Exploring simple ways to avoid collecting highly 137Cs-contaminated Aralia elata buds for the revival of local wild vegetable cultures.

Collection and cooking of wild vegetables have provided seasonal enjoyments for Japanese local people as provisioning and cultural ecosystem services. However, the Fukushima Daiichi Nuclear Power Plant accident in March 2011 caused extensive radiocesium contamination of wild vegetables. Restrictions on commercial shipments of wild vegetables have been in place for the last 10 years. Some species, including buds of Aralia elata, are currently showing radiocesium concentrations both above and below the Japanese reference level for food (100 Bq/kg), implying that there are factors decreasing and increasing the 137Cs concentration. Here, we evaluated easy-to-measure environmental variables (dose rate at the soil surface, organic soil layer thickness, slope steepness, and presence/absence of decontamination practices) and the 137Cs concentrations of 40 A. elata buds at 38 locations in Fukushima Prefecture to provide helpful information on avoiding collecting highly contaminated buds. The 137Cs concentrations in A. elata buds ranged from 1 to 6,280 Bq/kg fresh weight and increased significantly with increases in the dose rate at the soil surface (0.10-6.50 µSv/h). Meanwhile, the 137Cs concentration in A. elata buds were not reduced by decontamination practices. These findings suggest that measuring the latest dose rate at the soil surface at the base of A. elata plants is a helpful way to avoid collecting buds with higher 137Cs concentrations and aid in the management of species in polluted regions.

Preparation and characterization of vitamin E/calcium/soy protein isolate nanoparticles for soybean milk beverage fortification.

Soybean milk is a rich plant-based source of protein, and phenolic compounds. This study compared the nutritional value of soybean milk, flour, soy protein isolate (SPI) and evaluated the impact of prepared vitamin E/calcium salt/soy protein isolate nanoparticles (ECSPI-NPs) on fortification of developed soybean milk formulations. Results indicated that soybean flour protein content was 40.50 g/100 g, that fulfills 81% of the daily requirement (DV%), the unsaturated fatty acids (USFs), oleic and linoleic content was 21.98 and 56.7%, respectively, of total fatty acids content. In soybean milk, essential amino acids, threonine, leucine, lysine achieved 92.70, 90.81, 77.42% of amino acid scores (AAS) requirement values respectively. Ferulic acid was the main phenolic compound in soybean flour, milk and SPI (508.74, 13.28, 491.78 µg/g). Due to the moisture content of soybean milk (88.50%) against (7.10%) in soybean flour, the latest showed higher nutrients concentrations. The prepared calcium (20 mM/10 g SPI) and vitamin E (100 mg/g SPI) nanoparticles (ECSPI-NPs) exhibited that they were effectively synthesized under transmission electron microscope (TEM), stability in the zeta sizer analysis and safety up to IC50 value (202 ug/mL) on vero cell line. ECSPI-NPs fortification (NECM) enhanced significantly phenolic content (149.49 mg/mL), taste (6.10), texture (6.70) and consumer overall acceptance (6.54). Obtained results encourage the application of the prepared ECSPI-NPs for further functional foods applications.

Soy Protein Concentrate Diets Inversely Affect LPS-Binding Protein Expression in Colon and Liver, Reduce Liver Inflammation, and Increase Fecal LPS Excretion in Obese Zucker Rats.

Dietary soy protein and soy isoflavones have anti-inflammatory properties. Previously, we reported that feeding soy protein concentrate diet (SPC) with low or high isoflavone (LIF or HIF) to young (seven-week-old) obese (fa/fa) Zucker rats inhibits lipopolysaccharide (LPS) translocation and decreases liver inflammation compared to a casein control (CAS) diet. The current study investigated whether SPC-LIF and SPC-HIF diets would reduce liver inflammation in adult obese Zucker rats fed a CAS diet. A total of 21 six-week-old male obese (fa/fa) Zucker rats were given CAS diet for 8 weeks to develop obesity then randomly assigned to CAS, SPC-LIF, or SPC-HIF (seven rats/group) diet for an additional 10 weeks. The expression of LPS-translocation, inflammation, and intestinal permeability markers were quantified by qPCR in liver, visceral adipose tissue (VAT), and colon. LPS concentration was determined in both the colon content and fecal samples by a Limulus amebocyte lysate (LAL) test. SPC-LIF and SPC-HIF diets significantly decreased liver LPS-binding protein (LBP) expression compared to CAS diet (p < 0.01 and p < 0.05, respectively). SPC-HIF diet also significantly decreased liver MCP-1 and TNF-α expression (p < 0.05) and had a trend to decrease liver iNOS expression (p = 0.06). In the colon, SPC-HIF diet significantly increased LBP expression compared to CAS diet (p < 0.05). When samples from all three groups were combined, there was a negative correlation between colon LBP expression and liver LBP expression (p = 0.046). SPC diets did not alter the expression of intestinal permeability markers (i.e., occludin, claudin 3, and zonula occludens-1) in the colon or inflammation markers (i.e., TNF-α and iNOS) in VAT or the colon. LPS levels in the colon content did not differ between any groups. Fecal LPS levels were significantly higher in the SPC-LIF and SPC-HIF groups compared to the CAS group (p < 0.01). In conclusion, SPC, particularly SPC with HIF, reduces liver LBP expression and inflammation makers (i.e., TNF-α and MCP-1 expression) in adult obese Zucker rats, likely by reducing LPS translocation.

