Soy Protein Isolate Concentration Research Articles

Fabrication of ultrafine Himalayan walnut oil Pickering emulsions by ultrasonic emulsification: Techno-functional properties of emulsions and microcapsules

In present scenario, much of the attention has been put on the production and utilization of Pickering emulsions deciphering enhanced stability and applicability over wide environmental conditions. In this context the present study was carried out to elaborate effect of different wall materials and pH systems on the physicochemical, structural and morphological properties of Himalayan walnut oil Pickering emulsions by ultrasonic emulsification. In this study, concentrated Pickering emulsion of Himalayan walnut oil (HWO) was prepared utilizing soy protein isolate (SPI), maltodextrin (MD) stabilized by pectin at varying concentrations and pH systems (4.0, 7.0). With increase in pectin and SPI concentration and lowering MD, stable emulsions were obtained as deciphered by an Emulsion stability index (ESI) of 100 for 7 days at ambient storage. HWO Pickering emulsions were analysed for particle size measurements (2.13–13.64 µm) and depicted negative zeta potential values (−3.70 to −18.58). Lyophilized HWO microcapsules depicted moderate encapsulation efficiency (44.69–57.63 %) whereas the hygroscopicity values of the microcapsule ranged from (0.21–12.10 %). Thermogravimetric analysis (TGA) of the samples depicted the temperature of maximum degradation rate up to 550 °C whereas XRD spectra depicted amorphous nature of oil microcapsules. FTIR spectra revealed a close association between the SPI-MD-Pectin matrix. SEM analysis revealed stable oil globules entrapped in protein-polysaccharide matrix with no visible cracks and fissures.

The Preparation of W/O/W High-Internal-Phase Emulsions as Coagulants for Tofu: The Effect of the Addition of Soy Protein Isolate in the Internal Water Phase.

Tofu quality is determined by a controlled coagulation process using a W/O/W emulsion coagulant. The impact of adding soy protein isolate (SPI) to the inner water phase on the stability of W/O/W high-internal-phase emulsions (HIPEs) and its application as a coagulant for tofu was assessed. No creaming occurred during 7-day storage with SPI concentrations up to 0.3%, while the emulsion droplets aggregated with 0.5% and 0.7% SPI. Emulsions containing 0.3% SPI maintained a constant mean droplet size after 21 days of storage and exhibited the lowest TURBISCAN stability index value. HIPE stability against freeze-thaw cycles improved after heating. HIPEs with SPI concentrations above 0.3% demonstrated an elastic gel-like behavior. The increased viscosity and aggregation of the protein around droplets indicated that the interaction among emulsion droplets could enhance stability. W/O/W HIPE coagulants significantly increased tofu yield, reduced hardness, and produced a more homogenous tofu gel compared to a MgCl2 solution. The HIPE with 0.3% SPI was found to be optimal for use as a coagulant for tofu.

Phase inversion of bigels tuned by the concentration of soy protein isolate in the binary hydrogel matrix

Phase inversion of bigels is typically achieved by controlling the oleogel/hydrogel (OG/HG) ratio in previous studies. In this study, a binary hydrogel consisting of different concentrations of soy protein isolate (SPI) to konjac glucomannan (KGM) was designed to fabricate bigels with ethyl cellulose (EC) oleogel at a fixed mass ratio of oleogel to hydrogel (OG:HG), and the phase inversion was subsequently achieved by increasing the concentration of SPI in the binary hydrogel, resulting in a transition from W/O to O/W bigels and then back to W/O bigels. Specifically, when the binary hydrogel contained 1 wt% SPI and 0.5 wt% KGM, the bigel type was O/W. A KGM network existed between the oil droplets of O/W bigels and within the internal phase of W/O bigels, with SPI being adsorbed at the oil-water interfaces of the bigels. As the concentration of SPI increased, the oil-water interfaces became progressively populated with proteins, leading to an increment in droplet diameter and a reduction in hardness, as well as an elevation of free water content within the bigels. This study proposes a novel operational strategy for controlling the phase inversion of bigels and developing encapsulation delivery systems by adjusting the concentration of SPI in binary hydrogels.

