•The formation of soybean protein isolate (SPI) and anthocyanin (ANC) was studied.•SPI and ANC complexes were interacted by covalent and non-covalent interactions.•ANC showed a stronger interaction ...with SPI in the covalently linked complex.•The β-turn and random coil contents of SPI-anthocyanin complexes were increased.
The present study was aimed to evaluate the interaction between anthocyanins from black rice and soybean protein isolate (SPI) via non-covalent and covalent bindings and the impact of these interactions on the functional and conformational changes of soybean protein. The conformational changes of the protein structure with different concentrations of anthocyanins (0.05, 0.1%, and 0.2%) were analyzed using three-dimensional fluorescence and Fourier transform infrared spectroscopy. The anthocyanins were more likely to form covalent interactions with SPI instead of non-covalent interactions. The addition of anthocyanins changed the secondary structure of SPI with a decrease in β-sheets and an increase in β-turns and random coils. The emulsifying and foaming properties of SPI were improved after complexation with anthocyanins. This study might be useful for elucidating the mechanisms behind the binding of anthocyanins with SPI and the possible uses of SPI-anthocyanin complexes in food formulations.
Owing to the rapid growth of the world's population and the consequent effects on the consumption of natural resources, we are facing increasing shortages in availability of proteins with high ...biological value. Additionally, considerations relating to animal welfare and human health have promoted the development of plant protein meat alternatives. The market for plant-based meat alternatives is expanding rapidly to cater to growing consumer demand. Soy protein has been successfully utilized in the preparation of meat alternatives, due to its excellent gelation properties and potential to form fibrous structures, and has become the most widely known alternative to animal protein.
In this review, the development history of soy protein-based meat alternatives is summarized briefly. Next, the research work on raw material composition and main processing strategies of soy protein meat alternatives is highlighted, including protein and non-protein ingredients and extrusion processing techniques. Lastly, research prospects and development trends of soy protein meat alternatives are also outlined.
High moisture extrusion is a relatively mature technology and is widely used for manufacturing soy protein meat alternatives with a similar fiber texture to meat. The main raw materials for preparing soy protein meat alternatives are soy protein and wheat gluten, although there are also studies on the use of vegetable proteins such as pea protein and peanut protein. Besides the main protein components, the addition of starch, fiber and other excipients also have an important impact on the development of fiber structure and nutrient richness of soy protein meat alternatives. In the process of extrusion, the interaction between these components causes a series of physical and chemical changes to occur, and anisotropic fiber structures to form. Further research needs to focus on optimizing technical parameters, improving nutrition and safety, and enriching product taste to meet consumer demands for product quality.
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•The development history of soy protein-based meat alternatives is summarized.•The recent studies on soy meat alternatives are highlighted.•The flavor improvement of soy meat alternatives is also reviewed.•The research prospects of soy meat alternatives are also outlined.
High internal phase Pickering emulsions (HIPPEs) stabilized by food-grade particles have received much attention in recent years. However, the stabilizing mechanism (e.g., structural network) in the ...continuous phase of HIPPEs stabilized by proteins is not well understood. In this work, we deciphered the stabilizing mechanisms that confer stability to HIPPEs produced from sunflower oil and soy protein microgels (SPMs). HIPPEs were fabricated at the protein concentrations of 1.50-2.00 wt % and oil volume fraction of 0.78-0.82. The cryo-scanning electron microscopy (cryo-SEM) observations indicated that there were two possible stabilizing mechanisms for HIPPEs at the protein concentrations of 1.50-2.00 wt %: the first is a stabilization provided by the shared monolayer of SPMs (at a protein concentration of 1.50%), and the other is stabilization provided by the distinct monolayer of SPMs (at protein concentrations of 1.75 and 2.00 wt %). The latter protein concentration created a thick network, formed by interacting SPMs, which trapped oil droplets. Results also confirmed that HIPPEs have an open-cell porous structure, forming a sponge-like morphology, where the internal phase was located. This study also investigated the digestibility of HIPPEs, suggesting a slower free fatty acid-releasing profile in
intestinal digestion.
Soy proteins are a good source of essential amino acids, whereas anthocyanins are known to possess significant beneficial biological activity, such as anti-inflammatory, and antioxidative properties. ...In combination, these two groups of compounds could be an excellent source on the utilization of nutrients in supplemental sources. The present work describes the feasibility of using soy protein isolate (SPI) and anthocyanins (ACN) to fabricate a novel Pickering emulsion stabilized by SPI-ACN complex nanoparticles. SPI and ACN were covalently bonded in the nanoparticles. The properties of the nanoparticles were investigated using particle size, zeta-potential, surface hydrophobicity, and antioxidant capacity analyses. The emulsion stability, oxidative stability, in vitro gastrointestinal digestive behavior, and microstructure of the fabricated Pickering emulsion were also characterized. Results indicated that the Pickering emulsion exhibits unique characteristics, including extraordinary emulsion stability, improved oxidative stability, and resistance to in vitro digestion. These findings would be of importance in the designing of Pickering emulsions stabilized by protein-polyphenol nanoparticles with aims of simultaneously delivering nutrients associated with health benefits.