Soybean isolate protein complexes with different concentrations of inulin by ultrasound treatment: Structural and functional properties.

The effects of ultrasound and different inulin (INU) concentrations (0, 10, 20, 30, and 40 mg/mL) on the structural and functional properties of soybean isolate protein (SPI)-INU complexes were hereby investigated. Fourier transform infrared spectroscopy showed that SPI was bound to INU via hydrogen bonding. All samples showed a decreasing and then increasing trend of α-helix content with increasing INU concentration. SPI-INU complexes by ultrasound with an INU concentration of 20 mg/mL (U-2) had the lowest content of α-helix, the highest content of random coils and the greatest flexibility, indicating the proteins were most tightly bound to INU in U-2. Both UV spectroscopy and intrinsic fluorescence spectroscopy indicated that it was hydrophobic interactions between INU and SPI. The addition of INU prevented the exposure of tryptophan and tyrosine residues to form a more compact tertiary structure compared to SPI alone, and ultrasound caused further unfolding of the structure of SPI. This indicated that the combined effect of ultrasound and INU concentration significantly altered the tertiary structure of SPI. SDS-PAGE and Native-PAGE displayed the formation of complexes through non-covalent interactions between SPI and INU. The ζ-potential and particle size of U-2 were minimized to as low as -34.94 mV and 110 nm, respectively. Additionally, the flexibility, free sulfhydryl groups, solubility, emulsifying and foaming properties of the samples were improved, with the best results for U-2, respectively 0.25, 3.51 µmoL/g, 55.51 %, 269.91 %, 25.90 %, 137.66 % and 136.33 %. Overall, this work provides a theoretical basis for improving the functional properties of plant proteins.

Homologous Overexpression of Tyrosinase in Trichoderma reesei and Its Application in Glycinin Cross-Linking.

Tyrosinase is capable of oxidizing tyrosine residues in proteins, leading to intermolecular protein cross-linking, which could modify the protein network of food and improve the texture of food. To obtain the recombinant tyrosinase with microbial cell factory instead of isolation tyrosinase from the mushroom Agaricus bisporus, a TYR expression cassette was constructed in this study. The expression cassette was electroporated into Trichoderma reesei Rut-C30 and integrated into its genome, resulting in a recombinant strain C30-TYR. After induction with microcrystalline cellulose for 7 days, recombinant tyrosinase could be successfully expressed and secreted by C30-TYR, corresponding to approximately 2.16 g/L tyrosinase in shake-flask cultures. The recombinant TYR was purified by ammonium sulfate precipitation and gel filtration, and the biological activity of purified TYR was 45.6 U/mL. The purified TYR could catalyze the cross-linking of glycinin, and the emulsion stability index of TYR-treated glycinin emulsion was increased by 30.6% compared with the untreated one. The cross-linking of soy glycinin by TYR resulted in altered properties of oil-in-water emulsions compared to emulsions stabilized by native glycinin. Therefore, cross-linking with this recombinant tyrosinase is a feasible approach to improve the properties of protein-stabilized emulsions and gels.

Effect of montmorillonite (MMT) on the properties of soybean meal protein isolate-based nanocomposite film loaded with debittered kinnow peel powder.