Development and optimization of oleogel made with soy protein isolate and xanthan gum using emulsion template approach and its comparison with solid fats

This study aims to develop oleogel as a potential substitute for solid fats in the diet. A novel combination of unmodified Soy Protein Isolate (SPI) and Xanthan Gum (XG) have been utilized to gelate sunflower oil, using an emulsion template approach. The experimental trials employing Response Surface Methodology are conducted to optimize various parameters that affect the oil binding capacity, textural and rheological properties of the oleogel. The concentration of soy protein varies in the range of 5–15 %, the ratio of soy protein to xanthan gum ranges from 1:2 to 1:4, and the ionic strength varies from 0.2 to 1 M. The goal is to formulate oleogel that closely resembles solid fats. Responses namely the oil binding capacity and gel strength value of oleogel were observed best fitted to a linear model whereas, the hardness of oleogel found following a quadratic model. The SPI-XG combination was found effective in entraping more than 95 % of the oil. The best formulation of SPI: XG, 1:4; SPI concentration, 15 % and ionic strength of 1.0 M with 95.5 % of oil retention and hardness and gel strength value comparable to commercial solid fats.

Physicochemical properties and stability of oil-in-water emulsions stabilized by soy protein isolate and xanthan gum

The aim of this work was to determine rheological and disperse characteristics and stability of oil-in-water emulsions stabilized by soy protein isolate (SPI) and xanthan gum (XG), as natural components. The effects of their combination on emulsion stabilization have not been investigated yet. The existence of interactions between the two macromolecules were indicated by the influence of XG on SPI surface hydrophobicity and surface tension values. Increase in SPI concentration from 1 to 3 % shift of distribution curves towards smaller particle size, while the opposite effects of further increase of SPI was obtained. The emulsions stabilized by SPI showed shear-thinning flow behavior, which changed to thixotropic at 5 % of SPI concentration. The presence of XG in emulsions at low concentrations did not affect the size distribution of the droplets, while at 0.1 % of XG Sauter mean diameter value raised and distribution curves were shifted towards a higher particle size. The presence of XG at higher concentration resulted in thixotropic flow behavior of emulsions. Also, increase in XG concentration led to the increase in consistency index and extent of non-Newtonian behavior of emulsions and enhanced the influence of the elastic modulus and creaming stability of the systems.

Parameter control, characterization and stability of soy protein emulsion prepared by microfluidic technology.

A flow-focusing microfluidic device driven by pressure was employed in soy protein emulsions with uniform droplet size and good morphology. The results suggested that pressure was an essential factor for droplet formation. The optimum parameter was at a continuous phase pressure of 140mbar and dispersed phase pressure of 80mbar. Under this condition, the droplet formation time was shortened to 0.20s, with average sizes of 39-43μm and coefficient of variation of about 2%. Emulsion stability was improved with increasing soy protein isolate (SPI) concentrations. At SPI concentrations higher than 20mg/mL, the emulsions exhibited improved stability against changes in temperature, pH and salt concentration. Emulsions prepared in this manner exhibited superior oxidative stability than those prepared by conventional methods utilizing homogenizers. This study showed that microfluidic technology can be applied to soy protein emulsions as an effective tool for preparing droplets with uniform size and enhanced stability.

Soy Protein Nanofibers Obtained by Solution Blow Spinning

The climate crisis, growing pollution of the environment with waste, and ubiquitous microplastics have encouraged the search for new methods and new opportunities to use natural materials in the least harmful processes. Replacing synthetic materials with raw materials is not only a matter of “fashion”, but also a necessity. Therefore, this study aimed to produce fibers from an aqueous solution containing the highest possible concentration of soy protein isolate (SPI) through solution-blowing. As the aqueous solution of SPI has no fiber-forming potential, polyethylene oxide (PEO) was used as the carrier/matrix. The rheology of the aqueous PEO solution and PEO/SPI blends (flow curves, loss modulus, and storage modulus) was then analyzed. The proportions of the PEO/SPI mixtures and the process parameters were determined on this basis. As a result of the conducted research, nanofibers were produced from water solutions of PEO/SPI with a soy protein content of up to 7.88%, with a PEO share of 1.25%. The average diameter of the obtained fibers was 225–495 nm, depending on the process parameters and SPI content—as the SPI content in the PEO/SPI mixture increased, the average fiber diameter decreased. The production of nanofibers with a high soy protein content increases their application possibilities. Firstly, due to a much larger surface area, and secondly, due to the presence of numerous functional groups in the protein structure, which can be a place of attachment for additional compounds that give the obtained nanofibers the desired properties.

