Self-supporting Gels Research Articles

Impact of Five Soy Proteins on Lean Chicken Breast Systems with Varying Moisture Contents: Cooking Loss, Texture, Microstructure, and T2 NMR

With increasing global meat consumption, meat–plant hybrid products have gained interest as a sustainable alternative. Soy proteins have been used in small quantities (2–3%) as meat extenders, yet limited data exist on their use at higher levels. Here, five commercial soy proteins (four isolates: SPI-A to -D; one concentrate: SPC) were used for meat replacement in lean meat batters with 0/40/80% added water. Cooking loss, texture, light micrographs, and T2 relaxation were analyzed. At 33% and 66% meat replacement, soy protein treatments maintained comparable or reduced cooking loss; SPI-D and SPC were the least and most effective, respectively. Complete replacement eliminated cooking loss in 0% and 40% water systems but failed to form self-supporting gels in the 80% system. At 33% replacement, SPI-A to -C generally increased hardness, whereas increasing the replacement level further to 66% decreased it. In the 0% and 80% systems, SPI-A treatments exhibited hardness comparable to controls, SPI-D treatments drastically reduced hardness, and SPC treatments maintained greater hardness than the controls even at 66% replacement. Micrographs offered potential explanations for these macroscopic measurements. NMR T2 data indicated that soy proteins restricted water mobility both pre- and post-cooking. Specifically, in the 40% and 80% systems, the T22 peaks (expelled liquid) of the hybrid samples containing 33% SPI-A were ~350 ms and 760 ms, compared to ~570 ms and 1170 ms for the meat controls, respectively. In conclusion, most soy proteins (except SPI-D) enhanced water binding, with SPI-A showing optimal texture and SPC showing promise as a more economical alternative.

Mechanism on microbial transglutaminase and Tremella fuciformis polysaccharide-mediated modification of lactoferrin: Development of functional food

Lactoferrin (LF) with various biological functions demonstrates great application potential. However, its application was restricted by its poor gelation and instability. The aim of this work was to explore the effect of microbial transglutaminase (MTGase) and Tremella fuciformis polysaccharide (TP) on the functional properties of LF. The formation of a self-supporting LF gel could be induced by MTGase through generating covalent crosslinks between the LF protein molecules. Meanwhile, TP was introduced into the gel system to improve the strength of LF-TP composite gels by enhancing non-covalent interactions such as hydrogen bond and electrostatic interactions during gel formation. Additionally, the LF-TP composite gel exhibited outstanding functional characteristics such as gastrointestinal digestive stability and antioxidant property. This work clarified the mechanism on MTGase and TP-mediated modification of lactoferrin, offered a novel strategy to increase the functional characteristics of LF, and enlarged the application range of LF and TP.

Separation of ovomucin from duck egg white and its “acid-tight /alkali-loose” self-supporting gel properties under different pH

Ovomucin is a key component in maintaining the viscous nature of egg white and has vast potential in the utilization of food industry. The objectives of the study were to determine the effect of different pH on the extractability and gel properties of ovomucin. After removing lysozyme through ion exchange, the diluted duck egg white was acidified to a narrow pH range (4.50, 4.75, 5.00, 5.25, 5.50, 5.75 and 6.00) to precipitate ovomucin. By comprehensive study of purity, yield, and convenience of large-scale preparation, 4.75 was chosen as the optimal pH to extract ovomucin with the highest purity of 85.17 ± 2.31% and a compromised yield of 4.60 ± 0.06 mg/g duck egg white. A series of self-supporting gels were prepared with freeze-dried ovomucin powder at room temperature upon rehydration and centrifugation, and the gels properties were highly associated with pH. Gel formed around pH 5 was the aggregate of natural globular proteins with lowest hydrophobicity and electrostatic interaction, relatively dense structure and high water-holding capacity (WHC). Stronger acidic conditions disrupted the disulfide bonds and formed a rougher spherical aggregate. Under alkaline conditions, however, the protein gradually unfolded and broke into linear basic polypeptides, thus a porous three-dimensional network was formed. Overall, this study provided insights into the formation mechanism of the “acid-tight/alkali-loose” ovomucin gels, and introduced a potential candidate for the development of bioactive substance delivery materials.

