Soybean Protein Research Articles

PH-regulated Tannic acid and soybean protein isolate adhesive for enhanced performance in plant-based meat analogues

A food adhesive comprising tannic acid (TA) and soybean protein isolate (SPI) was developed to establish a cohesive bond between soy protein gel and simulated fat. The impact of varying TA concentrations and pH levels on the adhesive’s rheology, thermal stability, chemical structure, and tensile strength were investigated. Rheological results revealed a gradual decrease in adhesive viscosity with increasing TA content. Differential scanning calorimetry (DSC) and thermal gravimetric (TG) results indicated that the stability of the adhesive improved with higher TA concentrations, reaching its peak at 0.50% TA addition. The incorporation of TA resulted in the cross-linking of amino group in unfolded SPI molecules, forming a mesh structure. However, under alkaline conditions (pH 9), adhesive viscosity and stability increased compared to the original pH. This shift was due to the disruption of the SPI colloidal charge structure, an increase in the stretching of functional groups, further unfolding of the structure, and an enhanced binding of SPI to TA. Under the initial pH conditions, SPI reacted with TA's active site to form covalent crosslinked networks and hydrogen bonds. In alkaline condition, beyond hydrogen and ionic bonding, the catechol structure was oxidized, forming an ortho-quinone that crosslinked SPI and created a denser structure. Tensile strength measurements and freeze–thaw experiments revealed that the adhesive exhibited maximum tensile strength and optimal adhesion with 0.75% TA at pH 9, providing the best overall performance. This study provides a new formulation and approach for developing plant-based meat analogues adhesives.

Effect of pH‐shifting treatment on the structural characteristics and nutritional quality of the ultrasonically extracted protein isolate from soybean meal

AbstractSoybean meal is an underutilized byproduct of the soybean oil processing industry, which is rich in high quality protein but mostly used as an animal feed. Valorization of soybean meal on a large scale is possible by extracting protein isolate and modifying its structural characteristics through pH‐shifting or ultrasonic treatment, which has a direct association with the better functional properties of protein isolate. The present study aimed to evaluate the impact of pH‐shifting treatment on the structural characteristics and nutritional quality of ultrasonically extracted soybean meal protein isolate (SMPI). The results showed that the pH shifted SMPI had higher hydrophobicity (60.5–104.3) and free sulfhydryl group (22.67–24.45 μmol/g) than without pH shifted SMPI (53.5 and 19.67 μmol/g, respectively). The fluorescence intensity of the SMPI treated at extreme acidic and alkaline pH was higher than that of other pH‐treated samples. The ꞵ‐sheet (39.68%) components of SMPI treated at pH 10 showed the highest value when compared to other pH‐treated (38.18–39.26%). The alkaline pH‐treated sample had higher concentration of essential amino acids (36.16 g/100 g) than other acidic or near neutral pH‐treated sample (30.06–32.30 g/100 g). The quality parameters such as biological value (67.62), and amino acid index (72.77) were higher for the SMPI treated at pH 10 as compared to the SMPI treated at other pH conditions. Hence, the pH‐treatment method can be utilized as an effective technique to improve the characteristics of SMPI, which will increases its applications in various food sectors.Practical ApplicationsThe current investigation demonstrated that pH‐shifting treatment had a substantial impact on the structural and nutritional quality of the soybean meal protein isolate extracted by ultrasonication. Improvements in soybean meal protein's surface hydrophobicity, free sulfhydryl groups, and secondary structural components will expand its uses in the dairy, bread, meat, and infant food development industries, among other food sectors as these structural changes improve the functionality of protein. Furthermore, the treatment of soybean meal protein isolate with pH shifting led to a considerable increase in nutritional quality, as measured by the essential amino acid composition, essential amino acid index, and protein efficiency ratio, which is expected to increase its utilization in novel food product development.