Optimizing foam quality characteristics of model food using Taguchi‐based fuzzy logic method

AbstractIn this study, the effects of soy protein isolate (SPI) concentration (0%, 50%, and 100%), sonication time (10, 20, and 30 min), and whipping time (5, 10, and 15 min) on the quality characteristics of the model food foam were investigated and optimized. In order to maximize both foaming capacity (FC) and foam stability (FS), it was aimed to select the optimum process parameters using a Taguchi‐based fuzzy logic method (TBFLM). The experiments were performed according to Taguchi L9 (33) orthogonal design, and the effects of process parameters on foam quality characteristics were investigated by analysis of variance. Optimization results revealed that optimum FC and FS values were obtained with 50% SPI, 30 min sonication, and 10 min whipping. SPI concentration was the most effective factor for the responses in Taguchi single‐response optimization. However, the whipping time has the greatest impact on the multiperformance characteristics index, accounting for 78.93% of the contribution to fuzzy logic multiresponse optimization. The verification experiments revealed that the TBFLM is a useful method for improving foam quality characteristics.Practical applicationsFC and FS are the most important properties, which represent the quality characteristics of model food foams. The Taguchi method failed in multiresponse optimization in the model food application. A Taguchi‐based Fuzzy logic optimization method was successfully applied to optimize the quality characteristics of model food foam, and the optimal conditions were determined as soy protein isolate of 50%, sonication time of 30 min, and whipping time of 10 min. The contribution of whipping time to the multiperformance characteristics index was found to be the highest.

Effect of soy protein isolate concentration and whipping time on physicochemical and functional properties of strawberry powder

The objective of this work was to study the effect of soy protein isolate concentration (0.5–9%) and whipping time (1–8 min) on foam characteristics, physicochemical and functional properties of hot air foam-mat-dried strawberry powder. An optimization of foaming conditions was performed by response surface methodology to maintain the studied responses within acceptable limits. The foam was prepared using different concentrations of soy protein isolate solution (32%) and dried at 50 °C in a thin layer (4 mm as a thickness). The concentration of soy protein was the predominant parameter affecting foam density, expansion, and stability, and physicochemical and functional properties of strawberry powder. Total phenolic content, total flavonoid content, antioxidant activity, water holding capacity, and oil holding capacity increased by about 26, 47, 166, 21, and 48%, respectively, with an increase in the concentration of soy protein isolate, compared to the control sample. Contrary, the whipping time showed a contradicted effect on all studied responses except the foam expansion and oil holding capacity.

Phytosterols photooxidation in O/W emulsion: Influence of emulsifier composition and interfacial properties

Although phytosterols (PS) showed various excellent health functions, their applications in the food industry were limited by poor water solubility and high oxidation sensitivity. This study investigated the fabrication of phytosterol-enriched emulsions stabilized by different emulsifiers and evaluated the effect of different interfacial layers on the photooxidation of phytosterols and emulsions. The emulsions were prepared with Tween 20, whey protein isolate (WPI), and soy protein isolate (SPI) to achieve interfacial membranes with different properties. The SPI-dextran mixture or dextran-glycated SPI was adopted as the additional emulsifier. Compared with Tween 20, high molecular weight emulsifiers (proteins and their mixtures) exhibited stronger photooxidation stabilities and high viscosity and density of droplet interfacial membrane. The stability of PS emulsions that undergo photooxidation was impacted by the inclusion of these emulsifiers, whereas the extent of phytosterols photooxidation was, from highest to lowest, in the following order: SPI/dextran mixture > glycated SPI mixture > WPI > SPI > Tween 20. The proper SPI concentration (1.5 wt%) showed the highest interface pressure and viscosity and the higher PS stability. Moreover, the higher rheological properties and surface pressure of droplets reveal extra oxidative stability and lower oxidation rate of PS, as well as the formation of additional 7β-OH products. This work demonstrates that emulsions may be tuned toward better photooxidation oxidative stability by modifying interface composition and interfacial properties.

