Modified Soy Protein Research Articles

Soy proteins modified using cavitation jet technology

Soy proteins are seen as a promising alternative food source for meat with environmentally friendly properties. The problem is that the functional properties of soy proteins do not meet the needs of the food industry, and some existing modification technologies have adverse effects. Recently, cavitation jet technology (CJT) has been studied because it generates high heat, high pressure, strong shear and strong shock waves. This review summarizes the history and mechanism of cavitation jets. The energy generated during the cavitation jet process can open molecular structures, and the shock waves and microjets generated can pulverize the materials by erosion. The impact of the CJT on the morphology, structure, and functionality of soy proteins is discussed. The impact of combining CJT with other techniques on the production of soy proteins was also reviewed. The modification of proteins using two or more methods with complementary strengths, avoiding the disadvantages of certain techniques, makes the modification of proteins more effective. One of the most prominent effects is the combined treatment of cavitation jets with physical techniques. Finally, the review provides a comprehensive analysis of the application of modified soy proteins in the food industry and highlights promising avenues for future research.

Advancing self‐healing soy protein hydrogel with dynamic Schiff base and metal‐ligand bonds for diabetic chronic wound recovery

AbstractTo address the unique challenges of diabetic wound healing, wound dressings, particularly multifunctional hydrogels have garnered considerable interest. For the first time, a novel environmentally friendly soy protein‐based hydrogel is developed to accelerate the healing of diabetic chronic wounds. Specifically, this hydrogel framework is in direct formation through the dynamic Schiff base between oxidized guar gum and epigallocatechin‐3‐gallate (EGCG)‐modified soy protein isolate. Meantime, the addition of Ag+ enhances the cross‐linking of the hydrogel network by forming metal‐ligand bonds with the catechol groups in EGCG. Interestingly, the stretchability (up to 380%), swelling, and rheology properties of the hydrogel can be controlled by fine‐tuning the density of metal‐ligand bonds, endowing them with a high potential for precise matching. Additionally, various dynamic bonds endow hydrogel with excellent self‐healing ability, adhesiveness, and injectability. This hydrogel also exhibits good antibacterial properties, biocompatibility, and cell migration capabilities. Both in vivo and in vitro experiments demonstrated the outstanding anti‐inflammatory capacity of the hydrogel and its ability to modulate macrophage polarization. Consequently, the hydrogel has proven effective in promoting wound healing in a diabetic full‐thickness wound model through enhanced angiogenesis and collagen deposition. This eco‐friendly plant protein hydrogel offers a sustainable solution for wound care and environmental protection.

Soy protein particles as stabilizers of heat-stable O/W emulsions with 20% protein content

In response to the increasing demand for nutritionally rich foods, consumer preference for protein-enriched beverages has grown. However, heat-induced protein aggregation and gelation significantly hinders the production of high-protein drinks. In this study, oil-in-water (O/W) emulsions with exceptional thermal stability were formulated using modified soy protein particles (MSPs). These MSPs effectively resisted gel formation, even at a protein concentration of up to 20% (w/v). In contrast, emulsions prepared with untreated soy proteins (SPs) experienced pronounced gelation under identical conditions. The compact structure of MSPs, in comparison to SPs, imparted resistance to heat-induced denaturation and aggregation. Additionally, the emulsion displayed heightened heat processing insensitivity, due to the enhanced hydrophobicity of MSPs and their rapid adsorption at the oil-water interface, resulting in a denser, more elastic, and resilient interfacial film. These findings provide practical insights for the formulation of protein-rich milk alternatives, meeting the evolving market demands.

Structural characterization of modified soy protein isolate composite coatings and its application on fresh-cut cantaloupe (Cucumis melo cv. Xiaomi)

