SPI gel (67.41%). Key physicochemical properties, such as water-holding capacity (WHC), textural characteristics, viscoelasticity, and thermal stability, were notably improved. Scanning electron microscopy (SEM) revealed a reduction in the average pore diameter of the composite gels from 70.57 ± 4.13 μm to 37.19 ± 0.24 μm when the oxidation degree of OKGM was kept at or below 60 min, contributing to a more compact and orderly microstructure. Enhanced hydrophobic and electrostatic interactions within the composite gels also accelerated the gelation process, shortening the gelation time from 15.77 ± 0.37 min to 12.45 ± 0.18 min.

CONCLUSION

The results demonstrate that OKGM acts effectively as a gel enhancer, improving the physicochemical and structural properties of SPI gels significantly. © 2024 Society of Chemical Industry.

Ultrasound-assisted fermentation effectively alleviates the weakening of wheat gluten network caused by long-chain inulin and the underlying mechanism

The main objective of the article is to elucidate the effects of ultrasonic treatment with different ultrasonic power (0 W, 200 W, 250 W, 300 W, 400 W and 500 W) on the rheology, water distribution, sulfhydryl disulfide bond content, microstructure, and gluten properties of FXL (Long-chain inulin) dough. When the ultrasonic power is 300 W, the protein polymerization can be promoted, thus improving the gluten network. The mechanical action and cavitation induced by ultrasound changed the water distribution of FXL dough and promoted the transition from weakly bound water to tightly bound water. The T21 value (tightly bound water relaxation time) was shortened from 0.25 to 0.16 and the A21 (tightly bound water content) was reduced from 6.35 to 5.18, an improvement of 22.6 %, at a power of 300 W. Ultrasound decreased the enthalpy of FXL dough, and increased the particle size and potential of gluten protein. The introduction of ultrasound increased the content of β-sheets structure (40.85) at 250 W. The microstructure of the FXL dough revealed that ultrasonic treatment induced a continuous tight membrane-like gluten network, while the application of 500 W ultrasonic power resulted in the exposure and depression of starch particles.

The structure and digestibility of sequential enzyme modified starch from Coix lachryma-jobi L

Sequential enzyme modification is a new method of starch modification. In this study, sequential enzyme (α-amylase (AA), β-amylase (BA), transglucosidase (TG) and pullulanase (Pull)) modification method was used to modify Coix lachryma-jobi L. starch, and the effects of TG treatment time on the physicochemical properties of starch were investigated. The results indicate that the morphology of sequentially enzyme-modified starch granules was altered, showing fissures, indentations on the granule surface, hollow regions, or fragmented structures. Compared with native starch, the amylose content, solubility, expansion potential and transparency increased, the relative crystallinity of Pull-S and TG-0 h starch decreased. With the extension of TG modification time, the relative crystallinity of starch granules, slow-digestible starch (SDS) content and peak gelatinization temperature (Tp) first increased and then decreased, while resistant starch (RS) first decreased and then increased. TG 12 h, RS content (40.65 %) was the lowest and SDS content (55.93 %) was the highest. Despite these changes, the difference in chain length distribution between native starch and enzyme-modified starch was comparable.

Exploring the influence of lysine incorporation on the physicochemical properties of quinoa protein gels formed under microwave versus conventional heating conditions

Quinoa protein (QP) has emerged as a promising alternative to gluten-based proteins in food applications due to its nutritional value and gluten-free nature. This study aimed to investigate the effect of microwave (MW) combined lysine (Lys) on the dielectric and gel properties. With increasing Lys concentrations, the dielectric constant initially declined then rose, while dielectric loss showed an inverse pattern. MW processed samples exhibited deeper penetration than water bath (WB), with penetration depth initially dipping then rising with amino acid levels. The combo treatment enhanced electromagnetic wave absorption and optimized absorber thickness. Optimal gel thickness for MW heating was approximately 1 cm, ensuring uniform radiation penetration, high absorption, and efficient energy conversion. Infrared analysis showed reduced α-helix/β-sheet and increased β-turn/random coil structures. The red shift and fluorescence intensity indicated Lys-induced partial unfolding QP. Notably, 0.6 % Lys with MW maximized gel hardness, adhesiveness, chewiness, elasticity, and viscoelastic properties (G', G"), significantly improving texture and rheology. The results provided a promising approach for the development of high-quality and gluten-free quinoa-based products.