Deciphering the interaction mechanism between soy protein isolate and fat-soluble anthocyanin on experiments and molecular simulations

In this work, the acylated anthocyanin (Ca-An) was prepared by enzymatic modification of black rice anthocyanin with caffeic acid, and the binding mechanism of Ca-An to soybean protein isolate (SPI) was investigated by experiments and computer simulation to expand the potential application of anthocyanin in food industry. Multi-spectroscopic studies revealed that the stable binding of Ca-An to SPI induced the folding of protein polypeptide chain, which transformed the secondary structure of SPI trended to be flexible. The microenvironment of protein was transformed from hydrophobic to hydrophilic, while tyrosine played dominant role in quenching process. The binding sites and forces of the complexes were determined by computer simulation for further explored. The protein conformation of the 7S and 11S binding regions to Ca-An changed, and the amino acid microenvironment shifted to hydrophilic after binding. The results showed that more non-polar amino acids existed in the binding sites, while in binding process van der Waals forces and hydrogen bonding played a major role hydrophobicity played a minor role. Based on MM-PBSA analysis, the binding constants of 7S-Ca-An and 11S-Ca-An were 0.518 × 106 mol−1 and 5.437 × 10−3 mol−1, respectively. This information provides theoretical guidance for further studying the interaction between modified anthocyanins and biomacromolecules.

Relationship between soybean protein composition and breaking load of heat-induced gel prepared from acid-precipitated soybean flour

To understand the effective soy protein composition for realizing appropriate meat substitute, we evaluated the contribution of four protein fractions separated from soybeans, two types of globulins and two types of lipophilic proteins, to textural properties of heat-induced gels prepared from an acid-precipitate of soybean flour (AP-SF). When we added these fractions sduring the preparation of AP-SF gels, which increased the protein content by 10%, the gel with 7S globulin displayed the highest breaking load (417.7 gf). With respect to combinatorial effects, the AP-SF gel that added with 5% 7S and 5% 11S globulin reached an even higher value (460.2 gf) than the value described above (417.7gf).To further support the contribution of fractions, we investigated the correlation between the content of these four protein fractions in soybean flour from different cultivars and the breaking load of the heat-induced gels. The breaking load shows a stronger correlation with the total amount of 7S and 11S (r = 0.86) than with 7S alone (r = 0.77), 11S alone (r = 0.70), or the total amount of acid-precipitated proteins (r = 0.80). Thorough this research, we obtained new findings suggesting a synergistic effect between both globulins.

Eco-friendly fiberboards with low formaldehyde content and enhanced mechanical properties produced with activated soybean protein isolate modified urea-formaldehyde resin

Urea-formaldehyde (UF) resin is one of the most widely used resin adhesive for wood-based panels. The main concern of UF resin bonded wood-based panels is formaldehyde emission and poor water resistance. In this study, activated soybean protein isolate (SPI) was used to modify UF resin for the production of eco-friendly fiberboard panels. The effects of different activated SPI on the properties of UF resins and the resin bonded medium-density fiberboard (MDF) panels were investigated. The free formaldehyde content of the urea-activated SPI modified UF resin was only 0.13 %. Approximately 27.8 % lower than that of the unmodified UF resin. The resin bonded MDF panel with a density of 760 kg/m3 shows a modulus of rupture (MOR) and modulus of elasticity (MOE) of 45.73 MPa and 4005 MPa, which is increased by 25 % and 15 % compared to the unmodified UF resin group. The internal bonding strength (IB) reaches 0.71 MPa, which is about 15 % higher than that of the unmodified UF resin group. The tested 24-hour thickness swelling (24 h TS) of the modified UF resin group is only 8.1 %. The tested formaldehyde content of the sodium dodecyl sulfate (SDS)-activated SPI modified UF resin bonded MDF panel is only 4.8 mg/100 g, which is 20 % lower than that of the control UF resin group. The activated SPI modified UF resin shows great improvement in bonding strength and lower formaldehyde content for MDF panels as compared to the pure UF resin. The chemical groups, crystalline properties, and thermal stability of the pure and the modified UF resins were characterized via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric (TG) analysis. It is confirmed that the activated SPI modified UF resin has similar chemical structure, higher ratio of crystalline regions, and slightly lower thermal stability with compared to the pure UF resin. This study proposes a practical and applicable solution for the utilization of eco-friendly UF resin in wood-based panel production.