Fresh-cut cantaloupe is very perishable due to the mechanical damage and susceptibility to microorganism infections, which limit their shelf life. Cantaloupe is a popular fruit with high moisture content and nutritional value. This study aimed to enhance fresh-cut cantaloupe quality and extend the shelf life by employing soy protein isolates (SPI) coating solutions containing calcium lactate (CaL) and λ-aminobutyric acid (GABA). Cold plasma (CP) was used to augment the antioxidant and antimicrobial activities of the coatings. The coatings were meticulously characterized, and their impact on fresh-cut cantaloupe was assessed through physicochemical and microbiological parameters. The incorporation of CaL and GABA and the CP treatment heightened the antioxidant activity of the SPI coating, resulting in a substantial increase in DPPH and ABTS free radical scavenging activities by 58% and 30%, respectively. Application of the composite coating included a noteworthy 24% reduction in water loss on fresh-cut cantaloupe, maintaining color stability and total soluble solids content. Moreover, the treatment of composite coating effectively controlled microbial growth, ensuring fresh-cut cantaloupe remained in an edible state at the conclusion of the storage period. The coating treatment has extended the shelf life of fresh-cut cantaloupe from 6 d to 10 d at 0 °C. In conclusion, the CP-treated bioactive coating containing CaL and GABA prolonged the shelf life, enhanced nutritional value, and preserved the microbial quality attributes of fresh-cut cantaloupe.

Co-delivery mechanism of curcumin/catechin complex by modified soy protein isolate: Emphasizing structure, functionality, and intermolecular interaction

Modifying proteins to enhance their affinity for polyphenols is essential for developing a practical and efficient delivery system that promotes the synergistic effects of bioactive substances. The study investigated the nanoparticle complexation in both pure soy protein isolate (SPI) or SPI modified by ultrasonic combined heat treatment (UHSPI) with varying concentrations of curcumin/catechin (CU/CA) complex, and its effects on the functionality, structure and conformational changes of protein-polyphenol nanocomplexes. Additionally, the intermolecular interaction and co-delivery mechanisms of nanocomplexes were analyzed. Results showed that the physical modification process (28/40 kHz, 90 °C, 15 min) and a rational concentration of CU/CA (0.6 mg/mL) improve the encapsulation efficiency of polyphenols by SPI (up to 77% for curcumin, and 93% for catechin), resulting in a higher DPPH and ABTS scavenging capacity, along with the highest emulsification activity index, as well as enhanced storage stability and thermal stability. The interaction between UHSPI and CU/CA disrupted the protein's secondary structure and exposed more hydrophobic residues to a hydrophilic environment, and exhibited stronger fluorescence quenching. Molecular docking analysis revealed that protein-polyphenol interactions primarily relied on hydrogen bonds and hydrophobic interactions, and 11S subunits exhibited higher affinity with CU/CA. FTIR, fluorescence spectra, and XRD further confirmed the enhanced interaction ability between UHSPI and CU/CA, resulting in the formation of a more stable nanocomplex. Overall, the modified SPI effectively facilitates the co-delivery of an appropriate concentration of curcumin/catechin complex.

Effect of flaxseed-derived diglyceride-based high internal phase Pickering emulsion on the quality characteristics of reformulated beef burgers

The study aimed to fabricate healthier beef burgers using high internal phase Pickering emulsion (HIPPE) as animal fat substitute. In this context, HIPPE stabilized by modified soy protein isolates was produced with flaxseed-derived diglycerides (DAGs). Beef burgers were prepared by substituting beef backfat with HIPPE at varying levels (0%, 25%, 50%, 75%, and 100%). Reformulated burgers showed a significant decrease in WHC (from 89.75 to 77.38%), pH (from 5.73 to 5.58), L* values (from 53.5 to 44.5), and b* values (22.9 to 21.8), while a significant increase in a* values (from 24.4 to 6.7), cooking loss (from 20.25 to 30.62), and cooking shrinkage (from 11.27 to 13.05). Texture attributes, including hardness, chewiness, and gumminess, decreased up to 50% fat substitution and increased with increasing levels of fat substitution. Moreover, the rheological properties (G′ and G′′) and T2 relaxation time were increased with increasing fat replacement. The reformulation with HIPPE resulted in a decrease in SFA (from 3896 to 1712 mg/100 g), ω-6/ω-3 ratio (from 5.29 to 0.47), atherogenic index (from 0.57 to 0.13), and thrombogenic index (from 1.46 to 0.15) and increase in PUFA/SFA ratio (from 0.20 to 2.79). Notably, burgers with 50% fat substitution were more preferred regarding tenderness, while those with 100% fat substitution obtained higher scores for color and flavor than all other treatments. In conclusion, 50% fat replacement using flaxseed-derived diglyceride-based HIPPE improved beef burgers' textural profile and fatty acid composition without compromising the sensory characteristics.