3D printed emulsion based on arginine-myofibrillar protein

The feasibility of preparing high internal phase Pickering emulsions (HIPPEs) from arginine (Arg) and tilapia myofibrillar protein (MP) complex particles for 3D printing was investigated. The characterization of Arg-MP solutions showed that the Arg-MP complexes had excellent emulsification potential. HIPPE stabilized by Arg-MP had a strong self-supporting and stable gel structure. Therefore, HIPPE stabilized by Arg-MP showed excellent stability. Furthermore, the viscoelasticity and thixotropic recovery of the Arg-MP-stabilized HIPPEs increased with increasing Arg concentrations. This made them suitable for 3D printing. Notably, the Arg-MP stabilized HIPPEs exhibited the best printing precision shape, resolution, and clear contours in 3D printing at an Arg concentration of 0.5 wt%. Our results provide a valuable source of food-grade materials for 3D printing inks and demonstrate a promising strategy for deep processing of tilapia myofibrillar protein.

Synergistic effects of microbial transglutaminase and apple pectin on the gelation properties of pea protein isolate and its application to probiotic encapsulation

The low gelation capacity of pea protein isolate (PPI) limits their use in food industry. Therefore, microbial transglutaminase (MTG) and apple pectin (AP) were combined to modify PPI to enhance its gelling characteristics, and the mechanism of MTG-induced PPI-AP composite gel generation was investigated. PPI (10 wt%) could not form a gel at 40 °C, while MTG-treated PPI (10 wt%) formed a self-supporting gel at 40 °C. Subsequently, the addition of AP further promoted the crosslinking of PPI and significantly improved the water holding capacity, rheology, and strength of PPI gels, which was attributed to both hydrogen and isopeptide bonds in the composite gel. Additionally, the PPI-AP composite gel showed excellent protection ability, and the survival rate of probiotics could reach over 90%, which could be used as an effective delivery system. This study verified that MTG and AP were efficient in enhancing the functional quality of PPI gels.

Gelation behavior between Nicandra physalodes (Linn.) Gaertn. pectin and Ca2+ is governed by degree and pattern of methylesterification

Nicandra physalodes (Linn.) Gaertn. Pectin (NPGP) is a new type of natural low methoxy pectin (LMP), however, the relatively poor gelling capacity of NPGP and neutral calcium limits its applicability in the food industry. In this study, we improved the gelling capacity of NPGP, and the impact of the degree and pattern of methyl esterification on NPGP gelation behavior triggered by neutral calcium was investigated. To achieve this goal, NPGP was treated with pectin methyl esterase (PME, 30 °C, pH 4.5) for various time. This modification decreased the degree of methyl esterification (DM) and generated different patterns of methyl ester distribution, quantified as the degree of blockiness (DB). The obtained PME-NPGPs possess the ability to form self-supporting gels in the presence of CaCl2, with the highest gel hardness being 331.98 g. By estimating the DM and quantifying the DB of PME-NPGP, the DB value of PME-NPGP was increased from 17.74% to 31.84% with DM decreasing from 33.09% to 17.37%, indicating a shift toward a more blockwise distribution of nonmethylated GalA in NPGP. Additionally, adsorption isotherms for Ca2+ on de-esterified NPGP were determined, enabling the quantification of its cation binding capacity and interaction energy. Reducing DM and increasing DB of NPGP were found to enhance NPGP's binding capacity to Ca2+. This research provides an important foundation for NPGP food processing, and the obtained PME-NPGP can be promising in the fields of food gel and drug delivery.