Characteristics of Pickering emulsions stabilized by microgel particles of five different plant proteins and their application

Pickering emulsions stabilized by protein particles are of great interest for use in real food systems. This study was to investigate the properties of microgel particles prepared from different plant proteins, i.e., soybean protein isolate (SPI), pea protein isolate (PPI), mung bean protein isolate (MPI), chia seed protein isolate (CSPI), and chickpea protein isolate (CPI). MPI protein particles had most desirable Pickering emulsion forming ability. The particles of SPI and PPI had similar particle size (316.23 nm and 294.80 nm) and surface hydrophobicity (2238.40 and 2001.13) and emulsion forming ability, while the CSPI and CPI particle stabilized emulsions had the least desirable properties. The MPI and PPI particle stabilized Pickering emulsions produced better quality ice cream than the one produced by SPI particle-stabilized emulsions. These findings provide insight into the properties of Pickering emulsions stabilized by different plant protein particles and help expand their application in emulsions and ice cream.

Plastein reaction enhances the emulsifying and rheological properties of silver carp hydrolysates in oil-in-water emulsions

The plastein reaction was ubiquitously acknowledged for its capacity to enhance the functional properties of protein hydrolysates. Despite this, the specific impact of the plastein reaction on emulsification, a critical functional aspect of protein hydrolysates, remains incompletely understood. In this study, the plastein reaction in silver carp protein hydrolysate (SCPH) was explored. A detailed comparison between the primary product (PP) and the blended product (SCPH–P) in terms of their oil-water interfacial adsorption kinetics and the shear strain of oil-in-water emulsions was reported. The interfacial adsorption kinetics suggested that the higher molecular weight imparted a slow rate of diffusion, penetration, and reorganization to the PP compared to SCPH-P. Furthermore, the elevated surface hydrophobicity also resulted in higher surface activity (i.e., high interfacial pressure) for PP. Simultaneously, nonlinear rheological analysis revealed that PP possessed enhanced resistance to shear strain due to its strong affinity for the oil-water interface of emulsion. These improvements manifested in PP-stabilized emulsions with reduced mean particle size (71.6 μm–9.5 μm), diminished instability index (nearly 3-fold prolongation of stabilization time), and increased electrostatic repulsion (zeta potential values increased from 6-15 mV to 21–27 mV), which underscored a substantial enhancement in the emulsification of SCPH through the plastein reaction. Notably, the emulsifying and rheological properties of PP at a 1% (w/w) concentration were nearly equivalent to those of soybean protein isolate at 0.5% (w/w), highlighting the plastein reaction's innovative potential in utilizing SCPH as a promising emulsifier.

Stability and 3D-printing performance of high-internal-phase emulsions based on ultrafine soybean meal particles

There are numerous studies on the application of soybean whey protein in three-dimensional (3D) printing. In this study, the effects of soybean meal particles (5%, 6%, 7%, 8%, 9%, and 10%) and oil-phase concentrations (70%, 72%, 74%, 76%, and 78%) on the stability and 3D-printing performance of a soybean-meal-based high-internal-phase emulsion were investigated. The results showed that the particle size of the emulsion decreased with increasing soybean meal particle concentration, and that increasing the concentration of the oil phase improved the viscoelasticity of the emulsion. Rheological tests further showed that the higher storage modulus of the emulsion indicated better support and stability. The emulsion with 8% soybean meal-particles and 76% oil-phase concentration exhibited the best printing effect. This study provides an effective solution for the preparation of stabilized high-internal-phase emulsions of soybean meal particles suitable for 3D printing.

Conjugation of Soybean Proteins 7S/11S Isolate with Glucose/Fructose in Gels through Wet-Heating Maillard Reaction.