Performance of eco-friendly soy protein adhesive reinforced by aldehyde sodium alginate

Faced with many challenges such as energy crisis and environmental protection issues, biomass soy protein-based adhesives for replacing aldehyde-based adhesives have gradually become one of the research hotspots for wood industry upgrading. However, soy protein-based adhesives still have many shortcomings. Low bonding strength, poor water resistance and high viscosity restrict their widespread industrial application. In this work, a modified soy protein isolate (SPI) based adhesive with strong water-resistant bonding strength and low viscosity was prepared. Oxidized sodium alginate (OSA) and calcium ions were employed in SPI adhesive system. Results showed that cross-linking between OSA, calcium ions and SPI occurred successfully. The mechanical properties of SPI were significantly improved. The dry and wet bond strengths were 2.05 MPa and 0.97 MPa, respectively, in 65.3 % and 49.2 % increments for comparison. The adhesive samples also showed a reduction in viscosity and an increase in thermal stability. It can be developed as a facile method for preparing bio-adhesives.

Insight into succinylated modified soy protein isolate-sodium alginate emulsion gels: Structural properties, interactions and quercetin release behavior

In this study, the emulsion gel system was constructed by succinylated SPI (SSPI) emulsion together with sodium alginate (Alg). The aim was to evaluate the influence of succinylation and Alg concentration (0 %, 1 %, 1.5 %, 2 %, 2.5 %, w/v) on the emulsion gel structure and formation mechanism, the encapsulation efficiency, release behavior, and digestion properties of quercetin. The succinylation modification and the increase in Alg concentration improved the textural properties of the emulsion gels and SSPI-2 % showed the optimum water-holding capacity (91.37 %). Fourier transform infrared spectroscopy, intermolecular forces, and X-ray diffraction indicated the formation of the gel network dominated by electrostatic interactions and hydrogen bond stabilization, with a decrease in the crystal size and disruption of the molecular rigidity structure. Low-field nuclear magnetic resonance, rheology, and microstructures showed the improvement of the moisture distribution of the gels and the formation of denser and more homogeneous. The quercetin delivery properties of SSPI emulsion gels were enhanced compared to SPI emulsion gels. The encapsulation rate of quercetin was further enhanced with increasing Alg concentration, and the optimum was reached at SSPI-2 % (96.40 %). The Ritger-Peppas model describes quercetin from SPI and SSPI gels regulated by different release kinetics in gastrointestinal fluids with a favorable sustained release effect. In addition, SSPI-2 % exhibited the highest quercetin bioaccessibility (74.54 %) and chemical stability (66.81 %). This research provides novel perspectives to explore the development of innovative emulsion gels and transport systems for bioactive.

Heterologous expression of protein-glutaminase in Escherichia coli Nissle 1917 for improved flavor properties of soy protein and its implications on high-moisture extrudates

Beany flavor affects sensory experience of soy protein-based food. Deamidation is an effective approach to improve the flavor of soy protein, but excessive hydrolysis has a negative effect on its molecular structure and processing property. In this study, protein-glutaminase (PG; EC 3.5.1.44) was heterologous expressed in E. coli Nissle 1917 (EcN) and used to specifically modify soy protein isolate (SPI) for improved flavor properties of textured protein. A fluorescence-based enzyme activity screening method was developed and optimized for fermentation conditions. After screening for optimal fermentation conditions based on cell fluorescence intensity, 3.01 U/mL of PG activity was achieved. SPI was treated with PG (0–24 h), and the degree of deamidation (DD) rapidly increased to 47.4% within 0–2 h. There was no significant decrease in the molecular weight of deamidated SPI (DSPI) after specific deamidation of PG within 0–10 h. The contents of main beany flavor substances (e.g., hexanal, benzaldehyde, and 2-pentylfuran) in DSPI decreased significantly with increasing DD. Compared with soy protein, moderate deamidation did not affect the processing properties and fibrous structure of DSPI in preparing high-moisture extrudates, while the structure of the extrudate decreased after a deamidation time of more than 6 h. This finding developed a safe expression system for PG and provided a promising method to address beany flavor in soy-based meat analogues produced by high moisture extrusion.