Fabrication of telechelic DNA-bridged food emulsion gel as edible ink for 3D printing

Abstract Objectives Interdroplet interactions affect the properties and textures of emulsions. In this study, we creatively introduced telechelic DNA to link oil droplets directly at molecular scale to further improve the viscoelastic properties of emulsions. Materials and Methods A stable emulsion with 70% oil fraction was prepared by adding 40 mg/mL of whey protein isolate and peach gum polysaccharide complex (WPI–PGP complex). The addition of telechelic DNA (0.125–0.375 μmol/L) made the emulsion change from a cream-like state to a self-supporting gel. Results Rheological experiments confirmed that the telechelic DNA could improve the yield stress, storage modulus/loss modulus (Gʹ/Gʹʹ) and apparent viscosity of the emulsion gel in a concentration-dependent manner (0–0.375 μmol/L). Inverted fluorescence images clearly showed the interdroplet network of the emulsion gel linked by telechelic DNA. For 3D printing, the emulsion gel with a higher concentration (0.375 μmol/L) of telechelic DNA displayed better surface quality and dimensional resolution, indicating improved printability. Conclusion This study successfully designed a novel telechelic DNA-bridged emulsion gel, which showed great potential as edible ink for 3D printing.

Probing Molecular Chirality on the Self-Assembly and Gelation of Naphthalimide-Conjugated Dipeptides.

In this work, 1,8-naphthalimide (NMI)-conjugated three hybrid dipeptides constituted of a β-amino acid and an α-amino acid have been designed, synthesized, and purified. Here, in the design, the chirality of the α-amino acid was varied to study the effect of molecular chirality on the supramolecular assembly. Self-assembly and gelation of three NMI conjugates were studied in mixed solvent systems [water and dimethyl sulphoxide (DMSO)]. Interestingly, chiral NMI derivatives [NMI-βAla-lVal-OMe (NLV) and NMI-βAla-dVal-OMe (NDV)] formed self-supported gels, while the achiral NMI derivative [NMI-βAla-Aib-OMe, (NAA)] failed to form any kind of gel at 1 mM concentration and in a mixed solvent (70% water in DMSO medium). Self-assembly processes were thoroughly investigated using UV-vis spectroscopy, nuclear magnetic resonance (NMR), fluorescence, and circular dichroism (CD) spectroscopy. A J-type molecular assembly was observed in the mixed solvent system. The CD study indicated the formation of chiral assembled structures for NLV and NDV, which were mirror images of one another, and the self-assembled state by NAA was CD-silent. The nanoscale morphology of the three derivatives was studied using scanning electron microscopy (SEM). In the case of NLV and NDV, left- and right-handed fibrilar morphologies were observed, respectively. In contrast, a flake-like morphology was noticed for NAA. The DFT study indicated that the chirality of the α-amino acid influenced the orientation of π-π stacking interactions of naphthalimide units in the self-assembled structure that in turn regulated the helicity. This is a unique work where molecular chirality controls the nanoscale assembly as well as the macroscopic self-assembled state.

The impact of psyllium gelation behaviour on in vitro colonic fermentation properties

Psyllium is a viscous, gel forming fibre with properties that have led it to be used for alleviating gastrointestinal discomfort. We have used previously identified fractions of psyllium with differing flow properties. Fraction 1 (F1) forms a non-gelling solution containing rhamnose. galactose, and arabinose. Fraction 2 (F2) forms a fluid-like gel containing mainly xylose and arabinose, Fraction 3 (F3) has almost identical monosaccharide and linkage composition to F2, but forms an insoluble, self-supporting gel. We performed in vitro batch fermentation experiments seeded with human stool. Metabolomics were performed using 1H NMR, and FISH with calcofluor white and direct red 23 were used to visualise the gels after in vitro fermentation of the fractions. The total amount of gas and short chain fatty acid produced was significantly higher for F1, compared to F2 and F3. F3 gas production was significantly lower than F2, but metabolite production between F2 and F3 did not differ. All fractions preferentially lead to the production of propionate instead of butyrate and were produced in the ratio of 58:35:7, 54:38:8, and 61:33:6 (acetate: propionate: butyrate) for F1, F2, and F3 respectively. Microscopy showed differences in how the fractions broke down and demonstrated the localisation of bacteria on the outer edge of each fraction. These results suggest that for these psyllium fractions the structure is a key factor that determines fermentability. Flow properties may play a role in gas production, suggesting directions for future investigation. Isolated fractions may have clinical benefit above that of unrefined psyllium powder aiding in the treatment of gastrointestinal discomfort.