The synthetic, non-renewable nature and harmful effects of plastic packaging have led to the synthesis of eco-friendly renewable bio-nanocomposite film. The present work was aimed at the formulation and characterization of bio-nanocomposite film using soybean meal protein, montmorillonite (MMT), and debittered kinnow peel powder. The composition of film includes protein isolate (5% w/v), glycerol (50% w/w), peel powder (20% w/w), and MMT (0.5-2.5% w/w). Incorporation of MMT in soybean meal protein-based film loaded with kinnow peel powder showed lesser solubility (16.76-26.32%), and swelling ability (142.77-184.21%) than the film prepared without MMT (29.41%, & 229.41%, respectively). The mechanical properties like tensile strength of nanocomposite film improved from 9.41 to 38.69% with the increasing concentration of MMT. The water vapor transmission rate of the nanocomposite film was decreased by 3.45-17.85% when the MMT concentration increased. Fourier-transform infrared spectroscopy and X-ray diffraction analysis showed no considerable change in the structural properties of the film after the addition of MMT. Differential scanning colorimeter analysis revealed the increment in melting temperature (85.33-92.67 °C) of the film with a higher concentration of MMT. Scanning electron microscopy analysis indicated an increased distributed area of MMT throughout the film at higher concentrations. The antimicrobial activity of the film was remarkably increased by 4.96-17.18% with the addition of MMT. The results obtained in the current work confirmed that MMT incorporation in soybean meal protein-based film can augment its properties and can be utilized for enhancing the storage period of food products.

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.

Integrated Transcriptome and Proteome Analyses of ß-Conglycinin-Induced Intestinal Damage in Piglets.

ß-conglycinin (ß-CG) induces intestinal damage in piglets; however, its regulatory mechanisms are not fully understood. This study aimed to investigate the molecular mechanisms by which ß-CG regulates intestinal injury in piglets through downstream genes and proteins. Our findings revealed that ß-CG significantly reduced villus height while increasing the crypt depth. In addition, we analyzed the transcriptome and proteome of jejunum tissues after the ß-CG treatment. In total, 382 differentially expressed genes (DEGs) and 292 differentially expressed proteins (DEPs) were identified between the treatment and the control groups. The expression levels of DEGs and DEPs were validated by using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blotting, respectively. The findings revealed a consistent correlation between their expression levels and transcriptomic and proteomic data. In addition, Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of DEGs and DEPs revealed their enrichment in oxidation-related GOs, as well as in lysosome-related pathways. A protein-protein interaction (PPI) regulatory network was constructed based on the DEPs. The integration of transcriptomic and proteomic analyses identified six genes that were significantly different at both the transcript and the protein levels. This study provides valuable insights into the molecular mechanisms underlying ß-CG-induced intestinal injury in piglets.

Anti-Obesity Effect and Signaling Mechanism of Potassium Poly-γ-Glutamate Produced by Bacillus subtilis Chungkookjang in High-Fat Diet-Induced Obese Mice.

The purpose of this work was to examine the effects of potassium poly-γ-glutamate (PGA-K) on mice fed a high-fat diet consisting of 60% of total calories for 12 weeks. PGA-K administration reduced the increase in body weight, epididymal fat, and liver weight caused by a high-fat diet compared to the obese group. The triglyceride, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol levels, which are blood lipid indicators, were significantly increased in the obese group but were significantly decreased in the PGA-K-treated group. The administration of PGA-K resulted in a significant inhibition of pro-inflammatory cytokines, including tumor necrosis factor α and interleukin 6. Moreover, the levels of leptin and insulin, which are insulin resistance indicators, significantly increased in the obese group but were significantly decreased in the PGA-K-treated group. These results suggest that PGA-K exhibits a protective effect against obesity induced by a high-fat diet, underscoring its potential as a candidate for obesity treatment.

Establishing a novel ternary complex of soybean protein isolated-tannic acid-magnesium ion and its properties.

A ternary complex composed of soybean protein isolated (SPI), tannic acid (TA) and magnesium ion (M) was established to enhance the capability of protein carriers for TA delivery. SPI was firstly covalently bind with TA (TA-SPI) and then M was employed to form the ternary complex (M-TA-SPI). Their structures, gel and digestion properties were further investigated. TA was observed to covalently bind with SPI. TA-SPI and M-TA-SPI complexes showed different molecule size and spatial structures after binding with M and TA. The increasing of TA amount changed the intramolecular interactions, microstructure and texture properties of M-TA-SPI gels. Compared with TA-SPI, M retarded the gastric digestion of M-TA-SPI and caused higher TA release amount in intestinal tract. In this study, M-TA-SPI was determined to be a good carrier to protect and release TA in gastrointestinal digestion. This kind of complex may have potential applications for loading polyphenols in nutraceuticals.

Novel a-linolenic acid emulsions stabilized by octenyl succinylated starch -soy protein-epigallocatechin-3-gallate complexes: Characterization and antioxidant analysis.