Hexagonal plate ultrasound pretreatment on the correlation between soy protein isolate structure and cholesterol-lowering activity of peptides, and protein's enzymolysis kinetics, thermodynamics

In this study, a hexagonal plate ultrasound (HPU) pretreatment technology was employed to modify soy protein isolate (SPI) and enhance the hypocholesterolemic activity of enzymatic digests from SPI. Results demonstrated that under the condition of ultrasound power density of 40 W/L, the hypocholesterolemic activity of enzymatic digests from HPU-pretreated SPI (HPU-SPI) increased by 88.40 % compared to control group after gastrointestinal digestion. The sulfhydryl content of HPU-SPI increased by a maximum of 45.32 % compared to control group. Fourier transform infrared and scanning electron microscopy revealed that HPU pretreatment partially unfolded the SPI conformation, reduced the intermolecular interactions, and exposed the internal hydrophobic regions. Pearson correlation analysis showed that sulfhydryl groups (r = 0.860), disulfide bonds (r = −0.875) and random coil (r = 0.917) were strongly correlated with the cholesterol-lowering activity of soy protein hydrolysate (SPH), following a simulated gastrointestinal digestion. Finally, the effects of HPU pretreatment on enzymolysis kinetics and thermodynamics of the SPI enzymatic process showed that HPU pretreatment significantly reduced the Mie's constant, activation energy, activation enthalpy, activation entropy and Gibbs free energy. Overall, the study outcome suggested that HPU pretreatment could positively influence the hypocholesterolemic peptide activity, and thus, may be beneficial to the pharmaceutical/food industry.

Influence of varying oil phase volume fractions on the characteristics of flaxseed-derived diglyceride-based Pickering emulsions stabilized by modified soy protein isolate

This research aimed to create Pickering emulsions using modified soy protein isolate (SPI) as a stabilizer and flaxseed-derived diglyceride (DAG) as an oil phase. The SPI was modified through a process involving both heating and ultrasound treatment. The result indicated that the droplet size of emulsions increased with the increase in oil content (p < 0.05). For instance, the largest droplet size (23 µm) was observed at an oil-to-SPI dispersion ratio of 4:1 ratio (φ = 80), whereas the smallest droplet size (6.39 µm) was noticed at the 1:4 ratio. During the 7-day storage period, the emulsions with a 4:1 ratio (φ = 80) showed the lowest droplet size increase (from 23 µm to 25.58 µm). In contrast, the emulsions with a 1:1 ratio displayed the highest increase (from 19.39 µm to 74.29 µm). Creaming index results revealed that emulsions with a 4:1 ratio (φ = 80) showed no signs of creaming and phase separation than all other treatments (p < 0.05). Backscattering fluctuations (ΔBS) and turbiscan stability index (TSI) showed that emulsions with 4:1, 2:1, and 1:1 oil-to-SPI dispersion ratios had consistent ΔBS curves with higher and TSI curves with lower values. Optical microscopy, confocal laser scanning, and cryo-scanning electron microscopy revealed that emulsions with oil-to-SPI dispersion ratios of 4:1 and 2:1 had well-organized structures with no visible coalescence. Macromorphological and microrheological investigations demonstrated that emulsions with 80% oil content had the highest viscosity, both moduli, elasticity index, macroscopic viscosity index, and the lowest fluidity index and solid–liquid balance values. Moreover, these emulsions were more resistant to centrifugation and storage environments. In conclusion, the study determined that flaxseed-derived DAG-based high internal phase Pickering emulsions (φ = 80) had superior stability, improved viscoelasticity, and better rheological properties.

Freeze-thaw stability of Pickering emulsion stabilized by modified soy protein particles and its application in plant-based ice cream

Pickering emulsions are of great interest to the food industry and their freeze-thaw stability important when used in frozen foods. Particles of soybean isolate (SPI) were heat treated and then crosslinked with transglutaminase (TG) enzyme to produce Pickering emulsions. The protein particles produced using unheated and uncrosslinked SPI (NSPI) was used as the benchmark. The mean particle size, absolute zeta potential, and surface hydrophobicity of protein particles produced using heat treatment and TG crosslinking (at 40 U/g) SPI (HSPI-TG-40) were the highest and substantially higher than those produced using NSPI. The thermal treatment of protein particles followed by crosslinking with TG enzyme improved the freeze-thaw stability of Pickering emulsions stabilized by them. The Pickering emulsions produced using HSPI-TG-40 had the lowest temperature for ice crystal formation and they had better freeze-thaw stability. The plant-based ice cream prepared by HSPI-TG-40 particle-stabilized Pickering emulsions had suitable texture and freeze-thaw stability compared to the ice cream produced using NSPI. The Pickering particles produced using heat treatment of SPI followed by crosslinking with TG (at 40 U/g) produced the most freeze-thaw stable Pickering emulsions. These Pickering particles and Pickering emulsions could be used in frozen foods such as ice cream.