Comparison of the effects of pectin with different esterification degrees on the thermal aggregation of wheat glutenin and gliadin

Our previous study found that pectin with different degrees of esterification (DE) could affect the thermal aggregation of gluten, but the mechanism was not clear. Analyzing the thermal aggregation of glutenin and gliadin supplemented with pectin can clarify this mechanism. With the increase of temperature, the particle size, disulfide bonds and β-sheet of glutenins increased, the surface hydrophobicity (H0) and fluorescence intensity decreased, and the network gradually aggregated, but the change trend of gliadins was opposite. These results suggested that the thermal aggregation of gluten mainly depended on glutenin. Glutenin and gliadin supplemented with low ester pectin (LEP) were in an aggregated state. At 95 °C, LEP (DE = 37 %) increased the particle size of glutenin and gliadin (141.83 μm and 19.91 μm), promoted the conversion of thiol to disulfide bonds, increased β-sheet (34.01 % and 31.13 %), decreased fluorescence intensity (2186.33 and 5165.33) and H0 (49.65 and 369.26). Scanning electron microscope (SEM) indicated that glutenin and gliadin supplemented with LEP retained a dense network structure, especially glutenin. This study elucidated the specific mechanism of how pectin affected the thermal aggregation of gluten. These results provide a more comprehensive theoretical support and scientific basis for understanding how pectin regulates the final quality of gluten-based products.

Ultrasonic treatment of emulsion gels with different soy protein-hemp protein composite ratios: Changes in structural and physicochemical properties

To improve the emulsion gel system of single soybean isolate protein (SPI) and to broaden the application field of hemp protein isolate (HPI), ultrasonic treatment and HPI were introduced to improve the properties of SPI emulsion gel and to explore the mechanism. The results showed that the gel strength (218.6 g) and water-holding capacity (86.24 %) of the emulsion gels were improved under ultrasonic treatments when the ratio of SPI:HPI was >6:4, and the reticulation structure of the gels was enhanced. When the ratio of SPI:HPI was <6:4, the gel structure was loose and formless. Ultrasonic treatment has a significant effect on the emulsion gel with the ratio of SPI:HPI was >6:4. Appropriate ultrasonic treatment (400 W) changed the protein structure, improved the rheological properties of emulsion gels to form the protein-oil-coated network structure. However, excessive ultrasonic treatment (600 W) will destroy the conformation of the protein, reducing the stability of the structure. The effect of ultrasonic treatment on emulsion gels with the ratio of SPI:HPI was <6:4 is low, but improved the gel protein digestibility. This study provides a theoretical basis for the application of ultrasonic in composite protein emulsion gels systems and the development and application of HPI.

Unveiling the structural and physico-chemical properties of glutenin macropolymer under frozen storage: Studies on experiments and molecular dynamics simulation

Glutenin macropolymer (GMP) plays an important role in wheat gluten fractions, and extensively presents in the frozen dough. However, the effects of freezing treatment on GMP remain not abundantly understood. In this study, we investigated the structure and physico-chemical properties of GMP under frozen storage through experimental methods and bioinformatics algorithms. Results revealed that freezing treatment weakened the structure and properties of GMP to varying degrees, and GMP might have tolerance to short-term freezing storage. During frozen storage, portions of α-helix in GMP were converted into β-turn and random coil, slight changes in the tertiary structure, and its surface hydrophobicity increased by 4.8 %. SDS-PAGE profiles indicated that the depolymerization behavior mainly occurred above the Mw of 70.0 kDa. Slight changes were observed in the content of free thiol groups and disulfide bonds during frozen storage. Combination of fluorescence spectroscopy and intermolecular interactions suggested that hydrogen bonds and hydrophobic interactions were probably important indicators for evaluating the deterioration of GMP. Frozen storage resulted in an unfolded and open protein network. Moreover, freezing treatment led to a main conversion from strongly bond water to weakly bond water. However, no significant changes in water distribution were observed during the first 7 days of frozen storage. The viscoelastic loss of GMP primarily occurred in the first fourteen days, but tan δ did not significantly increased, indicating that protein has not been seriously deteriorated. Molecular dynamics simulation further supplemented and validated these experimental results from molecular level through analysis of root mean square deviation, root mean square fluctuation, solvent-accessible surface area, radius of gyration and the number of hydrogen bonds.

Effects of purple cabbage anthocyanin extract on the gluten characteristics and the gluten network evolution of high-gluten dough

BACKGROUND

Anthocyanins are polyphenolic pigments that have hypoglycemic, antioxidation, anti-aging, and other effects. Research has shown that polyphenols can optimize the processing of dough and improve the texture and nutritional characteristics of dough products. The formation of gluten networks is decisive for the quality of flour products. The effects of purple cabbage anthocyanin (PCA) extract on the structure, microscopic morphology, and network formation of gluten protein were studied, and the types of cross-linking between PCA and gluten protein are discussed.