Conjugation with glucose (G) and fructose (F) via the Maillard reaction under the wet-heating condition is a natural and non-toxic method of improving the technological functions of 7S/11S proteins in different kinds of gels. It may be used as an affordable supply of emulsifiers and an excellent encapsulating matrix for gels. This study aimed to create a glucose/fructose-conjugated 7S/11S soy protein via the Maillard reaction. The conjugation was confirmed by determining the SDS-PAGE profile and circular dichroism spectra. In addition, these conjugates were comprehensively characterized in terms of grafting degree, browning degree, sulfhydryl content, surface hydrophobicity (H0), and differential scanning calorimetry (DSC) through various reaction times (0, 24, 48, and 72 h) to evaluate their ability to be used in food gels. The functional characteristics of the 7S/11S isolate-G/F conjugate formed at 70 °C, with a high degree of glycosylation and browning, were superior to those obtained at other reaction times. The SDS-PAGE profile indicated that the conjugation between the 7S and 11S proteins and carbohydrate sources of G and F through the Maillard reaction occurred. Secondary structural results revealed that covalent interactions with G and F affected the secondary structural components of 7S/11S proteins, leading to increased random coils. When exposed to moist heating conditions, G and F have significant potential for protein alteration through the Maillard reaction. The results of this study may provide new insights into protein modification and establish the theoretical basis for the therapeutic application of both G and F conjugation with soy proteins in different food matrixes and gels.

Rapid quantitative analysis of soybean protein isolates secondary structure by two-dimensional correlation infrared spectroscopy through pH perturbation

The infrared spectroscopy (IR) signal of protein is prone to being covered by impurity signals, and the accuracy of the secondary structure content calculated using spectral data is poor. To tackle this challenge, a rapid high-precision quantitative model for protein secondary structure was proposed. Firstly, a two-dimensional correlation calculation was performed based on 60 groups of soybean protein isolates (SPI) infrared spectroscopy data, resulting in a two-dimensional correlation infrared spectroscopy (2DCOS-IR). Subsequently, the optimal characteristic bands of the four secondary structures were extracted from the 2DCOS-IR. Ultimately, partial least squares (PLS), long short-term memory (LSTM), and bidirectional long short-term memory (BILSTM) algorithms were used to model the extracted characteristic bands and predict the content of SPI secondary structure. The findings suggested that BILSTM combined with 2DCOS-IR model (2DCOS-BILSTM) exhibited superior predictive performance. The prediction sets for α-helix, β-sheet, β-turn, and random coil were designated as 0.9257, 0.9077, 0.9476, and 0.8443, respectively, and their corresponding RMSEP values were 0.26, 0.48, 0.20, and 0.15. This strategy enhances the precision of IR and facilitates the rapid identification of secondary structure components within SPI, which is vital for the advancement of protein industrial production.

Potentially texture-modified food for dysphagia: Gelling, rheological, and water fixation properties of rice starch–soybean protein composite gels in various ratios

Starch and protein are essential biomacromolecules ubiquitous in foods that contribute to nutritional and textural properties. Understanding the gelling behavior of starch and proteins can help develop texture-modified foods. Herein, composite gels were created with various ratios of rice starch to soybean protein (constant solid content 12%). The International dysphagia diet standardization initiative (IDDSI) levels of rice starch–soybean protein composite gels with various ratios were evaluated. The texture, gelling behavior, rheological properties, and water fixation properties of rice starch–soybean protein gel were characterized. The results showed that soybean protein inhibit the gelatinization of rice starch by reducing the gelatinization viscosity. Rice starch could prevent the denaturation of soybean protein by preventing the structural transformation of protein. Rice starch and soybean protein antagonize each other to inhibit gelation. In addition, rice starch precedes soybean protein gel so that the network formation of rice starch and soybean protein is hindered by each other in the composite system. Obvious phase separation was observed in the rice starch–soybean protein composite gel. Disulfide and hydrogen bonds are affected by the proportions of rice starch and soybean protein and are the main intermolecular forces to maintain structure. Gels prepared with a mixture of rice starch and soybean protein had lower IDDSI levels, gel strength, modulus, and strain compared to single-component gels. All gels exhibit excellent water-holding capacity. Therefore, the rice starch–soybean protein composite gel can be used to prepare soft and moist texture-modified foods to meet the needs of patients with dysphagia.

Optimization of Ink Composition and 3D Printing Process to Develop Soy Protein-Based Scaffolds.