Development and characteristics of emulsion gels with microwave-assisted ferulic acid covalently modified soy protein: Structure, function and digestive properties

This work aims to investigate the effect of microwave-assisted ferulic acid (FA) covalently modified soy protein isolate (SPI), which acts as a stabilizer, upon the structural and functional properties of emulsion gel. The results showed that the microwave and FA covalently modified SPI could synergistically strengthen the colloidal properties of the system and improve its structure. The microwave-assisted FA covalently modified SPI maximized the absolute value of the ζ-potential (−33.5 ± 2.1 mV) and the thermal denaturation temperature (152.3 °C) of the system. In addition, the smaller system particle size (115.3 ± 3.3 nm) and the increase in irregular structure allowed the generation of stronger gel-like network structures in stable emulsion gel. The enhancement of uniform oil-water distribution and stability was also confirmed by LF-NMR and microstructure. The results of gastrointestinal digestion experiments showed that quercetin loaded on emulsion gels stabilized by SPI-FA-M promoted lipid hydrolysis and improved the bioaccessibility (from 20.0 ± 2.1% to 37.2 ± 1.5%) and stability (from 39.7 ± 1.3% to 78.3 ± 4.5%) of quercetin. Our findings provide a new perspective for understanding the potential applications of combined physical-chemical modified proteins as emulsion gels stabilizers in food delivery systems.

Fabrication of nanoemulsion stabilized by high-pressure modified soy protein isolate-genistein for the encapsulation of lutein

In this study, we evaluated the interaction between high-pressure homogenization modified soybean isolate protein (HSPI) and genistein (GE), and constructed nanoemulsions for the co-encapsulated of GE and lutein using HSPI-GE as emulsifier. SPI formed complexes with GE mainly through hydrophobic interactions, and high-pressure homogenization treatment improved the interaction between SPI and GE. When the homogenization pressure was 120 MPa, the emulsification activity and emulsion stability indexes of HSPI-GE reached 196.71 m2g-1 and 237.98min, and the zeta potential of HSPI-GE nanoemulsion was −34.15 mV. Additionally, the encapsulation efficiency of HSPI-GE nanoemulsion was up to 93.88% and its storage stability was up to 66.01% after 20 d of storage. The HSPI-GE nanoemulsions achieved slow release of co-encapsulated GE and lutein and improved their bioaccessibility to 74.47% and 80.46% in in vitro simulated digestion. This work provides a theoretical basis for further studies on the application of HSPI-GE in lutein delivery systems.

Ферментативный гидролиз соевого белка

Soy continues to be one of the top sources of vegetable protein. Structurally modified soy proteins and processed products are used as part of functional foods. Enzymatic hydrolysates of food proteins have different degrees of hydrolysis and functional profiles, hence the constant search for the optimal hydrolysis parameters. The present research objective was to design a two-stage enzymatic conversion process of soy protein using mathematical methods, as well as to evaluate the antioxidant properties of the hydrolysate in laboratory conditions.&#x0D; Soy protein isolate was tested to define the maximal value of the hydrolysis degree. It underwent a series of two-factor experiments in the presence of pepsin and trypsin. The study focused on the hydrolysis time and the enzyme-substrate ratio. The results were optimized using the response surface methodology in MathCad 15. The total antioxidant activity of the hydrolysate during hydrolysis was determined on a Tsvet-Yauza-01-AA chromatograph using the amperometric method.&#x0D; For the pepsin test, the processing time was 7 h and the enzyme-to-substrate ratio was 1:22. For the trypsin test, the time was 7 h and the ratio was 1:30. The mathematical modeling revealed the following optimal parameters. The first stage involved hydrolysis with pepsin for 5 h at an enzyme-to-substrate ratio of 1:20; the second stage involved hydrolysis with trypsin for 3 h at an enzyme-to-substrate ratio of 1:19. The resulting hydrolysate demonstrated 88% hydrolysis. The highest summary antioxidant activity was registered after 5 h of hydrolysis and amounted to about 250 mg/100 mL.&#x0D; The resulting enzymatic hydrolysate of soy protein can be used as a food component or an antioxidant feed additive. The obtained peptides can immobilize essential microelements, e.g., Zn, I, and Se, as well as produce polyvalent complexes. Further studies will be aimed at the residual antigenicity of the hydrolysate and other functional indicators.