Accelerated lithium-ion diffusion via a ligand 'hopping' mechanism in lithium enriched solvate ionic liquids.

Solvate ionic liquids (SILs), equimolar amounts of lithium salts and polyether glymes, are well studied highly customisable "designer solvents". Herein the physical, thermal and ion mobility properties of SILs with increased LiTFSI (LiTFSA) concentration, with ligand 1 : >1 LiTFSI stoichiometric ratios, are presented. It was found that between 60-80 °C, the lithium cation diffuses up to 4 times faster than the corresponding anion or ligand (glyme). These systems varied from viscous liquids to self-supporting gels, though were found to thin exponentially when heated to mild temperatures (50-60 °C). They were also found to be thermally stable, up to 200 °C, well in excess of normal operating temperatures. Ion mobility, assessed under an electric potential via ionic conductivity, showed the benefit of SIL optimisation for attaining greater concentrations of Li+ cations to store charge during supercapacitor charging and discharging. Molecular dynamics simulations interrogate the mechanism of enhanced diffusion at high temperatures, revealing a lithium hopping mechanism that implicates the glyme in bridging two lithiums through changes in the denticity.

The effects of germination on the composition and functional properties of hemp seed protein isolate

The effects of germination on the functional properties of hemp seed protein isolates was evaluated in this study. Significant seed storage protein degradation was observed after three days of germination, while protein surface charge was altered after one day of germination. Protein solubility increased in neutral to slightly acidic pH, with 5-day germination increasing hemp seed protein solubility from 10.3% to 21.8% at pH 7.0. Water holding capacity increased from 1.03 g H 2 O/g isolate to 1.34 g H 2 O/g isolate while oil holding capacity stayed relatively constant. Germinated protein isolates demonstrated higher foaming capacity (69.2%–111.2%) and foaming stability (53.6%–75.1%) than non-germinated protein isolates. Five-day germinated hemp seed protein isolate was the only adequate emulsifier in this study, capable of stabilizing emulsion droplets down to 2.90 μm in diameter. Hemp seed protein formed self-supporting gels at minimum of 2 or 3 w/v %, and germination increased the hardness of hemp seed protein gels (38.02 g–49.12 g for 10 w/v % gels). These findings indicate the ability to leverage germination as a clean-label process for improving the functional properties of hemp seed protein. • Hemp seed storage proteins are degraded after three days of germination. • Germinated hemp seed protein isolates are more soluble near a neutral pH. • Germination improves hemp protein WHC, foaming, emulsifying, and gelling properties. • LGC for hemp protein at pH 7 was determined at 2–3 w/v %.

Insight into the self-assembly and gel formation of a bioactive peptide derived from bovine casein