RESULTS

The results show that PCA extract increased the free sulfhydryl (SH) group content and the free amino group of gluten proteins, stimulated an increase in the β-sheet ratio and the decrease of α-helix ratio, and increased the gluten index significantly (P < 0.05). The PCA extract also induced gluten protein aggregation, increased the height of protein molecular chains, and stimulated the formation of gluten networks. When PCA extract concentrations were 4 g kg-1 and 8 g kg-1, the gluten network was more homogeneous, continuous, and dense.

CONCLUSION

Appropriate anthocyanins have a positive effect on the properties of gluten and promote the formation of gluten networks. Excessive anthocyanins destroy gluten protein interaction and harm gluten cross-linking. This study may provide a useful source of data for the production of functional flour products rich in anthocyanins. © 2024 Society of Chemical Industry.

Effects of konjac glucomannan with different degrees of deacetylation on the properties and structure of wheat gluten protein

The properties and structure of gluten protein with different deacetylation degrees of konjac glucomannan (KGM) were investigated, in an attempt to improve the quality of gluten protein in flour products. Results showed that deacetylated KGM (DKGM) could improve the textural properties and enhance the thermal stability of gluten protein. DKGM increased the water holding capacity and shortened the T2 relaxation time of gluten after removing some acetyl groups. As the deacetylation degree increased, the hardness and adhesiveness of gluten gels gradually increased, while the springiness decreased. In addition, the presence of DKGM promoted the conversion from free sulfhydryl to disulfide bonds and increased the β-sheet content in gluten protein. The low-deacetylation KGM decreased the surface hydrophobicity and fluorescence intensity of gluten protein, and the microstructures of gluten gels became more compact. Compared with gluten protein-KGM complex gel, the degradation temperature of gluten protein-DKGM complex gels was observed to increase by >3 °C. Overall, the low-deacetylation KGM was beneficial for improving the physicochemical properties and maintaining the network structure of gluten protein. This study provides valuable references and practical insights to improve gluten quality in the flour industry.

Effect of sanxan as novel natural gel modifier on the physicochemical and structural properties of microbial transglutaminase-induced mung bean protein isolate gels

Mung bean protein isolate (MBPI) has attracted much attention as an emerging plant protein. However, its application was limited by the poor gelling characteristics. Thus, the effect of sanxan (SAN) on the gelling behavior of MBPI under microbial transglutaminase (MTG)-induced condition were explored in this study. The results demonstrated that SAN remarkably enhanced the storage modulus, water-holding capacity and mechanical strength. Furthermore, SAN changed the microstructure of MBPI gels to become more dense and ordered. The results of zeta potential indicated the electrostatic interactions existed between SAN and MBPI. The incorporation of SAN altered the secondary structure and molecular conformation of MBPI, and hydrophobic interactions and hydrogen bonding were necessary to maintain the network structure. Additionally, in vitro digestion simulation results exhibited that SAN remarkably improved the capability of MBPI gels to deliver bioactive substances. These findings provided a practical strategy to use natural SAN to improve legume protein gels.

Rheological, thermal, and structural properties of heat-induced gluten gel: Effects of starch with varying degrees of debranching

This study evaluated the effects of starch with varying degree of debranching on the rheological, thermal, and structural properties of heat-induced gluten gel. As the duration of starch debranching treatment increased from 0 to 8 h, the viscoelasticity of the gel containing debranched starch (DBS) improved. Compared with the gluten gel (G), the gel strength of the G + DBS (8 h) sample increased by 65.2 %. The degradation temperature of gluten was minimally affected by DBS, while the weight loss rate increased by 4.4 %. Furthermore, the α-helical structure of gluten decreased, concomitant with an increase in β-sheet content. Notably, DBS treated for 8 h exhibited more hydrogen bonds with the tyrosine of gluten and triggered disulfide bridge conformation to transition from g-g-g to t-g-g, thereby reducing the stability of the molecular conformation of gluten proteins, as evidenced by the decreased height and width of the molecular chains observed in atomic force microscopy images. Overall, the composite gel structure induced by DBS exhibited a more continuous and homogeneous owing to the improved compatibility between DBS and gluten proteins, favoring the formation of a robust gel. These findings provide valuable insights for utilizing DBS to enhance gluten gel properties.

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.

Influence of dextrans on the textural, rheological, and microstructural properties of acid-induced faba bean protein gels

Dextrans (DXs) are a group of natural polysaccharides with different branching patterns. Previous studies examining the effects of DXs on plant protein gels have only focused on α-(1 → 3)-branched DXs. Here, we compared the effects of α-(1 → 3)-branched DX L12 with those of two α-(1 → 2)-branched DXs on the properties of glucono-δ-lactone-induced faba bean protein isolate (FPI) gels. DX L12 showed stronger effects in decreasing gel hardness and enhancing gel viscoelasticity than the other two DXs. Moreover, DX L12 decreased the water-holding capacity of FPI gels, whereas the other DXs enhanced it. Microstructural analysis revealed that DX addition promoted phase separation during gel formation. However, FPI/L12 gels exhibited greater phase separation than the other two gels and contained larger void spaces. These differences could be attributed to the varying water adsorption and self-association properties of the DXs. These findings could guide the application of DX in the tailored preparation of plant protein gels.