Inks based on soybean protein isolate (SPI) were developed and their formulations were optimized as a function of the ink heat treatment and the content of other biopolymers to assess the effects of protein-polysaccharides and protein-protein interactions. First, the rheological behavior of the inks was analyzed in relation to the polyvinyl alcohol (PVA) concentration employed (20, 25, and 30 wt%) and, as a result of the analysis, the ink with 25 wt% PVA was selected. Additionally, sodium alginate (SA) and gelatin (GEL) were added to the formulations to improve the viscoelastic properties of the inks and the effect of the SA or GEL concentrations (1, 2, and 3 wt%) was studied. All inks showed shear thinning behavior and self-supporting abilities. Among all the 3D printed scaffolds, those with higher SA (3 wt%) or GEL (2 and 3 wt%) content showed higher shape fidelity and were selected for further characterization. Texture profile analysis demonstrated that the scaffolds prepared with previously heat-treated inks containing 3 wt% GEL showed the highest strength. Additionally, these scaffolds showed a higher water-uptake capacity profile.

Protein plant factories: production and resource use efficiency of soybean proteins in vertical farming.

Controlled environment agriculture, particularly vertical farms (VF), also called plant factories, is often claimed as a solution for global food security due to its ability to produce crops unaffected by weather or pests. In principle, essential macronutrients of the human diet, like protein, could technically be produced in VF. This aspect becomes relevant in the era of protein transition, marked by an increasing consumer interest in plant-based protein and environmental challenges faced by conventional farming. However, the real question is: what does the cultivation of protein crops in VF imply in terms of resource use? To address this, a study was conducted using a VF experiment focusing on two soybean cultivars. With a variable plant density to optimize area use, and because of the ability to have more crop cycles per year, protein yield per square metre of crop was about eight times higher than in the open field. Assuming soy as the only protein source in the diet, the resources needed to get total yearly protein requirement of a reference adult would be 20 m2 of crop area, 2.4 m3 of water and 16 MWh of electricity, versus 164 m2, 111 m3 and 0.009 MWh in the field. The study's results inform the debate on protein production and the efficiency of VF compared to conventional methods. With current electricity prices, it is unlikely to justify production of simple protein crops in VF or promote it as a solution to meet global protein needs. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Modification mechanism of soybean protein isolate-soluble soy polysaccharide complex by EGCG through covalent and non-covalent interaction: Structural, interfacial, and functional properties

Soybean protein isolate was modified with polysaccharides and polyphenols to prepare a natural emulsifier with antioxidant capacity. Physicochemical, structural, interfacial, and functional properties of SPI-SSPS complex were investigated after covalent and non-covalent interacted with EGCG. SPI-SSPS-EGCG ternary complex with low EGCG concentrations (0.0625 and 0.125 mg/mL) showed a significant increase in absolute potential value and a decrease in turbidity. EGCG destroyed the original rigid structure of SPI-SSPS complex, and the covalent complexes had an ordered structure, while the non-covalent interaction resulted in disordered. The ternary complex with high EGCG concentrations (0.25 and 0.5 mg/mL) exhibited stronger EGCG binding capacity and lower surface hydrophobicity, which in turn affected its interfacial properties. The EAI and ESI of SPI-SSPS-EGCG covalent complex increased significantly, while the non-covalent complex had a significant change in EAI but no significant change in ESI with increasing EGCG concentration. The ternary complex showed significantly enhanced antioxidant capacity. The SPI-SSPS-EGCG ternary complex, with excellent antioxidant capacity and emulsifying property, making it suitable for emulsion delivery systems.

Construction of a soybean protein isolate/polysaccharide-based whole muscle meat analog: Physical properties and freeze-thawing stability study

A growing interest has arisen in recreating real meat by mimicking its texture characteristics and muscle fiber structure. Our previous work successfully created meat analog fiber based on soybean protein isolate (SPI) and sodium alginate (SA) with the wet-spinning method. In this work, we analyzed the microstructure, texture profile, and water retainability of the assembled plant-based whole muscle meat analog (PMA) made of SPI/SA-based meat analog fiber and systematically studied the effect of different combinations and contents of transglutaminase (TG), salt, and soybean oil on the rheological behavior of the formulated adhesive. The estimated optimal condition that has the most similar texture characteristic with real chicken breast meat is: for every 1:1 mass ratio of simulated plant meat fibers to the adhesive, add 0.1 % TG enzyme addition in the adhesive and 100 mM NaCl addition. The physical behavior of PMA during cryopreservation was investigated through freeze-thaw cycles and freezing times. The addition of a small amount of oil and salt can efficiently prevent the PMA through freezing conditions which is comparable with the addition of D-Trehalose (TD). Overall, this study not only created a plant-based whole muscle meat analog product that is similar in texture to real chicken breast meat but also provided a new direction for constructing fiber-rich structure protein-based muscle meat analogs and their further commercialization.