In this study, octenyl succinylated starch (OSAS)-soy protein (SP)-epigallocatechin-3-gallate (EGCG) complexes were designed to enhance the physical and oxidative stability of α-linolenic acid emulsions. Formations of OSAS-SP-EGCG complexes were confirmed via particle size, ξ-potential, together with fourier transform infrared (FTIR). A mixing ratio of 1:2 for OSAS to SP-EGCG resulted in ternary complexes with the highest contact angle (59.69°), indicating the hydrophobicity. Furthermore, the characteristics of α-linolenic acid emulsions (oil phase volume fractions (φ) of 10% and 20%) stabilized by OSAS-SP-EGCG complexes were investigated, including particle size, ξ-potential, emulsion stability, oxidative stability, and microstructure. These results revealed exceptional physical stability together with enhanced oxidative stability for these emulsions. Particularly, emulsions utilizing complexes having a 1:2 OSAS to SP-EGCG ratio exhibited superior emulsion stability. These findings provide theoretical support to the development of emulsions containing high levels of α-linolenic acid and for the broader application of α-linolenic acid in food products.

Role of pectin in the delivery of ß-carotene embedded in interpenetrating emulsion-filled gels made with soy protein isolate.

This study investigated the effects of different matrices on gel properties, lipid digestibility, ß-carotene bioaccessibility, released free amino acids and gel network degradation. Microstructure studies have proven that sugar beet pectin/soy protein isolate-based emulsion-filled gel (SBP/SPI-E) with interpenetrating networks was formed. SBP/SPI-E exhibited higher hardness (2.67 N, p < 0.05) and released lesser free amino acids (269.48-µmol/g SPI) than soy protein isolate-based emulsion-filled gel (SPI-E) in simulated intestinal fluid (SIF); however, both had similar free amino acids contents in simulated colonic fluid. SBP has the potential to delay gel network degradation in SIF, as evidenced by the sugar stain strips of SDS-PAGE and microstructure observation. Furthermore, SBP/SPI-E and SPI-E exhibited similar ß-carotene bioaccessibility in SIF, suggesting that SBP from composite gel could not affect the aforementioned bioaccessibility. The study provides useful information for the design of functional gels in the application of fat-soluble nutrient delivery.

Comparison of the physical stability, microstructure and protein-lipid co-oxidation of O/W emulsions stabilized by l-arginine/l-lysine-modified soy protein hydrolysate.

This work investigated the physical stability, microstructure, and oxidative stability of the emulsions prepared by soy protein hydrolysate (SPH) after modification with different concentrations of l-arginine and l-lysine. l-Arginine and l-lysine significantly increased the absolute zeta potential values, and decreased droplet sizes of the emulsions, thereby improving the physical stability of the emulsions. Meanwhile, l-arginine and l-lysine markedly decreased the apparent viscosity of the emulsions. The measurement of interfacial protein adsorption percentage showed that l-arginine (≤0.5 %) promoted the adsorption of SPH at the oil-water interface, whereas l-lysine (≤1%) reduced the adsorption of SPH at the oil-water interface. In addition, l-arginine and l-lysine (≤0.5 %) could retard lipid and protein oxidation. Correlation analysis indicated that the improvement in the physical stability of the emulsions by l-arginine and l-lysine also enhanced the oxidative stability of the emulsions. In summary, l-arginine and l-lysine could be effective modifiers for the protein-based emulsion systems.

Modification of soy protein isolate and pea protein isolate by high voltage dielectric barrier discharge (DBD) atmospheric cold plasma: Comparative study on structural, rheological and techno-functional characteristics.

The modification in structural, rheological, and techno-functional characteristics of soy and pea protein isolates (SPI and PPI) due to dielectric barrier discharge cold plasma (DBD-CP) were assessed. The increased carbonyl groups in both samples with cold plasma (CP) treatment led to a reduction in free sulfhydryl groups. Moreover, protein solubility of treated proteins exhibited significant improvements, reaching up to 59.07 % and 41.4 % for SPI and PPI, respectively, at 30 kV for 8 min. Rheological analyses indicated that storage modulus (G') was greater than loss modulus (G″) for CP-treated protein gels. Furthermore, in vitro protein digestibility of SPI exhibited a remarkable improvement (4.78 %) at 30 kV for 6 min compared to PPI (3.23 %). Spectroscopic analyses, including circular dichroism and Fourier Transform-Raman, indicated partial breakdown and loss of α-helix structure in both samples, leading to the aggregation of proteins. Thus, DBD-CP induces reactive oxygen species-mediated oxidation, modifying the secondary and tertiary structures of samples.

Unraveling the binding mechanism between soybean protein isolate and selected bioactive compounds.