Effects of nitrogen fertilizer on the physicochemical, structural, functional, thermal, and rheological properties of mung bean (Vigna radiata) protein

Nitrogen fertilizer can affect the seed quality of mung bean. However, the effects of nitrogen fertilizer on the properties of mung bean protein (MBP) remain unclear. We investigated the effects of four nitrogen fertilization levels on the physicochemical, structural, functional, thermal, and rheological properties of MBP. The results showed that the amino acid and protein contents of mung bean flour were maximized under 90 kg ha-1 of applied nitrogen treatment. Nitrogen fertilization can alter the secondary and tertiary structure of MBP. The main manifestations are an increase in the proportion of β-sheet, the exposure of more chromophores and hydrophobic groups, and the formation of loose porous aggregates. These changes improved the solubility, oil absorption capacity, emulsion activity, and foaming stability of MBP. Meanwhile, Thermodynamic and rheological analyses showed that the thermal stability, apparent viscosity, and gel elasticity of MBP were all increased under nitrogen fertilizer treatment. Correlation analysis showed that protein properties are closely related to changes in structure. In conclusion, nitrogen fertilization can improve the protein properties of MBP by modulating the structure of protein molecules. This study provides a theoretical basis for the optimization of mung bean cultivation and the further development of high-quality mung bean protein foods.

Influence of starch-protein interactions on the digestibility and chemical properties of a 3D-printed food matrix based on salmon by-product proteins

This study evaluated the influence of starch-protein interactions on the chemical properties and digestibility of a 3D-printed gel based on salmon by-product protein. Changes in the starch-protein interactions of the stable cornstarch (CS, 15%) and salmon protein isolate (SPI, 4%-12%) printable gels during the in vitro gastrointestinal digestion process were studied by principal component analysis. Protein-rich printed gels increased resistant starch content by 18.05%. Changes in chemical properties and the starch-protein concentration of the gels during the digestion process were highly correlated. The CS-SPI gels in the gastric and intestinal phases exhibited lower α-helix/β-sheet ratio and fluorescence intensity values, whereas surface hydrophobicity increased. This resulted in more ordered structures with a high level of molecular interaction that inhibited enzymatic hydrolysis. This study provides crucial information about the transformations of starch-protein interactions during the digestibility of 3D-printed food matrices as an alternative source of nutrients with a high nutritional quality.

Noncovalent Conjugates of Anthocyanins to Wheat Gluten: Unraveling Their Microstructure and Physicochemical Properties

Intake of polyphenol-modified wheat products has the potential to reduce the incidence of chronic diseases. In order to determine the modification effect of polyphenols on wheat gluten protein, the effects of grape skin anthocyanin extract (GSAE, additional amounts of 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%, respectively) on the microstructure and physicochemical properties of gluten protein were investigated. The introduction of GSAE improves the maintenance of the gluten network and increases viscoelasticity, as evidenced by rheological and creep recovery tests. The tensile properties of gluten protein were at their peak when the GSAE level was 0.3%. The addition of 0.5% GSAE may raise the denaturation temperature of gluten protein by 6.48 °C-9.02 °C at different heating temperatures, considerably improving its thermal stability. Furthermore, GSAE enhanced the intermolecular hydrogen bond of gluten protein and promoted the conversion of free sulfhydryl groups to disulfide bonds. Meanwhile, the GSAE treatment may also lead to protein aggregation, and the average pore size of gluten samples decreased significantly and the structure became denser, indicating that GSAE improved the stability of the gluten spatial network. The positive effects of GSAE on gluten protein properties suggest the potential of GSAE as a quality enhancer for wheat products.

Effects of chia seed gum on the physicochemical properties of frozen dough and the quality of dumplings

This study was designed to investigate the properties of chia seed gum (CSG) and its use in frozen dough. The CSG prepared by vacuum freeze-drying had the lowest water separation (4.22 ± 0.11 %) after three freeze-thaw cycles and the best color among the samples. The addition of 0.4 % to 1.0 % CSG significantly increased the peak, trough and final viscosity and decreased the breakdown and setback of the flour. The water absorption and cooking stability of the dough increased with increasing CSG content. The addition of 0.8 %-1.0 % CSG significantly increased the content of strongly bound water in dough during frozen storage. The CSG improved the texture of dough, and there were no significant differences in hardness, springiness, cohesiveness or chewiness of dough with 0.8 %-1.0 % CSG during frozen storage for 30 days. The cooking loss rate and the cracking rate of the dumpling wrappers with 0.8 % CSG were reduced by 2.31 % and 21.34 %, respectively. In conclusion, CSG can be used to improve the quality of wheat dough and its products and has promising applications in flour products.