Soy Protein Isolate as Emulsifier of Nanoemulsified Beverages: Rheological and Physical Evaluation.

The production of biologically active molecules or the addition of new bioactive ingredients in foods, thereby producing functional foods, has been improved with nanoemulsion technology. In this sense, the aim of this work was to develop nanoemulsified beverages as potential candidates for the encapsulation of bioactive compounds, whose integrity and release across the intestinal tract are controlled by the structure and stability of the interfaces. To achieve this, firstly, a by-product rich-in protein has been evaluated as a potential candidate to act as an emulsifier (chemical content, amino acid composition, solubility, ζ-potential and surface tension were evaluated). Later, emulsions with different soy protein isolate concentrations (0.5, 1.0, 1.5 and 2.0 wt%), pH values (2, 4, 6 and 8) and homogenization pressures (100, 120 and 140 PSI) were prepared using a high-pressure homogenizer after a pre-emulsion formation. Physical (stability via Backscattering and drop size evolution) and rheological (including interfacial analysis) characterizations of emulsions were carried out to characterize their potential as delivery emulsion systems. According to the results obtained, the nanoemulsions showed the best stability when the protein concentration was 2.0 wt%, pH 2.0 and 120 PSI was applied as homogenization pressure.

Producing mixed-soy protein adsorption layers on alginate microgels to controlled-release β-carotene

In this study, the effects of soy protein isolate (SPI) on the morphology, encapsulation efficiency, storage stability, swelling behavior, and in vitro digestion behavior of calcium alginate (CA) microgels were investigated. CA and calcium alginate-SPI (CAS) microgels with encapsulated β-carotene were prepared by extruding a mixture of alginate and SPI using a co-extrusion technique, followed by cross-linking with Ca2+. All microgels exhibited homogeneous sizes and spherical shapes, and CAS microgels showed high levels of protein loading efficiency. The encapsulation efficiency and storage stability of β-carotene within CAS microgels were higher than those within CA microgels. The introduction of SPI into CAS microgels resulted in a higher degree of gel size shrinkage in gastric fluid and a lower degree of swelling in intestinal fluid compared to CA microgels. In vitro digestion was conducted to investigate the effects of the addition of SPI on the release behavior of CA and CAS microgels. Results obtained showed that CAS microgels were more resistant to simulated gastric fluid than CA microgels. Cryo-scanning electron microscopy (cryo-SEM) and confocal laser scanning microscopy (CLSM) observations indicated that the release behavior was dependent on the porosity of the CA and CAS microgels, and the porosity was influenced by the concentration of SPI. This study showed that the introduction of SPI to CA microgels can lead to the development of an effective controlled release delivery system.

Efficient binding paradigm of protein and polysaccharide: Preparation of isolated soy protein-chitosan quaternary ammonium salt complex system and exploration of its emulsification potential

Soy protein isolate (SPI) has good emulsifying ability, but is greatly affected by the environment. The addition of polysaccharides either increases or decreases the stability of SPI. We report and prepared for the first time SPI/HACC complexes with different polysaccharide contents (SPI/HACC ratios are 1:1, 2:1 and 5:1). The binding properties, microstructure and emulsifying properties of the SPI/HACC complexes were determined and analyzed. The results showed that the interaction them is mainly through hydrogen bonding, electrostatic interaction, hydrophobic interaction and steric hindrance effect. The combination of SPI and HACC overcomes their respective limitations and the microstructure is more flat and smooth. It was also found that the emulsifying ability and concentration of SPI showed a certain correlation and the addition of HACC significantly improved the emulsifying ability and storage stability of SPI. This study shows that the prepared SPI/HACC complex has great potential for application in the food industry.

