Design and characterization of soy protein isolate-chitosan-dietary fiber ternary composite gels: effects on water holding capacity, texture and structure.

Enhancing the gel properties of soy protein isolate (SPI) is crucial for forming stable gel systems through interactions with other plant proteins and polysaccharides. This study investigated the contribution of different ratios of glutenin (Glu)/gliadin (Gli) and maltodextrin (MD) to SPI–wheat gluten protein (WGP) composite gels. SPI-WGP composite gels were prepared by varying the Glu/Gli ratio (0:10, 3:7, 4:6, 5:5, 6:4, 7:3, and 10:0) and adjusting the MD addition level (0, 2, 4, and 6%). Subsequently, the textural properties, water-holding capacity (WHC), rheological behavior, secondary structure, intermolecular forces, and microstructure of the composite gels were characterized. Results indicated that adding 4% MD with a Glu/Gli ratio of 4:6, compared with the SPI control group gel, the WHC, gel strength, and β-sheet content of the composite gel increased by 37.9%, 164.5%, and 30.6%, respectively. Hydrophobic interactions and hydrogen bonds became dominant after MD incorporation. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) and scanning electron microscopy (SEM) confirmed that the two proteins interact with MD to form a supported, dense, and homogeneous gel system. Excess MD caused phase separation in the composite gel system, disrupting the gel structure. This study provides important references for the development and potential applications of SPI-WGP composite gels.

Effects of Na+ on the cold gelation between a low-methoxyl pectin extracted from Premna microphylla turcz and soy protein isolate

Problems with silver carp protein (SCP) include a strong fishy odor, low gel strength of SCP surimi, and susceptibility to gel degradation. The objective of this study was to improve the gel quality of SCP. The effects of the addition of native soy protein isolate (SPI) and SPI subjected to papain-restricted hydrolysis on the gel characteristics and structural features of SCP were studied. The β-sheet structures in SPI increased after papain treatment. SPI treated with papain was crosslinked with SCP using glutamine transaminase (TG) to form a composite gel. Compared with the control, the addition of modified SPI increased the hardness, springiness, chewiness, cohesiveness, and water-holding capacity (WHC) of the protein gel (p < 0.05). In particular, the effects were most significant when the degree of SPI hydrolysis (DH) was 0.5% (i.e., gel sample M-2). The molecular force results demonstrated that hydrogen bonding, disulfide bonding, and hydrophobic association are important molecular forces in gel formation. The addition of the modified SPI increases the number of hydrogen bonds and the disulfide bonds. Scanning electron microscopy (SEM) analysis showed that the papain modifications allowed the formation of a composite gel with a complex, continuous, and uniform gel structure. However, the control of the DH is important as additional enzymatic hydrolysis of SPI decreased TG crosslinking. Overall, modified SPI has the potential to improve SCP gel texture and WHC.

The effects of cellulose nanocrystals (CNC) and microcrystalline cellulose (MCC) on the gel properties and microstructure of glucono-δ-lactone-induced soy protein isolate (SPI) gels were investigated. The water-holding capacity, gel strength, and viscoelastic modulus of CNC–SPI gels were positively associated with CNC concentration from 0 to 0.75% (w/v). In contrast, MCC–SPI gels exhibited decreased water-holding capacity, gel strength, and viscoelastic modulus. All composite gels displayed high frequency dependence and the typical type I (strain thinning) network behavior. Changes in viscoelasticity under large strain were correlated with differences in the microstructure of SPI composite gels. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) showed that CNC were more evenly and steadily distributed in the protein matrix and formed a compact network structure. In contrast, MCC–SPI gels exhibited a discontinued and rough gel network with some large aggregates and pores, in which MCC was randomly entrapped. Fourier transform infrared spectroscopy (FTIR) and molecular forces results revealed that no new chemical bonds were formed in the gelation process and that the disulfide bond was of crucial importance in the gel system. With the addition of CNC, electrostatic interactions, hydrophobic interactions, and hydrogen bonds in the SPI gel network were significantly strengthened. However, the incorporation of MCC might obstruct the connection of the protein network. It is concluded that both cellulose type and concentration affect gelling properties.