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.

Effects of Dextran on the Gel Properties of Faba Bean Protein Isolates Prepared Using Different Processes

The properties of faba bean (Vicia faba L.) protein isolate (FPI) gels depend on their starting protein material and can be modulated by the addition of polysaccharides. In order to investigate the interplay between these two factors, commercial FPI (FPI1) and FPI prepared in-house (FPI2) were used to fabricate glucono-delta-lactone-induced gels, with or without dextran (DX) addition. FPI1 exhibited lower solubility in water and a larger mean particle size, likely because it experienced extensive degradation due to the intense conditions involved in its preparation. The FPI1 gel showed a similar water-holding capacity as the FPI2 gel; however, its hardness was lower and viscoelasticity was higher. After DX addition, the hardness of both FPI gels decreased, while their water-holding capacity increased. Interestingly, DX addition decreased the viscoelasticity of the FPI1 gel but enhanced the viscoelasticity of the FPI2 gel. The microstructural analysis demonstrated that the density of the aggregation network decreased in the FPI1 gel after DX addition but increased in the FPI2 gel. This was consistent with the changes observed in the dominant protein interaction forces in these gels after DX addition. Overall, these findings have the potential to guide ingredient selection for the tailored preparation of FPI gels.

Effect of Na+ and Ca2+ on the texture, structure and microstructure of composite protein gel of mung bean protein and wheat gluten

To investigate the change of ionic strength on the gel characteristics during the processing of mung bean protein-based foods, the effects of NaCl and CaCl2 at different concentrations (0-0.005 g/mL) on the properties of mung bean protein (MBP) and wheat gluten (WG) composite protein gel were studied. The results showed that low concentration (0.001-0.002 g/mL) could significantly improve the water holding capacity (WHC), storage modulus (G') and texture properties of composite protein gel (MBP/WG), while the surface hydrophobicity (H0) and solubility were significantly decreased (P < 0.05). With the increase of ion concentration, the secondary structures of MBP/WG shifted from α-helix to β-sheet, and the fluorescence spectra also showed fluorescence quenching phenomenon. By analyzing the intermolecular forces of MBP/WG, it was found that with the addition of salt ions, the hydrogen bonds was weakened and the electrostatic interactions, hydrophobic interactions and disulfide bonds were enhanced, which in turn the aggregation behavior of MBP/WG composite protein gel was affected and larger aggregates between the proteins were formed. It could be also demonstrated that the gel network was denser due to the addition of these large aggregates, thus the gel properties of MBP/WG was improved. However, too many salt ions could disrupt the stable network structure of protein gel. This study can provide theoretical support to expand the development of new mung bean protein products.

Preparation and Characterization of Gluten/SDS/Chitosan Composite Hydrogel Based on Hydrophobic and Electrostatic Interactions

Gluten is a natural byproduct derived from wheat starch, possessing ideal biocompatibility. However, its poor mechanical properties and heterogeneous structure are not suitable for cell adhesion in biomedical applications. To resolve the issues, we prepare novel gluten (G)/sodium lauryl sulfate (SDS)/chitosan (CS) composite hydrogels by electrostatic and hydrophobic interactions. Specifically, gluten is modified by SDS to give it a negatively charged surface, and then it conjugates with positively charged chitosan to form the hydrogel. In addition, the composite formative process, surface morphology, secondary network structure, rheological property, thermal stability, and cytotoxicity are investigated. Moreover, this work demonstrates that the change can occur in surface hydrophobicity caused by the pH-eading influence of hydrogen bonds and polypeptide chains. Meanwhile, the reversible non-covalent bonding in the networks is beneficial to improving the stability of the hydrogels, which shows a prominent prospect in biomedical engineering.

Interactions of soy protein isolate with common and waxy corn starches and their effects on acid-induced cold gelation properties of complexes

Soy protein isolate (SPI) was mixed with different concentrations of common starch (CS) and waxy starch (WS) from corn. The interactions of SPI with CS or WS and their effects on the acid-induced cold gelation properties of complexes were investigated. Compared with WS, SPI could bind to CS more strongly and formed a tighter SPI-CS non-covalent complex, which resulted in the increased β-sheet and a more ordered secondary structure. The gel strength, water holding capacity (WHC), viscoelasticity, hydrophobic interactions and thermal stability of SPI-CS complex gels were enhanced as increasing CS concentration, and the complex with 2% of CS had the best gelation properties. Although adding WS reduced the gel strength, rheological properties and hydrophobic interactions of SPI-WS complex gels, it improved the WHC and thermal stability of the complex gels. Therefore, CS had a broader effect on improving acid-induced cold gelation properties of SPI than WS.