Preparation of soy protein isolate-naringin-chitosan protein gel: Synergistic effect of ohmic heating pre-treatment and chitosan addition

Soybean protein isolate (SPI)-Naringin (Nar) complex pre-aggregates were prepared by ohmic heating (OH) and protein gels were formed by adding chitosan (CS). The properties of the pre-aggregate, gel rheological properties, texture, and water holding capacity (WHC) were evaluated. For the properties of the SPI-Nar pre-aggregate, under an OH treatment of 6 V/cm, the α-helix and β-turn structures of the SPI-Nar pre-aggregate were found to be 17.72% and 15.30%, respectively, with a uniform particle size distribution. The surface hydrophobicity, total free sulfhydryl, and turbidity were measured to be 794, 6.54 μmol SH/g, and 0.364, respectively. Atomic force microscopy images showed an Rq value of 3.63 and a height of 14.5 nm. Regarding the properties of the SPI-Nar-CS protein gel, when the CS addition level was 3%, the gel (SPI-Nar-CS 3) exhibited the best rheological properties, with hardness, springiness, and cohesiveness values of 10.17 g, 0.79 mm, and 0.31, respectively. The WHC and LF-NMR analysis of the protein gel revealed that SPI-Nar-CS 3 exhibited a WHC of 90.67% and optimal LF-NMR imaging and apparent state. SEM images showed the best microstructure at this CS addition level. In addition, the synergistic mechanism between the OH treatment and CS addition in protein gel formation was discussed, providing a theoretical foundation for future applications in the food industry.

Combining different ionic polysaccharides and pH treatment improved functional properties of soybean protein amyloid fibrils through structural modifications

This paper reported the effects of different ionic polysaccharides (a cationic polysaccharide (chitosan, CTS), an anionic polysaccharide (high methoxyl pectin, HMP), and a neutral polysaccharide (dextran, DEX)) and pHs (2.0, 4.5, 7.0, and 9.0) on the structural and functional properties of soybean protein amyloid fibrils (SAF) under non-covalent interactions. The fluorescence spectroscopy, ζ-potential, surface hydrophobicity (H0), and turbidity analyses revealed that, at any pH, HMP had a greater effect on the structure of SAF than CTS or DEX. Electrostatic and hydrophobic interactions predominated between SAF and HMP. The addition of negatively charged HMP prevented the exposure of hydrophobic groups, the H0 and ζ-potential decreased. Moreover, compared to SAF, the rheological properties of SAF-HMP complexes were enhanced. In particular, at pH 2.0, HMP was crosslinked with SAF and changed the fibrils conformation, the foaming stability of SAF-HMP increased to 100%. Furthermore, at pHs 2.0 and 4.5, strong electrostatic repulsion occurred between CTS and SAF. Therefore, SAF-CTS exhibited the highest emulsifying activity index and emulsifying stability index, which are 58.21 m2/g and 41.76 min, respectively, followed by SAF-HMP. By contrast, DEX had the least influence on the fibrils. These results will give a hand for industrial production of soybean protein amyloid fibrils.

Blended-protein changes body weight gain and intestinal tissue morphology in rats by regulating arachidonic acid metabolism and secondary bile acid biosynthesis induced by gut microbiota.