Almond (Prunus dulcis) seeds are good sources of protein that contain healthy fatty acids and dietary fiber. Protein gelation has been traditionally achieved by heating, but other factors can be affected in different gel structures in protein gelation. However, most studies were focused on the heat-induced gel formation of soymilk proteins, there was limited research on the gelling property of almond milk proteins. Therefore, this study aimed to investigate the effects of protein, and calcium chloride concentration, pH, and temperature on almond protein gel-forming and to analyze the physicochemical properties of the almond protein gel. Heat-induced gel formation of almond milk was studied using different ratios of almond seeds to distilled water (1:2, 1:3, 1:4, and 1:5 (w/v)), calcium chloride concentration (0.3, 0.5, and 1%), pH (3, 4, 5, 6, and 7) and temperature (90, 95, and 100º C). Textural profile analysis (TPA), water-holding capacity (WHC), and gel strength of full-fat almond milk (FFAM) gels were evaluated. In addition, the combined factors of FFAM gels were analyzed for the TPA, WHC, gel strength, and rheological measurement. The results showed that the FFAM gel ratio of 1:2 showed the highest hardness (43.03 g), gel strength (0.18 N), and WHC (95.44 %) than other ratios of FFAM gels due to the higher protein, fat, and total solid contents. FFAM (1:2) gel had a significantly different (p˂0.05) with FFAM (1:4) gel on texture properties, gel strength, and WHC. The addition of 0.3% calcium chloride in 1:2 FFAM gels yields the highest gel hardness (44.76 g), strength (0.22 N), and WHC (99.2 %). The 0.3% calcium chloride was significantly different (p˂0.05) between 0.5% and 1% calcium chloride in each FFAM gels on gel strength. The maximum hardness, gel strength, and WHC values obtained the pH 6 in each FFAM gels. However, only a high protein concentration (5.37%) of FFAM (1:2) could be obtained at any pH value when heating. The FFAM gels induced with a temperature of 90º C results in the maximum hardness, gel strength, and WHC in each ratio of FFAM. FFAM gels decreased in gel hardness, strength, and WHC when higher temperatures (95 and 100º C) were applied. High-temperature heating of FFAM leads to higher denaturation of protein which does not set into gels upon cooling. In addition, when the factors were combined to form FFAM gel (1:3+0.3% CaCl2+pH 6+90ºC), the gel strength was significantly different (P˂0.05) from that of FFAM gels for each factor. Moreover, storage modulus (G’- 4359.4 Pa) was higher than loss modulus (G”- 751 Pa) indicating that the gel had formed a continuous network structure. The data obtained from this study provide basic information on the factors and properties of almond milk gel and useful for the application of almond milk gel in vegetarian products.

Elucidating the gelation mechanism of soy-potato protein composite gels: Proteomic, molecular, and structural insights.

The effect and mechanism of soybean insoluble dietary fiber (SIDF) (0~4%) and CaCl2 (0~0.005 M) on the properties of soybean protein isolate (SPI)–wheat gluten (WG) composite gel were studied. It was revealed that the addition of insoluble dietary fiber (1~2%) increased the strength and water-holding capacity (WHC) of the composite gel (p < 0.05) and enhanced the gel network structure compared with the control. WHC and LF-NMR showed that the water-binding ability of the gel system with only 2% SIDF was the strongest. The addition of excessive SIDF increased the distance between protein molecules, impeded the cross-linking of protein, and formed a three-dimensional network with low gel strength. The infrared spectrum and intermolecular force indicated that the interaction between SIDF and SPI were mainly physical, and the hydrophobic interaction and disulfide bond were the main forces in the gel system. The addition of CaCl2 can increase the critical content of gel texture destruction caused by SIDF, and the gel strength attained its peak at 3% SIDF, indicating that appropriate CaCl2 improved gel structure weakening caused by excessive SIDF. This study provides insights in enhancing the production of multi-component composite gel systems.

Incorporating chitin nanocrystal yields stronger soy protein gel: Insights into linear and nonlinear rheological behaviors by oscillatory shear tests

The emulsions prepared by three non-meat proteins, sodium caseinate (SC), soy protein isolate (SPI) and egg white protein (EPI), were individually added to the continuous phase of myofibrillar protein (MP) sol to form MP composite gels to simulate meat products. The research aimed to investigate the effects of Transglutaminase (TGase) on the physicochemical properties, microstructure and water phase distribution of non-meat protein emulsion MP composite gels. The results of this study revealed that TGase played a crucial role in forming a tight gel network structure in the composite gels. This enhanced their ability to retain water and improved their overall gel strength. Additionally, TGase increased the gel formation temperature of myofibrillar proteins. Electrophoresis analysis showed that when catalyzed by TGase, there was a lighter band compared to those not catalyzed by TGase. This indicated that the addition of TGase facilitated cross-linking interactions between meat proteins and non-meat proteins in the composite gels. Furthermore, microscopy observations demonstrated that composite gels treated with TGase exhibited a more uniform microstructure. This could be attributed to an acceleration in relaxation time T2. The uniform network structure restricted the movement of water molecules in the gel matrix, thereby improving its water-holding capacity. Overall, these findings highlight how incorporating non-meat proteins into myofibrillar systems can be effectively achieved through enzymatic treatment with TGase. Such modifications not only enhanced important functional properties but also contributed towards developing alternative meat products with improved texture and moisture retention abilities.