Effect of konjac glucomannan on aggregation patterns and structure of wheat gluten with different strengths

Konjac glucomannan (KGM) can act as a food additive to improve the quality of dough. The effects of KGM on the aggregation patterns and structural properties of weak, middle, and strong gluten were studied. We found that with a higher proportion of KGM substitution (10%), the aggregation energy of middle and strong gluten became lower than the control samples, while exceeding the control for weak gluten. With 10% KGM, aggregation of glutenin macropolymer (GMP) was enhanced for weak gluten, but suppressed for middle and strong gluten. The α-helix transferred to β-sheet in weak, but caused more random-coil structures for middle and strong gluten induced by 10% KGM. With 10% KGM, the network for weak gluten became more continuous, but severely disrupted for middle and strong gluten. Thus, KGM has distinct effects on weak, middle, and strong gluten, which related to the alteration of gluten secondary structures and GMP aggregation pattern.

Effect of multiple-frequency ultrasound-assisted transglutaminase dual modification on the structural, functional characteristics and application of Qingke protein

Qingke protein rich in restricted amino acids such as lysine, while the uncoordination of ratio of glutenin and gliadin in Qingke protein has a negative impact on its processing properties. In this study, the effect of multiple-frequency ultrasound combined with transglutaminase treatment on the functional and structural properties of Qingke protein and its application in noodle manufacture were investigated. The results showed that compared with the control, ultrasound-assisted transglutaminase dual modification significantly increased the water and oil holding capacity, apparent viscosity, foaming ability, and emulsifying activity index of Qingke protein, which exhibited a higher storage modulus G' (P < 0.05). Meanwhile, ultrasound combined with transglutaminase treatment enhanced the cross-linking degree of Qingke protein (P < 0.05), as shown by decreased free amino group and free sulfhydryl group contents, and increased disulfide bond content. Moreover, after the ultrasound-assisted transglutaminase dual modification treatment, the fluorescence intensity, the contents of α-helix and random coil in the secondary structure of Qingke protein significantly decreased, while the β-sheet content increased (P < 0.05) compared with control. SDS-PAGE results showed that the bands of Qingke protein treated by ultrasound combined with transglutaminase became unclear. Furthermore, the quality of Qingke noodles made with Qingke powder (140 g/kg dual modified Qingke protein mixed with 860 g/kg extracted Qingke starch) and wheat gluten 60-70 g/kg was similar to that of wheat noodles. In summary, multiple-frequency ultrasound combined with transglutaminase dual modification can significantly improve the physicochemical properties of Qingke protein and the modified Qingke proteins can be used as novel ingredients for Qingke noodles.

Consolidating the gelling performance of myofibrillar protein using a novel OSA-modified-starch-stabilized Pickering emulsion filler: Effect of starches with distinct crystalline types

Starch-stabilized Pickering emulsions were employed as a novel particulate filler in myofibrillar protein (MP)-based gels for improving the gelling characteristics. The role of emulsions prepared by native starches (NS) with distinctive crystalline types (i.e., A-type waxy corn starch, B-type potato starch, and C-type pea starch) and their OSA-modified counterparts (A-OS, B-OS, C-OS) in the gelling performance was evaluated and compared with MP-stabilized-emulsion. Compared with MP-emulsion, starch-emulsion caused substantial increases in the gelling properties, notably for OSA-starch emulsions. Herein, A-OS exhibited up to 1.26-, 5.3-, and 2.9-fold increments in storage modulus, gel strength, and water holding capacity relative to pure MP gel, respectively, higher than B-OS and C-OS. Moreover, light microscopy evinced a more compact gel network filled with smaller and uniform oil droplets when A-OS emulsions were incorporated into the gels. The addition of OSA-starch emulsions, especially A-OS emulsion, facilitated the protein conformational conversion from α-helix to β-sheet and caused a marked reduction of free sulfhydryls in the gels; yet, the chemical forces that stabilized the gels altered, where remarkable reinforcements in hydrogen bond and hydrophobic interaction were detected, in support of the construction of splendid MP gels. Hence, OSA-starch emulsions show promise as functional components in meat products.

Characterization of sonicated gluten protein and subsequent rheological properties of model dough and noodles

BACKGROUND

The present study aimed to investigate the effects of the thermo-mechanical and rheological properties of a wheat gluten-sonicated model dough and noodles, as well as the effects of ultrasonic frequency (20, 28, 40, 68 and 80 kHz) on the functional properties and structural features of gluten.