The self-assembling and gelation properties of a bioactive peptide derived from bovine casein (FFVAPFPEVFGK) were studied in the peptide's natural form (uncapped, uncapFFV) and capped with protecting groups added to both termini (capped, capFFV). Although the natural peptide (uncapFFV) did not demonstrate self-assembly, the capped peptide (capFFV) spontaneously self-assembled and formed a self-supporting gel. Variations in peptide concentration and incubation time influenced the gel's mechanical properties, suggesting the peptide's properties could be tuned and exploited for different applications. These results suggest that food-derived bioactive peptides have good potential for self-assembly and therefore utilisation as gels in functional foods and nutraceuticals. Self-assembly is a natural phenomenon that occurs in many fundamental biological processes. Some peptides can self-assemble and form gels with tunable properties under given conditions. These properties, along with peptide bioactivity, can be combined to make unique biomaterials. Instead of synthesising the self-assembling bioactive peptides, we aim to extract them from natural sources. In order to use these peptides for different applications, it is essential to understand how we can trigger self-assembly and optimise the assembly conditions of these peptide gels. The self-assembling and gelation properties of a bioactive peptide derived from bovine casein (FFVAPFPEVFGK) were studied in the peptide's natural form (uncapped, uncapFFV) and capped with protecting groups added to both termini (capped, capFFV). Although the natural peptide (uncapFFV) did not demonstrate self-assembly, the capped peptide (capFFV) spontaneously self-assembled and formed a self-supporting gel. Variations in peptide concentration and incubation time influenced the gel's mechanical properties, suggesting the peptide's properties could be tuned and exploited for different applications. These results suggest that food-derived bioactive peptides have good potential for self-assembly and therefore utilisation as gels in functional foods and nutraceuticals.

Tunable oleosome-based oleogels: Influence of polysaccharide type for polymer bridging-based structuring

This research proposes a gelation method using soybean oleosomes as templates in combination with polysaccharides. Two anionic polysaccharides, sodium alginate, and xanthan gum were investigated for their ability to induce bridging flocculation. Bridging flocculation occurs when flexible polysaccharides such as alginate strongly interact with oppositely charged oleosome particles in acidic pH ranges. In contrast, the more rigid xanthan leads to a different flocculation mechanism, which is not driven by strong electrostatic attractive interactions. In microscopy images, xanthan induced microscopic and macroscopic phase separation between oleosome droplets and xanthan, presenting large, irregular-shaped particles. The ratio between alginate chains and oleosome droplets is critical for optimum bridging, where 0.005 g/g (also expressed as an equivalent per droplet surface area 0.4 mg/m2) induced extensive droplet flocculation. It is possible to obtain an interconnected droplet network at this optimum ratio. Upon densification at the optimum ratio, a compact and self-supporting gel of about 46 wt% starting from 5 wt% oleosome is obtained. Oscillatory rheology showed that gels at optimum bridging ratio have higher moduli (G’) than those formed at a different ratio, confirming a highly cross-linked network. Bridging flocculation provides an alternative method to design gels with predictable rheological properties suitable for food and drug design and cosmetic applications.

Pickering high internal phase emulsions with excellent UV protection property stabilized by Spirulina protein isolate nanoparticles

Herein, we reported the use of natural, renewable, and food-grade Spirulina protein isolate nanoparticles (SPI NPs) as effective particle stabilizers for Pickering high internal phase emulsions (Pickering-HIPEs). SPI NPs were prepared using a straightforward antisolvent technique and characterized using dynamic light scattering (DLS), and zeta potential measurement as well as scanning electron microscopy (SEM). SPI NPs were afterward used as sole stabilizers to prepare the oil-in-water (O/W) HIPEs, the effects of oil content, particle concentration, and pH of aqueous phase on the microstructure, stability, and rheological behaviors of the resulting Pickering-HIPEs were investigated. The Pickering-HIPEs generated showed a self-supporting gel network, a high oil content (up to 85 vol%), and extraordinary storage stability after prolonged storage and UV exposure. Concurrently, the Pickering-HIPEs provided good UV protection for a variety of photosensitive compounds, including β-carotene, vitamin E, and limonene. These findings would not only advance the development of biocompatible particle stabilizers for Pickering-HIPEs in cosmetic, food, and pharmaceutical industries, but they would also provide a guidance for the protection of photosensitive compounds.