The impact of dietary nutrients on body growth performance and the composition of gut microbes and metabolites is well-established. In this study, we aimed to determine whether dietary protein can regulate the physiological indexes and changes the intestinal tissue morphology in rats, and if dietary protein was a crucial regulatory factor for the composition, function, and metabolic pathways of the gut microbiota. A total of thirty male Sprague Dawley (SD) rats (inbred strain, weighted 110 ± 10g) were randomly assigned to receive diets containing animal-based protein (whey protein, WP), plant-based protein (soybean protein, SP), or a blended protein (soybean-whey proteins, S-WP) for a duration of 8weeks. To investigate the effects of various protein supplement sources on gut microbiota and metabolites, we performed a high throughput 16S rDNA sequencing association study and fecal metabolomics profiling on the SD rats. Additionally, we performed analyses of growth indexes, serum biochemical indexes, and intestinal morphology. The rats in S-WP and WP group exhibited a significantly higher body weight and digestibility of dietary protein compared to the SP group (P < 0.05). The serum total protein content of rats in the WP and S-WP groups was significantly higher (P < 0.05) than that in SP group, and the SP group exhibited significantly lower (P < 0.05) serum blood glucose levels compared to the other two groups. The morphological data showed the rats in the S-WP group exhibited significantly longer villus height and shallower crypt depth (P < 0.05) than the SP group. The gut microbial diversity of the SP and S-WP groups exhibited a higher level than that of the WP group, and the microbiomes of the WP and S-WP groups are more similar compared to those of the SP group. The Arachidonic acid metabolism pathway is the most significant KEGG pathway when comparing the WP group and the SP group, as well as when comparing the SP group and the S-WP group. The type of dietary proteins exerted a significant impact on the physiological indices of SD rats. Intake of S-WP diet can enhance energy provision, improve the body's digestion and absorption of nutrients, as well as promote intestinal tissue morphology. In addition, dietary protein plays a crucial role in modulating fecal metabolites by regulating the composition of the gut microbiota. Metabolomics analysis revealed that the changes in the levels of arachidonic acid metabolites and secondary bile acid metabolite induced by Clostridium_sensu_stricto_1 and [Eubacterium]_coprostanoligenes_group maybe the primarily causes of intestinal morphological differences.

Alcalase-hydrolyzed insoluble soybean meal hydrolysate aggregates: Structure, bioactivity, function properties, and influences on the stability of oil-in-water emulsions

We studied the influences of hydrolysis time on the structure, functional properties, and emulsion stability of insoluble soybean meal hydrolysate aggregates (ISMHAs). We assume that the ISMHAs produced by soybean meal can be used as emulsifiers to prepare stable emulsions. The molecular weights of these ISMHAs were below 53 kDa. After hydrolysis, a decrease in α-helices and an increase in random coils indicated that the soybean meal proteins were unfolding. Moreover, the fluorescence intensity, UV absorption, and surface hydrophobicity of ISMHAs increased. These results would contribute to their antioxidant activity and functional properties. Additionally, the 90-min ISMHA sample exhibited the highest ABTS+• scavenging activity (80.02 ± 4.55 %), foaming stability (52.92 ± 8.06 %), and emulsifying properties (emulsifying activity index of 97.09 m2/g; emulsifying stability index of 371.47 min). The 90-min ISMHA emulsion exhibited the smallest particle size and excellent storage stability. Soybean meal peptide by-product emulsifier has potential for sustainable application.

Effects of fibrillation combined with glycation by different chain length sugars on structural and functional properties of soybean protein

The key objective of this study was to investigate the effects of fibrillation combined with glycation of soybean protein isolate (SPI) on the protein structure and functional properties. SPI fibrils alone, glycated proteins and glycated fibrils with different chain lengths (glucose–G, maltose–M and dextran–D) were prepared and characterized by spectroscopy and microscopy methods. The results of the O-phthalaldehyde assay, ultraviolet–visible spectroscopy and fluorescent advanced glycation endproducts indicated the degree of glycation. The thioflavin T fluorescence assay, transmission electron microscopy (TEM) and Fourier-transform infrared (FTIR) spectroscopy results demonstrated that the fibril morphology improved, and more flexible and aggregated fibrils were produced after glycation, further improving the protein functional properties. With EAI and ESI values of 37.31 m2/g and 33.80%, respectively, the emulsifying properties of SPI fibrils glycated by dextran were higher than the others. Foam properties and antioxidant activity were highest for the fibrils glycated by glucose. These results are of scientific significance for in-depth understanding and reasonable regulation of protein functional properties for industrial production in a complex food system.