The present study was aimed to investigate the interactions between soybean protein isolate (SPI) with resveratrol (RESV) and lutein (LUT). The binding forces, molecular interactions and functional properties were explored by multi-spectroscopic analysis, molecular docking and functional property indexes between SPI and RESV/LUT. The RESV/LUT quenched SPI chromophore residues with static mechanism and the endothermic reaction. The SPI- RESV/LUT complexes were formed through hydrogen bond, electrostatic and hydrophobic interactions. Molecular docking confirmed van-der-Waals force as one of the important forces. The interaction of RESV/LUT led to SPI's secondary structure alterations with a decrease in α-helix and random coil and an increase in ß-sheet and ß-turns. RESV/LUT developed foaming and emulsifying properties of SPI and showed a significant decrease of the surface hydrophobicity with RESV/LUT concentrations increase attributed to SPI's partial unfolding. Our study exposed molecular mechanisms and confirmations to understand the interactions in protein- RESV/LUT complexes for protein industrial base promotion.

Hawthorn pectin/soybean isolate protein hydrogel bead as a promising ferrous ion-embedded delivery system.

In this study, hydrogel beads [SPI/HP-Fe (II)] were prepared by cross-linking soybean isolate protein (SPI) and hawthorn pectin (HP) with ferrous ions as a backbone, and the effects of ultrasound and Fe2+ concentration on the mechanical properties and the degree of cross-linking of internal molecules were investigated. The results of textural properties and water-holding capacity showed that moderate ultrasonic power and Fe2+ concentration significantly improved the stability and water-holding capacity of the hydrogel beads and enhanced the intermolecular interactions in the system. Scanning electron microscopy (SEM) confirmed that the hydrogel beads with 60% ultrasonic power and 8% Fe2+ concentration had a denser network. X-ray photoelectron spectroscopy (XPS) and atomic absorption experiments demonstrated that ferrous ions were successfully loaded into the hydrogel beads with an encapsulation efficiency of 82.5%. In addition, in vitro, simulated digestion experiments were performed to understand how the encapsulated Fe2+ is released from the hydrogel beads, absorbed, and utilized in the gastrointestinal environment. The success of the experiments demonstrated that the hydrogel beads were able to withstand harsh environments, ensuring the bioactivity of Fe2+ and improving its bioavailability. In conclusion, a novel and efficient ferrous ion delivery system was developed using SPI and HP, demonstrating the potential application of SPI/HP-Fe (II) hydrogel beads as an iron supplement to overcome the inefficiency of intake of conventional iron supplements.

IAVPGEVA: Orally Available DPP4-Targeting Soy Glycinin Derived Octapeptide with Therapeutic Potential in Nonalcoholic Steatohepatitis.

IAVPGEVA, an octapeptide derived from soybean 11S globulin hydrolysis, also known as SGP8, has exhibited regulatory effects on lipid metabolism, inflammation, and fibrosis in vitro. Studies using MCD and HFD-induced nonalcoholic steatohepatitis (NASH) models in mice show that SGP8 attenuates hepatic injury and metabolic disorders. Mechanistic studies suggest that SGP8 inhibits the JNK-c-Jun pathway in L02 cells and liver tissue under metabolic stress and targets DPP4 with DPP4 inhibitory activity. In conclusion, the results suggest that SGP8 is an orally available DPP4-targeting peptide with therapeutic potential in NASH.

Optimization and characterization of high internal phase double emulsion (HIPDE) stabilized by with soybean protein isolate, gallic acid and xanthan gum.

This study aims to formulate a stable high internal phase double emulsion (HIPDE) using soybean protein isolate (SPI), gallic acid (GA), and xanthan gum (XG). To prepare HIPDE, W1/O was formulated with the water phase dispersed in the oil phase using polyglycerol polyricinoleate (PGPR) as a stabilizer. Thereafter, W1/O dispersed in W2 (SPI solution) was used. To stabilize the HIPDE, GA was added in W1 (0 or 1 %), XG was added in W2 (0 or 1 %), and the pH of the W phases was adjusted to acidic, neutral, and basic. The samples containing GA in W1 and XG in W2 did not phase out during the storage periods and maintained a higher ζ-potential value, a higher apparent viscosity, and a more sustainable droplet compared to others. These results were derived by the interaction between SPI and XG, SPI and GA, or GA and PGPR. Physicochemical crosslinks were formed, such as gallate-derived groups, SPI-GA complexation (Michael addition, Shiff base reaction), and hydrogen bonding. In conclusion, applying the SPI, GA, and XG to HIPDE would contribute to various industries such as food, medicine, and cosmetics.

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.

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, ß-sheet, ß-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.