High-Protein Foods for Dysphagia: Manipulation of Mechanical and Microstructural Properties of Whey Protein Gels Using De-Structured Starch and Salts.

This study focuses on understanding the effect of ionic strength on the mechanical and microstructural properties of novel composite gels containing 13% whey protein isolate (WPI) and 4% de-structured waxy potato starch (DWPS). The DWPS is a physically modified waxy potato starch treated at 140 °C for 30 min under constant shear. Thermodynamic incompatibility between WPI and DWPS was observed upon the addition of NaCl (~75 mM) or CaCl2 (10–75 mM). The combined effects of such thermodynamic incompatibility with the changes in protein connectivity induced by varied ionic strength led to the formation of distinctive gel structures (inhomogeneous self-supporting gels with a liquid centre and weak gels with paste-like consistency) that were different from thermodynamic compatible homogeneous self-supporting gels (pure WPI and WPI + maltodextrin gels). At ≥ 250 mM NaCl, instead of a paste-like texture, a recovered soft and creamy self-supporting gel structure was observed when using DWPS. The ability to generate a range of textures in WPI gelation-based foods by using DWPS under different ionic conditions, is a feasible strategy for formulating high-protein foods for dysphagia—aimed to be either thickened fluids or soft solids. Additionally, this acquired knowledge is also relevant when formulating food gels for 3-D printing.

Development and characterization of acid-induced whey protein concentrate and egg white protein composite gel

The thermal aggregate solutions were prepared by mixing whey protein concentrate (WPC) and egg white protein (EWP) with different protein mass ratios (3:0, 3:1, 1:1, 1:3, 0:3), and then WPC/EWP composite gels were induced by glucono-δ-lactone (GDL), respectively named WPC, WE3/1, WE1/1, WE1/3, and EWP. The texture properties, water holding capacity, color, thermal stability, rheological and structure properties of the gels were investigated. The results showed that with the increase of EWP content, the hardness, adhesiveness, resilience and gumminess of WPC/EWP composite gels gradually increased. EWP gel exhibited the highest water holding capacity (96.55%). Rheological analysis showed that the storage modulus and loss modulus of the gels showed an increasing trend. EWP gel had the lowest creep flexibility and the strongest resistance to deformation. The DSC test showed the thermal stability of WE1/1 gel was the best (Td=115.84 °C). SEM results showed the three-dimensional network structure of composite gel was more denser with EWP incorporation. The self-supporting gels prepared by mixing whey and egg white protein had more excellent performance than single WPC gel. The information generated from this study may provide opportunities to develop functional food formulations enriched with whey protein and egg white protein.

Structural and rheological properties of mung bean protein emulsion as a liquid egg substitute: The effect of pH shifting and calcium

The objective of this study was to develop functional egg substitutes using mung bean protein (MBP) through pH12-shifting modification and calcium addition. The influence of pH12-shifting and Ca2+ ions on emulsion stability and the physical properties of MBP-based emulsion gels were elucidated in a neutral (pH 7) composite system (7.2% MBP and 10% canola oil). Results showed that the pH12-treated MBP emulsions were stable even after 5-day storage at 25 °C. The pH12-shifting significantly decreased the average emulsion droplet size from 524 nm in emulsion of native MBP to 422 nm. The emulsion samples were further heated at 95 °C to induce the formation of gels. With the calcium addition of 0 or 5 mM, the pH12 MBP emulsion did not form self-supporting gels. In the presence of 10–20 mM Ca2+, emulsion gels prepared with pH12-treated MBP exhibited a uniform and compact network structure. The gel hardness, water-holding capacity, and water distribution of pH12-treated MBP emulsion gels were superior to that of the native MBP samples. This study demonstrated MBP-based emulsion gels can be improved by pH12-shifting treatment in combination with calcium addition, resulting in a similar texture to egg, hence, the potential to develop MBP-based egg substitutes.