SummaryThe aim of this study was to investigate the effect of the combination of citrus fibre (CF) and soy protein isolate (SPI) on pork myofibrillar protein (MP) gel properties under low‐sodium salt conditions during the heating process. The composite (with CF and SPI) and single (with 1% and 2% NaCl) MP gels properties were evaluated by colour, water holding capacity (WHC), gel strength, rheological properties, microstructure, secondary structure, and water state. The addition of 0.45% CF and 1.5% SPI significantly improved WHC and gel strength, as well as increased the values of G′ and G′′ (P &lt; 0.05). The microstructure indicated that the CF/SPI could decrease the water channels and form a denser structure through filling effects, which was also proved by the fastT21relaxation time. However, the addition of 0.9% CF and 3.0% SPI could inhibit the protein aggregation and disrupt the stable and homogeneous structure. The analysis of the secondary structure showed that the CF/SPI resulted in a lower α‐helix content and a higher β‐sheet content compared with MP gels. This study may provide some guidance for the use of CF/SPI to improve MP gel properties in low‐salt meat products.

Riboflavin, a water-soluble vitamin, is not synthesized in the human body. Hence, developing riboflavin carriers that can be retained in the gastrointestinal system for longer periods can facilitate riboflavin supplementation. The present study aimed to prepare a soy protein isolate (SPI)-κ-carrageenan composite gel-mediated riboflavin delivery model. Additionally, the effects of different concentrations of κ-carrageenan on the micromorphology, gel strength and rheological properties of SPI gels were investigated. The results showed that incorporating high- concentration of κ-carrageenan (0.4 g kg-1) effectively enhanced the interactions among SPI aggregates, increasing the gel frontal strength to 128.65 g and water-holding capacity up to 81.67%. Additionally, κ-carrageenan incorporation enhanced the gel network structure, reduced gel porosity and increased the density of the gel network structure. Compared with SPI gels, SPI-κ-carrageenan composite gel facilitated the targeted release and in vivo degradation of riboflavin, at the same time as delaying the biodegradation of riboflavin in stored gels. Altogether, the findings of the present study provide insights into SPI-κ-carrageenan composite gels regarding gel properties and interaction mechanisms, as well as a strategy for the slow release of riboflavin in the gastrointestinal tract. © 2025 Society of Chemical Industry.

Unveiling structural evolution during high-moisture extrusion of soy protein isolate-wheat gluten systems with soy dietary fiber: A sudden shutdown-based study.

The heated-induced gelation of soy protein isolate at subunit level: Exploring the impacts of α and α′ subunits on SPI gelation based on natural hybrid breeding varieties

Understanding the interactions between polysaccharides and plant proteins is essential for controlling texture in the formulation of alternative food products. This study investigates the influence of pH on rheology and microstructure of composite gels formed from curdlan and soy protein isolate (SPI). Composite gels, prepared at a 1:1 weight ratio of curdlan to SPI to eliminate the influence of mixing ratio, were compared with their respective pure components across pH 5, 7, and 9. In pure curdlan gel, a higher pH (pH 9) resulted in increased linear viscoelasticity, which can be linked to enhanced curdlan solubility, as revealed by scanning electron microscopy. In contrast, the curdlan-SPI composite gels exhibited the strongest gelation at pH 5 (G'~7535 Pa). Microstructural analysis showed that aggregated SPI particles were embedded within the curdlan network at this pH, thus reinforcing its gel strength. At pH 9, the increased solubility of SPI hindered associations of curdlan molecules, leading to weakened gel structure. Under large amplitude oscillatory shear, the composite gel at pH 9 exhibited an earlier onset of nonlinear response compared to the other pH conditions, consistent with diminished structural integrity. X-ray diffraction analysis confirmed the presence of both single- and triple-helix conformations of curdlan, which contribute to gel network formation. However, incorporation of SPI reduced the degree of triple-helix ordering, indicating disruption of curdlan's structural organization. These findings underscore the critical role of pH in modulating the phase behavior and rheological properties of nonionic polysaccharide-protein gels. Such insights are valuable for optimizing the formulation of plant-based gel systems with tailored textural properties for the development of alternative food products.

The effect of high intensity ultrasonic pre-treatment on the properties of soybean protein isolate gel induced by calcium sulfate