Construction of high internal phase Pickering emulsions using cold plasma modified soy protein isolate-proanthocyanidin complex

Protein-based high internal phase Pickering emulsions (HIPPEs) feature numerous multi-functionalities and widespread applications. However, the direct use of native proteins for the constructions of HIPPEs is limited since it is fragile under various conditions. Here, cold plasma was used to modify soy protein isolates (SPI) to improve their surficial properties. Meanwhile, proanthocyanidins (PA) were applied to interact with cold plasma-treated SPI to form complex. Furthermore, the well-prepared SPI-PA complex was used to construct novel HIPPEs. Results showed cold plasma treatment significantly improved the functionalities of SPI, which were confirmed by surface hydrophobicity (H0 ＜ 500), sulfhydryl (SH) groups and spectral analysis. Further, the emulsification and oxidation resistance of cold plasma treated SPI were enhanced after forming complex with PA. Soybean oils can be stabilized by SPI-PA complexes to form HIPPEs with a lipid oxidation inhibition rate of ＞ 65%, creaming index (CI) ＞ 80%, excellent rheological properties and better stability compared with conventional emulsion systems. Overall, this SPI-PA complexes provides a unique approach to improve the emulsification and oxidation resistance to engineer HIPPEs with versatile applications.

Performance Evaluation of an Improved ANFIS Approach Using Different Algorithms to Predict the Bonding Strength of Glulam Adhered by Modified Soy Protein–MUF Resin Adhesive

Despite studies on the potential replacement of synthetic resins by bio-based adhesives such as proteins in recent years, there is still no reliable method for estimating the strength of wood products made using the combined parameters in the literature. This limitation is due to the nonlinear relationship between strength and the combined components. In the present research, the application of artificial intelligence techniques was studied to predict the bonding strength of glulam adhered by protein containing different ratios of MUF (melamine–urea–formaldehyde) resin with different F-to-U/M molar ratios at different press temperatures. For this purpose, the ANFIS artificial intelligence model was used as basic mode or combined with ant colony optimization (ACOR), particle swarm optimization (PSO), differential evaluation (DE) and genetic algorithms (GA) to develop an optimal trained model to predict the bonding strength of glulam based on experimental results. Comparison of the obtained results with the experimental results showed the ability of the above methods to estimate the bonding strength of glulam in a reliable manner. Although the basic ANFIS alone and in combination with other algorithms was not able to achieve an ideal performance prediction to estimate bonding strength, the combination of GA and ANFIS offered an excellent ability compared to the combination of other algorithms combined with ANFIS. Hence, the developed ANFIS-GA model is introduced as the best prediction technique to solve bonding strength problems of laminated products. In addition, using the developed optimal model, a precise attempt was made to show the nature of the parameters used to produce glulam and determine the optimum limit.

Effect of sodium trimetaphosphate on the physicochemical properties of modified soy protein isolates and its lutein‐loaded emulsion

Due to people's pursuit of healthy and green life, soy protein isolate (SPI) is occupying a larger and larger market share. However, the low solubility of SPI affects its development in the field of food and medicine. This paper aimed to investigate the effects of sodium trimetaphosphate (STMP) on the functional properties and structures of phosphorylated SPI and its lutein-loaded emulsion. After modification by STMP, the phosphorus content of phosphorylated SPI reached 1.2-3.61mg/g. Infrared spectrum and X-ray photoelectron spectrum analysis confirmed that PO4 3- had phosphorylation with -OH in serine of SPI molecule. X-ray diffraction analysis showed that phosphorylation destroyed the crystal structure of protein molecules. Zeta potential value of phosphorylated SPI decreased significantly. When STMP addition was 100g/kg, particle size of protein solution decreased to 203nm, and solubility increased to 73.5%. Furthermore, emulsifying activity and emulsifying stability increased by 0.51 times and 8 times, respectively. At the same protein concentration (1%-3% [w/w]), lutein-loaded emulsion prepared by phosphorylated SPI had higher absolute potential and smaller particle size. The phosphorylated protein emulsion at 2% concentration had the best emulsion stability after storage for 17days. PRACTICAL APPLICATION: Phosphorylation significantly improved the emulsifying properties and solubility of SPI. Phosphorylated SPI significantly improved the stability of lutein-loaded emulsion. It provides theoretical basis for the application of phosphorylated SPI as emulsifier in delivery system and broadens the development of lutein in food and medicine field.