RESULTS

Water absorption, stability and developmental time, and viscoelastic behavior of gluten-sonicated model dough were all found to be improved. Water absorption, tensile resistance and stretching distance of noodles increased markedly, whereas cooking loss decreased. Ultrasonication at different frequencies also significantly affected gluten structure, including its surface hydrophobicity, micro-network structure, and secondary and tertiary structures. These alterations then caused changes in its functional characteristics. Compared to untreated gluten, sonicated gluten exhibited significantly increased oil and water capacities (8.75-15.26% and 100.65-127.71% higher than the untreated gluten, respectively), foaming and emulsifying properties, and increased solubility (63.46-98.83% higher than control). In addition, these findings indicated that 40 kHz was the likely resonance frequency of the cavitation bubble in the gluten solution. However, sodium dodecyl sulfate-polyacrylamide gel electrophoresis electropherograms revealed that such treatments did not affect the molecular weight of gluten, which was also consistent with its unchanged disulfide bond content.

CONCLUSION

The present study clarified the impact of frequency on the properties of gluten and model dough. The best frequency for modification of gluten was 40 kHz. Collectively, these findings suggest that ultrasonic technology has the potential for use in modifying wheat gluten and commercial noodle processing. © 2022 Society of Chemical Industry.

Development of high-internal-phase emulsions stabilized by soy protein isolate-dextran complex for the delivery of quercetin

BACKGROUND

Protein-polysaccharide complexes have been widely used to stabilize high-internal-phase emulsion (HIPEs). However, it is still unknown whether soy protein isolate-dextran (SPI-Dex) complexes can stabilize HIPEs or what is the effect of Dex concentration on the HIPEs. Furthermore, the non-covalent interaction mechanism between SPI and Dex is also unclear. Therefore, we fabricated SPI-Dex complexes and used them to stabilize HIPEs-loaded quercetin and explore the interaction mechanism between SPI and Dex, as well as the effect of Dex concentration on the particle size, ζ-potential, microstructure, rheology, quercetin encapsulation efficiency, and gastrointestinal fate of the HIPEs.

RESULTS

Spectral analysis (fourier transform infrared spectroscopy, ultraviolet spectroscopy, and fluorescence spectroscopy) results identified the formation of SPI-Dex complexes, and indicated that the addition of Dex changed the spatial structure of SPI, whereas thermodynamic analysis (ΔH > 0, ΔS > 0) showed that hydrophobic interactions were the main driving forces in the formation of SPI-Dex complexes. Compared with HIPEs stabilized by SPI, the SPI-Dex complex-stabilized HIPEs had smaller particles (3000.33 ± 201.22 nm), as well as higher ζ-potential (-21.73 ± 1.10 mV), apparent viscosities, modulus, and quercetin encapsulation efficiency (98.19 ± 0.14%). In addition, in vitro digestion revealed that SPI-Dex complex-stabilized HIPEs significantly reduced the release of free fatty acid and improved quercetin bioaccessibility.

CONCLUSION

HIPEs stabilized by SPI-Dex complexes delayed the release of free fat acid and improved the bioaccessibility of quercetin, and may be help in designing delivery systems for bioactive substances with specific properties. © 2022 Society of Chemical Industry.

Effects of Different Gluten Proteins on Starch’s Structural and Physicochemical Properties during Heating and Their Molecular Interactions

Starch–gluten interactions are affected by biopolymer type and processing. However, the differentiation mechanisms for gluten–starch interactions during heating have not been illuminated. The effects of glutens from two different wheat flours (a weak-gluten (Yangmai 22, Y22) and a medium-strong gluten (Yangmai 16, Y16)) on starch’s (S) structural and physicochemical properties during heating and their molecular interactions were investigated in this study. The results showed that gluten hindered the gelatinization and swelling of starch during heating when temperature was below 75 °C, due to competitive hydration and physical barriers of glutens, especially in Y22. Thus, over-heating caused the long-range molecular order and amylopectin branches of starch to be better preserved in the Y22-starch mixture (Y22-S) than in the Y16-starch mixture (Y16-S). Meanwhile, the starch’s degradation pattern during heating in turn influenced the polymerization of both glutens. During heating, residual amylopectin branching points restricted the aggregation and cross-linking of gluten proteins due to steric hindrance. More intense interaction between Y16 and starch during heating mitigated the steric hindrance in starch–gluten networks, which was due to more residual short-range ordered starch and hydrogen bonds involved in the formation of starch–gluten networks in Y16-S during heating.