Effect of foaming parameters on the physical and phytochemical properties of tomato powder

The objective of this work was to study the effect of foaming parameters on the physical and phytochemical properties of tomato powder. A central composite rotatable design of experiments was defined with two parameters (concentration of soy protein isolate [SPI]: 1–5% and whipping time: 2–14 min) with 5 levels for each parameter. The foam was prepared by whipping tomato puree after adding SPI and dried in a thin layer (4 mm ± 1) at 50 °C. The obtained results showed the predominant effect of the concentration of SPI on the physical and phytochemical properties compared to whipping time. The powder prepared under foaming conditions of 5% SPI and whipping time of 8 min showed an increase of 97, 39, 62, and 46% in the total phenolics, total flavonoids, antioxidant activity, and porosity, respectively, while the bulk density decreased by about 25%.

Freeze-Thaw-Induced Physically Cross-linked Superabsorbent Polyvinyl Alcohol/Soy Protein Isolate Hydrogels for Skin Wound Dressing: In Vitro and In Vivo Characterization.

In this work, polyvinyl alcohol (PVA)- and soy protein isolate (SPI)-based scaffolds were prepared by physical cross-linking using the freeze-thaw method. The PVA/SPI ratio was varied to examine the individual effects of the two constituents. The physicochemical properties of the fabricated scaffolds were analyzed through Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. The SPI concentration significantly affected the properties of scaffolds, such as the extent of gelation (%), pore size, porosity, degradation, swelling, and surface wettability. The in vitro degradation of fabricated hydrogels was evaluated in phosphate-buffered saline and lysozyme solution for a duration of 14 days. The in vitro compatibility of prepared hydrogels was evaluated by the MTT assay with NIH-3T3 cells (fibroblast). The water vapor transmission rate (WVTR) assays showed that all hydrogels possessed WVTR values in the range of 2000-2500 g m-2 day-1, which is generally recommended for ideal wound dressing. Overall, the obtained results reveal that the fabricated scaffolds have excellent biocompatibility, mechanical strength, porosity, stability, and degradation rate and thus carry enormous potential for tissue engineering applications. Furthermore, a full-thickness wound healing study performed in rats supported them as a promising wound dressing material.

Fish oil-in-water emulsions stabilized by soy proteins and cellulose nanocrystals

This work aimed to develop fish O/W emulsions using soy protein isolate (SPI) and cellulose nanocrystals (CNC) either as separate stabilising agents or in combination. The fish O/W emulsions were prepared using aqueous dispersions containing SPI and/or different concentrations of CNC at neutral pH. The effects of each component and their concentration on the microstructure, droplet size, zeta potential, rheological behaviour, and stability of the resulting emulsions during its quiescent storage at room temperature were analysed. Emulsions prepared with both SPI and CNC showed droplets with larger sizes and surface charge than those stabilized only by SPI and were more stable than those stabilized by each component separately. The concentration of CNC determined the physicochemical and rheological properties of SPI + CNC emulsions, as well as the intervening destabilization mechanisms. Emulsion stabilized by SPI + 0.1% CNC that had a high degree of initial flocculation, turned out to be the most stable during 15 days of quiescent storage at room temperature.

Emulsion-filled gels of soy protein isolate for vehiculation of vitamin D3: Effect of protein solubility on their mechanical and rheological characteristics

The aim of this study was to develop heat-induced gels of soy protein isolate (SPI) filled with Brazil nut oil emulsions encapsulating vitamin D3 (VD3). Before gelation, dispersions produced with different SPI concentrations (11–15%, w/w) were subjected to different pretreatments (manual mixing or mechanical stirring at 800 rpm for 10, 20, and 30 min) and had their protein solubility quantified. The application of mechanical stirring increased the solubility of proteins and decreased the average particle size, affecting the microstructure (observed by confocal laser scanning microscopy) and rheological properties (evaluated by uniaxial compression and small strain oscillatory tests) of the heat-set gels. The incorporation of emulsions (produced with Brazilian nut oil) into gels formed emulsion filled gels (EFGs), which presented higher Young's moduli and σH in comparison to non-filled gels (NFGs), indicating that the oil droplets were active within the matrices. The properties of EFGs subjected to small strain oscillatory tests, varied with the pretreatment conditions and SPI concentrations, highlighting the high influence of protein solubility, matrix inhomogeneities, and droplet clustering for determining the properties of such complex systems. Also, the heat-induced emulsion-filled gels of SPI produced were effective in protecting VD3, presenting good retention after 30 days of storage under refrigeration, and represent promising alternative for the production of future food gelled products.