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•Soy protein isolate (SPI) and anthocyanin (ACN) are used to fabricate nanoparticles.•A Pickering emulsion stabilized by SPI-ACN nanoparticles was successfully created.•The emulsion exhibits a great potential to improve lipid oxidation stability.•The emulsion simultaneously delivers polyphenols with associated health benefits.
The skim fraction (SF) obtained from enzyme‐assisted aqueous extraction (EAE) of soybeans is a by‐product with high protein content of up to 60.67%. As such, it is of great interest to develop an ...efficient method to recover protein from this fraction. In this study, the potential of dead‐end ultrafiltration (UF) in recovering skim protein extracted with different proteases was evaluated. Two polyethersulfone (PES) membranes with molecular weight cutoffs (MWCO) of 3 kDa and 5 kDa were utilized. Results revealed that the membrane with the MWCO of 5 kDa exhibited better filtration efficiency, since higher permeate flux values and lower impurity rejections were observed. Compared with Flavourzyme and Protex 7L, Alcalase 2.4L and Protex 6L exhibited stronger hydrolyzing ability, resulting in higher filtration fluxes but lower protein rejection coefficients. The recovered protein showed comparable amino acid profile to SPC, while with significantly reduced levels of trypsin inhibitors and phytate (p < 0.05), indicating high quality of the recovered protein. Overall, UF can be applicable to recover high value‐added protein from EAE of soybeans and remove undesired components from the resulting protein products.
Ultrafiltration can be applicable to recover high value‐added protein from enzyme‐assisted aqueous extraction of soybeans and remove undesired components from the resulting protein products. The recovered protein had comparable amino acid profile to soybean protein concentrate, while consisted of significantly decreased levels of trypsin inhibitors and phytate (p < 0.05), indicating high quality of the recovered protein.
The complexation of anthocyanin-rich black rice extracts (ARBRE) with soybean protein isolate (SPI) heated at 0, 70, 85, and 100 °C and its effect on protein digestibility were studied. The ...structural changes of SPI during its interaction with ARBRE in all the samples were studied by Fourier transform infrared, circular dichroism, and fluorescence spectroscopy. The secondary structure changes of SPI in all the samples after complexation with ARBRE showed a significant increase in α-helix and a significant decrease in β-sheet contents. Results also showed that ARBRE quenched the SPI fluorescence (in both unheated and heated samples) via static quenching with a single binding site. The digestibility of unheated and heated SPI was improved upon complexing with ARBRE. The formation of the SPI-ARBRE complexes is beneficial for the application of soy protein-based products in foods by increasing their protein digestibility and nutritional quality.
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•ARBRE altered the secondary structure of SPI with an increase in α-helix and decrease in β-sheet contents.•ARBRE altered the secondary structure of the SPI mainly via hydrogen bond.•The binding of heat treated SPI and ARBRE was higher at higher temperature.•The complexation of SPI with ARBRE improves the digestibility of SPI.
Chitin nanocrystals (ChNs) were successfully fabricated from shrimp and their effects on the microstructure and gelling properties of glucono-δ-lactone-induced soy protein isolate (SPI) were ...investigated. Firstly, transmission electron microscopy (TEM) showed that the average length and width of ChNs were 208.8 nm and 19.2 nm, respectively. The zeta potentials of ChNs changed from +38.6 mV at pH 3.0 to +16.4 mV at pH 8.0. Subsequently, the gel strength, water holding capacity (WHC) and viscoelasticity of the composite gels were improved by increasing the ChNs concentration from 0 to 1.0% (w/v). Based on low field nuclear magnetic resonance (LF-NMR) analysis, the decrease in PT22 and increase in PT21 indicated that the improvement of WHC was associated with the transformation of free water into immobilized water. Scanning electron microscopy (SEM) showed that the incorporation of ChNs promoted the formation of a denser and more homogenous gel network. All composite gels showed high frequency dependence and a typical Type I (strain thinning) network behavior. The increase in both elastic and viscous moduli further showed the improvement in the microstructure of composite gels, which was induced by the addition of ChNs. The Sequence of Physical Processes (SPP) analysis provided a detailed deformation history of gel microstructure by the evolution of the instantaneous storage (G′t) and loss moduli (G″t). In this method, gel samples experienced various degrees of microstructural rearrangements at small amplitude oscillatory shear (SAOS) region (γ = 0.64%) and large amplitude oscillatory shear (LAOS) region (γ = 100%).