The Influence of Water-Unextractable Arabinoxylan and Its Hydrolysates on the Aggregation and Structure of Gluten Proteins

This study aimed to investigate the influence of water-unextractable arabinoxylan (WUAX) and its hydrolysates on the aggregation and structure of gluten proteins and reveal the underlying mechanism. In this work, the WUAX was treated with enzymatic hydrolysis and the changes of their molecular weights and structures were analyzed. Meanwhile, the conformation and aggregation of gluten were determined by reversed-phase HPLC, FT-Raman spectroscopy, and confocal laser scanning microscopy. The results showed that the extra WUAX could impair the formation of high Mw glutenin subunits, and the enzymatic hydrolysis arabinoxylan (EAX) could induce the aggregation of gluten subunits. And, the gluten microstructure was destroyed by WUAX and improved by EAX. Besides, the interactions of WUAX and EAX with gluten molecules were different. In summary, these results indicated that enzymatic hydrolysis changed the physicochemical properties of arabinoxylan and affected the interaction between arabinoxylan and gluten proteins.

Gluten-starch interface characteristics and wheat dough rheology-Insights from hybrid artificial systems

Referring to the total surface existing in wheat dough, gluten-starch interfaces are a major component. However, their impact on dough rheology is largely unclear. Common viewpoints, based on starch surface modifications or reconstitution experiments, failed to show unambiguous relations of interface characteristics and dough rheology. Observing hybrid artificial dough systems with defined particle surface functionalization gives a new perspective. Since surface functionalization standardizes particle-polymer interfaces, the impact on rheology becomes clearly transferable and thus, contributes to a better understanding of gluten-starch interfaces. Based on this perspective, the effect of particle/starch surface functionality is discussed in relation to the rheological properties of natural wheat dough and modified gluten-starch systems. A competitive relation of starch and gluten for intermolecular interactions with the network-forming polymer becomes apparent during network development by adsorption phenomena. This gluten-starch adhesiveness delays the beginning of non-linearity under large deformations, thus contributing to a high deformability of dough. Consequently, starch surface functionality affects the mechanical properties, starting from network formation and ending with the thermal fixation of structure.

Effect of simultaneous treatment combining ultrasonication and rutin on gliadin in the formation of nanoparticles

Proteins, one of the vital nutritional compounds sensitive to the environment, can be modified by interaction with polyphenols. Ultrasonication has been applied for enhancing the functional properties of proteins. In this study, the interactions of gliadin (G) and rutin (R) in the absence and presence of ultrasonication (0, 150, 300, 450, and 600 W) for 20 min were investigated, with a focus on the properties of emulsions prepared by G-R complexes. Ultrasonication improved the interaction, which increased the content of β-type secondary structure. Ultrasonication at 450 W increased the particle size of the conjugates. For Pickering emulsions, treating the covering of R on G with ultrasonication improves the stability of the G-based emulsion significantly, owing to the strong films formed on the oil-water interfaces. The G-R complexes treated at 450 W ultrasonication formed emulsions that showed higher potential and storage modulus (G') and denser microstructures than those of the untreated emulsions. Nevertheless, ultrasound treatment at 600 W weakened the emulsion properties that were stabilized by the conjugates. Ultrasound combined R was shown to be a potential processing technology for changing the protein structure and producing stable emulsions. PRACTICAL APPLICATION: The interactions between proteins and polyphenols are able to preserve the stability of the functional compounds, allow targeted and controlled release, and improve the texture of these complexes employed in the food industry. Improvements in the functional characteristics of the protein-polyphenol complexes so that they possess high emulsifying stability during food processing is a crucial factor for employing them in the food industry. Therefore, the aim of this research is using a soluble complex of gliadin-rutin for the development of its functional characteristics.

Moisture Distribution and Structural Properties of Frozen Cooked Noodles with NaCl and Kansui

The effects of NaCl (1-3%) and kansui (0.5-1.5%) on the quality of frozen cooked noodles (FCNs) were investigated, which provided a reference for alleviating the quality deterioration of FCNs. Textural testing illustrated that the optimal tensile properties were observed in 2% NaCl (N-2) and the maximum hardness and chewiness were reached at 1% kansui (K-1). Compared to NaCl, the water absorption and cooking loss of recooked FCNs increased significantly with increasing kansui levels (p < 0.05). Rheological results confirmed NaCl and kansui improved the resistance to deformation and recovery ability of thawed dough; K-1 especially had the highest dough strength. SEM showed N-2 induced a more elongated fibrous protein network that contributed to the extensibility, while excessive levels of kansui formed a deformed membrane-like gluten network that increased the solid loss. Moisture analysis revealed that N-2 reduced the free water content, while K-1 had the lowest freezable water content and highest binding capacity for deeply adsorbed water. The N-2 and K-1 induced more ordered protein secondary structures with stronger intermolecular disulfide bonds, which were maximally improved in K-1. This study provides more comprehensive theories for the strengthening effect of NaCl and kansui on FCNs quality.