Effect of different concentrations of sodium chloride and soy protein isolate with mono- and diglycerides/corn oil on physical properties and stability of w/o/w double emulsion

The successful fabrication of double emulsion is determined by the ingredients or the process. The aim of the study was to determine the effects of sodium chloride and soy protein isolate with addition of mono-and diglycerides/corn oil on physical and stability of emulsion. Model emulsions with different concentration of sodium chloride (0.5% and 1.5%) and soy protein isolate (1% and 3%) with addition of mono-and diglycerides/corn oil (ratio 1:1) were prepared. Physical properties and stability of double emulsion were characterized by viscosity, emulsion stability, pH, and color. The results showed that the stability of double emulsion was significantly affected (p < 0.05) by the interaction between sodium chloride and soy protein isolate, whereas pH and viscosity were affected only by the concentration of soy protein isolate. However, double emulsion containing 1.5% of sodium chloride and 3% of soy protein isolate (SPI) with addition of mono-and diglycerides/corn oil showed the highest stability in comparing with emulsion containing 0.5% of sodium chloride and 3% of SPI.

In vitro digestibility of rare sugar (D‐allulose) added pectin–soy protein gels

SummaryConfectionery gels are known to be high‐caloric products due their high sugar content. Changing their formulations by substituting the sugar with alternative natural sweeteners and functionalising them, the addition of proteins has gained attention. Understanding the rate of digestion of these products is also important for selecting the appropriate formulation. In this study, in vitro gastric digestion behaviour of the gels formulated with D‐allulose, a low‐calorie rare sugar, soy protein isolate (SPI) (1%, 2.5%) and pectin (4%) were examined. Digestion decreased the hardness of the gels (P &lt; 0.05), but, at 2.5% SPI concentration. Moisture content of the samples increased after digestion and presence of SPI induced higher water uptake. At the end of 2 h of digestion, 1% soy protein isolate containing gels had the highest brix values showing that after a certain concentration, soy protein isolate governed the system due to improved soy protein–pectin interaction or due to improved gelation with Maillard reaction. NMR relaxometry experiments further confirmed the changes in the gels with the increase in T2 values. Power law model was fitted for the dissolution behaviour using the oBrix values of the digestion medium. Dissolution of sugar and the contribution of SPI to the gel network were clearly observed in SEM images. Results showed that these gels had the potential to slow down the emptying rate of stomach thus could lead to ‘fullness’ for a longer time.

Double-Network Hydrogels of Corn Fiber Gum and Soy Protein Isolate: Effect of Biopolymer Constituents and pH Values on Textural Properties and Microstructures.

Corn fiber gum (CFG) -soy protein isolate (SPI) double-network (DN) hydrogels were fabricated using laccase and a heat treatment process, in which CFG solution formed the first gel network via laccase oxidation, while SPI formed the second network through heating, as described in our previous research. The aim of this study was to investigate the influences of CFG/SPI constituents (CFG concentration 0–3%, w/v; SPI concentration 8–10%, w/v) and pH values (5.0–7.5) on the textural properties, microstructures and water-holding capacities (WHC) of the CFG-SPI DN hydrogels. Confocal Laser Scanning Microscopy (CLSM) results showed an apparent phase separation when the CFG concentration was above 1% (w/v). The textural characteristics and WHC of most DN hydrogels were enhanced with increasing concentrations of CFG and SPI. Scanning Electron Microscopy (SEM) observations revealed that the microstructures of DN hydrogels were converted from coarse and irregular to smooth and ordered as pH values increased from 5.0 to 7.5. Excellent textural properties and WHC were observed at pH 7.0. This study developed various CFG-SPI DN hydrogels with diverse textures and structures, governed by the concentrations of protein/polysaccharide and pH values, and also contributes to the understanding of gum–protein interactions in DN hydrogels obtained under different conditions.