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•Formation of stronger SPI gels through incorporation of ChNs.•ChNs increased the gel strength, WHC and viscoelasticity of SPI gels.•ChNs provided a denser and more uniform microstructure for SPI gels.•All gels showed high frequency dependence and type I behavior.•The gel microstructure showed stepwise changes during large deformation.
The present study aims to investigate the impact of ultrasonic treatment on the emulsifying property and emulsion stability of an emulsion system stabilized with soybean protein isolate (SPI) and ...lecithin. Ultrasonic parameters used were ultrasonic powers of 150, 300, and 450 W and ultrasonic durations of 12 and 24 min. Emulsifying properties of emulsions were all improved with different extents after ultrasonic treatments. The emulsion treated at 150 W & 24 min showing the best emulsifying property and emulsion stability than the rest. However, the higher ultrasonic power of 450 W gave negative effects on emulsion stability, with increased particle size and decreased absolute ζ-potential values due to protein aggregation. Prolonged ultrasonic duration from 12 to 24 min resulted in a more stable emulsion under the ultrasonic power of 150 W. However, for ultrasonic powers of 300 and 450 W, the additional ultrasonic energy from prolonging ultrasonic duration from 12 to 24 min generated negative effects to emulsion stability.
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•Emulsion was reconstituted using soybean protein isolate (SPI) and lecithin.•Ultrasonic treatment enhanced the stability of the reconstituted emulsion.•Excess ultrasonic treatment caused the reduction of emulsion stability.•Ultrasonic treatment led to the exposure of hydrophobic regions in soy protein.•Protein aggregation was suspected to cause the reduced emulsion stability.
•Ultrasound treatment increased the solubility of soy protein hydrolysates.•Precipitated peptide aggregates were degraded by ultrasound irradiation.•Ultrasound induced the changes in the ...conformational structure of peptides.•The antioxidant capacity of hydrolysates was increased after sonication.•The morphology of peptide microstructures was changed due to sonication.
The effect of ultrasound on the conformational and physicochemical properties of soy protein isolate hydrolysates (SPHs) was investigated. SPHs were prepared at hydrolysis times of 20 min, 60 min, and 180 min, then treated with ultrasound for 10 min, 20 min, and 30 min at a frequency of 20 kHz and output powers of 150 W and 450 W. The structural properties and antioxidant capacities of the aqueous layer of SPHs (ASPHs) after sonication were evaluated by Fourier-transform infrared spectroscopy (FTIR), intrinsic fluorescence, DPPH radical scavenging activity assays, and microscopy observations. Results obtained showed that ultrasound treatment significantly disrupted the peptide aggregates formed during protein hydrolysis. The protein solubility was significantly increased after sonication (by up to 18.33%), as did the percentage of proteins with MW < 1 kDa in ASPHs. The antioxidant capacity of ASPHs also increased, as measured by DPPH assay. FTIR analysis of ASPHs indicated that the protein secondary structures were different, with an increase in β-sheet and a decrease in α-helix and β-turn. Furthermore, the changes in fluorescence spectra of ASPHs showed the transition of protein tertiary structure with a greater exposure of Trp residues in the side chains. Scanning electron microscope (SEM) and atomic force microscope (AFM) observations of the morphological structure of ASPHs further confirmed the significant effect of sonication on disrupting peptide aggregates. In conclusion, ultrasound can be used as an efficient treatment to promote the solubility of protein hydrolysates.
Abstract
Protein‐based Pickering emulsions are gaining popularity due to their biocompatibility and alignment with people's pursuit of health. This review focuses on recent advances in the ...preparation of Pickering emulsions using various plant and animal proteins from different sources. For sustainability and cost reasons, plant proteins are preferred, while animal proteins provide better nutritional quality. According to the type of plant or animal protein, the suitable modification and preparation methods of stable Pickering emulsion are summarized, including heating, enzyme induction, anti‐solvent precipitation, pH‐cycling, glycosylation, microwave heating, spray drying, and high hydrostatic pressure. Different methods were employed to modify the properties of Pickering emulsion particles at the oil–water interface. To overcome the amphiphilicity limitations of some proteins, substances such as polysaccharides or polyphenols were combined to improve the physical and chemical properties of the particles. Additionally, this review analyzes the effect of different protein particle sources on the properties of Pickering emulsions.
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