Rheological and gelling properties of Nicandra physalodes (Linn.) Gaertn. pectin in acidic media

Nicandra physalodes (Linn.) Gaertn. polysaccharide (NPGP) was previously recognized as a pectic polysaccharide, with a high galacturonic acid content (87.8%) and a low methoxylation degree (28%). In the present study, it was found that NPGP can form self-supporting gels when cooling its heated solutions (2.0%, w/v) acidified by citric acid. It was demonstrated that the decrease in pH led to the suppression in electrostatic repulsions between the pectin chains, thereby promoting pectin chain-chain association mainly through hydrogen bonding. As the pH decreased from 3.2 to 2.4, the gel strength and gel thermal stability were continuously increased. Moreover, it was shown that sucrose addition slightly promoted the gelation and gel thermal stability of NPGP, but the effect of monovalent ions (Na+) and divalent ions (Ca2+) was not significant. Conclusively, our results indicate that NPGP is a new gelling polysaccharide that shows great potential in formulation of acidic gel foods.

Glycine-Rich Peptides from FUS Have an Intrinsic Ability to Self-Assemble into Fibers and Networked Fibrils.

Glycine-rich regions feature prominently in intrinsically disordered regions (IDRs) of proteins that drive phase separation and the regulated formation of membraneless biomolecular condensates. Interestingly, the Gly-rich IDRs seldom feature poly-Gly tracts. The protein fused in sarcoma (FUS) is an exception. This protein includes two 10-residue poly-Gly tracts within the prion-like domain (PLD) and at the interface between the PLD and the RNA binding domain. Poly-Gly tracts are known to be highly insoluble, being potent drivers of self-assembly into solid-like fibrils. Given that the internal concentrations of FUS and FUS-like molecules cross the high micromolar and even millimolar range within condensates, we reasoned that the intrinsic insolubility of poly-Gly tracts might be germane to emergent fluid-to-solid transitions within condensates. To assess this possibility, we characterized the concentration-dependent self-assembly for three non-overlapping 25-residue Gly-rich peptides derived from FUS. Two of the three peptides feature 10-residue poly-Gly tracts. These peptides form either long fibrils based on twisted ribbon-like structures or self-supporting gels based on physical cross-links of fibrils. Conversely, the peptide with similar Gly contents but lacking a poly-Gly tract does not form fibrils or gels. Instead, it remains soluble across a wide range of concentrations. Our findings highlight the ability of poly-Gly tracts within IDRs that drive phase separation to undergo self-assembly. We propose that these tracts are likely to contribute to nucleation of fibrillar solids within dense condensates formed by FUS.

Impact of pH on the physicochemical and rheological properties of mung bean (Vigna radiata L.) protein

This study aimed to investigate the structural characteristics and physicochemical properties of mung bean protein (MBP) at different pH levels. Structures and physicochemical properties were evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, circular dichroism, ultraviolet visible and fluorescence spectrophotometry, differential scanning calorimetry, etc. MBP contained six bands of 64, 62, 48, 32, 25 and 23 kDa, among which the 64, 48 and 32 kDa bands consisted of glycoproteins. The β-sheets and random coils of MBP had structures close to double α-helices and β-turns at pH 3.0, 7.0 and 9.0. MBP in an alkaline environment had higher solubility and free sulfhydryl contents, smaller particle sizes, and lower surface hydrophobicity. Rheological analysis showed that MBP at pH 3.0, 5.0, 7.0 and 9.0 exhibited shear-thinning pseudoplastic fluids. A higher shear stress was needed to initiate flow at pH 5.0 than at pH 3.0, 7.0 or 9.0. MBP (130 mg/mL) formed self-supporting gels at pH 7.0 and 9.0. MBP had good foaming capacity (125.00 %), emulsion activity index (117.05 m2/g) and emulsion stability index (20.86 min) in alkaline environment. These results provide fundamental information about MBP for use in neutral and alkaline environments as a functional food ingredient.