Standardized ileal digestible amino acids and digestible energy contents in two modified soy protein concentrates and soybean meal fed to growing pigs.

Six ileal-cannulated barrows (28.0 ± 1.3 kg initial BW) were used in a replicated 3 × 3 Latin square design with one additional period (n = 7 or 6) to determine standardized ileal digestible (SID) AA and digestible energy of two modified soy protein concentrates [MSPC1 and MSPC2] and soybean meal (SBM). Pigs were fed one of three cornstarch-based diets with either MSPC1 or MSPC2 or SBM as the sole source of AA at a rate of 2.8 times the estimated maintenance energy requirement. In each period, pigs were adapted to diets for 7 d followed by 2 d of fecal collection and subsequently, 2 d of continuous ileal digesta collection for 8 h. The SID of AA was calculated using basal endogenous losses from a previous study for pigs fed a nitrogen-free diet. The digestible energy of the ingredients was calculated according to the difference method using a nitrogen-free diet that contained the same cornstarch:sucrose:oil ratio as the three test diets. The total Lys content was 33% and 38% greater for MSPC1 vs. MSPC2 and SBM, respectively. The SID of crude protein was greater for MSPC1 (96.9%) than for SBM (91.3%; P < 0.05), whereas an intermediate value was observed for MSPC2 (94.3% ± 1.2%). The SID of Ile (93.8%), Leu (93.6%), Lys (93.9%), Phe (96.7%), and Val (93.2%) were not different between MSPC1 and MSPC2 but greater than for SBM (88.8% ± 1.3%, 87.8% ± 1.2%, 84.5% ± 1.7%, 92.9% ± 1.0%, 86.5% ± 1.7% for Ile, Leu, Lys, Phe, and Val, respectively; P < 0.05). The SID of His and Thr was greater for MSPC1 than MSPC2 and SBM (P < 0.05), which were not different. The SID of Met was greater for MSPC1 and SBM vs. MSPC2 (P < 0.05). The SID of Arg was greater for MSPC1 than MSPC2 and SBM (P < 0.05), and greater for MSPC2 than SBM (P < 0.05). The digestible energy was greater for MSPC1 (4,677 kcal/kg) than MSPC2 and SBM (average; 3,896 ± 239 kcal/kg; P < 0.05), which were not different. Therefore, the MSPC1 was a better source of SID Lys and digestible energy than either MSPC2 or SBM and could be used as a highly digestible protein ingredient in swine rations.

Gel Property of Soy Protein Emulsion Gel: Impact of Combined Microwave Pretreatment and Covalent Binding of Polyphenols by Alkaline Method.

This study investigated the effects of microwave modification, alkali polyphenol (ferulic acid) covalently combined modification, and microwave-alkali polyphenol covalently combined modification on the gel properties of soy protein emulsions. The results showed that the properties of soy protein emulsions were improved significantly by the three modification methods. After three kinds of modification, the viscoelasticity of soy protein emulsion gel increased, and a gel system with stronger elasticity was formed. The texture, water-holding, and hydration properties of the emulsion gel increased significantly. The SEM and ClSM results showed that the modified soy protein emulsion gel had a more compact and uniform porous structure, and the oil droplets could be better embedded in the network structure of the gel. Among the three modification methods, the microwave-alkali method polyphenol covalently combining the compound modification effect was best, and the microwave modification effect was least effective compared to the other two methods. Our obtained results suggested that for gel property modification of soy protein emulsion gels, microwave pretreatment combined with the covalent binding of polyphenols by an alkaline method is an effective method.