Synergistic effects of ultrasound and Na+ on soy protein isolate-hemp protein isolate-carboxymethyl cellulose composite emulsion gels: Evaluating the potential for low-salt gel foods.
Jul 2026· International Journal of Biological Macromolecules· Vol 376, pp.
153335
· 0 citations· 76 references
Medicine
Abstract
This study aimed to address the structural deficiency of plant protein gels by investigating the impact of ultrasound power levels and Na+ concentrations on the characteristics of soy protein isolate (SPI)-hemp protein isolate (HPI)-carboxymethyl cellulose (CMC) composite emulsion gels (S/H/C gels). The results revealed that low-concentration Na+ (100-300 mM) can effectively shield the charges on protein surfaces, facilitate efficient aggregation of protein molecules, and encourage the conversion of some α-helix into β-sheet, thereby promoting the creation of a gel network structure. Ultrasonic treatment (400 W) further induced protein denaturation, promoting the exposure of hydrophobic groups and the creation of disulfide bonds, resulting in a well-developed three-dimensional network structure. At an appropriate Na+ concentration (300 mM), gel hardness increased from 97.16 N to 104.64 N, the storage modulus G' reached its maximum value, and the proportion of β-sheet structure increased significantly. This demonstrated excellent water-holding capacity (increased by 15.56%) and digestive characteristics. Nevertheless, excessive ultrasonic power (600 W) or high Na+ concentration (600 mM) led to excessive protein aggregation and loosening of the network structure, disrupting the continuity of the oil droplet-protein interface and thereby degrading the performance of the emulsion gel. This study elucidates the synergistic mechanism between ultrasound and Na+ in controlling the multidimensional qualities of plant protein emulsion gels, providing a theoretical basis for developing low-salt gel foods.
The textural properties of food colloidal systems are highly dependent on the gelling characteristics of animal-derived proteins (such as egg protein, EP) and polysaccharides (such as starch, pectin, and gums). The development of plant-based protein alternatives faces challenges such as insufficient gel strength and poor structural stability. This study focused on purified Chlorella protein extract (PCPE). To address the insufficient gel performance of PCPE, a synergistic optimization strategy of "modification combined with calcium ion regulation" was proposed. Results revealed that alkali treatment strengthened ionic interactions while weakening hydrogen bonds and hydrophobic interactions, promoting protein molecular rearrangement and resulting in a narrower and more concentrated particle-size distribution. This increased the initial storage modulus to 136 Pa, comparable to that of EP. TGase treatment catalyzed protein-protein and protein-polysaccharide covalent cross-linking, forming a dense network structure and significantly increasing gel hardness to approximately 1.5 times that of EP. Furthermore, the addition of calcium ions synergistically enhanced gel strength via salt bridge formation, further elevating the initial storage modulus to 297 Pa. However, a high calcium concentration (25 mM) led to an approximately 20% reduction in water-holding capacity for TGase-treated PCPE gels. This study elucidates the multidimensional regulatory mechanisms underlying enhanced plant-protein gelation and provides a strategy for developing sustainable plant-based gelled foods.
Hao Chen, Qun Gao, Ruoyu Wu et al.· International Journal of Bio...· 0 citations
In this study, phytic acid (PA) was employed as a multifunctional crosslinking agent to fabricate dual-crosslinked composite films based on soy protein isolate (SPI) and carboxymethyl cellulose (CMC), with glycerol as a plasticizer and gelatin as a processing aid to improve film flexibility and processability, thereby overcoming the performance decline of conventional soy protein-based films under high-humidity conditions. The structural, mechanical, hydrophobic, thermal, and barrier properties of the films were systematically characterized. The results demonstrated that PA-mediated dual crosslinking significantly enhanced the overall performance of the composite films. The optimized formulation (SPI-0.5CMC-PA) exhibited a water contact angle of 106.91°, indicating substantially improved surface hydrophobicity. Meanwhile, the dual-crosslinking network simultaneously increased both tensile strength and elongation at break, reaching 13.22 MPa and 39.93%, respectively, accompanied by enhanced thermal stability. XRD and DSC analyses confirmed excellent compatibility components, revealing a more amorphous yet structurally intact network without phase separation. FTIR spectra further verified the formation of electrostatic salt bridges and hydrogen-bonding interactions within the PA-mediated dual-crosslinked network. Overall, this dual-crosslinking strategy yields a green, mechanically robust, and hydrophobic film, demonstrating significant promise for moisture-resistant food packaging while offering a new route to bio-based hydrophobic materials.
X. Ji, J. K. Wang, Z. Chen et al.· International Journal of Bio...· 0 citations
Soy protein isolate (SPI) is widely used as a plant protein ingredient. This study modified SPI by ultrasound-assisted laccase treatment (U + La; 150, 300, 450, and 600 W), evaluated its functional properties, and further analyzed the related physicochemical and structural changes. SPI treated with 300 W ultrasound and laccase (UL3) showed the best overall functionality, with the highest water-holding capacity (93.39%), emulsion stability index (42.60 ± 2.24 min), and foaming capacity (169.29%). UL3 also showed a relatively small particle size (362.80 nm) and the highest absolute zeta potential (27.78 mV). Electrophoretic and chromatographic analyses indicated increased high-molecular-weight aggregates after U + La treatment. Spectroscopic and microstructural results suggested that moderate U + La treatment was associated with SPI conformational changes and a compact gel network. Overall, UL3 improved SPI model functionality and showed application potential as a modified plant protein ingredient.
Jiaxin Guo, Qinggang Xie, Yilin Sun et al.· Food Research International· 1 citation
Mixed-protein gel systems have emerged as an effective strategy for tailoring textural and structural properties in sustainable food systems. In this study, the effects of varying ratios (1:1, 2:1, 4:1) and thermal pretreatment (75, 85, 95 °C) of soy protein isolate (SPI) on the gelation behavior of transglutaminase (TGase)-crosslinked fish gelatin (FG) were systematically investigated. The results showed that TGase-induced FG-SPI complexes exhibited strengthened intermolecular interactions. However, the globular structure of native SPI constrained the formation of a dense and continuous porous microstructure characteristic of TGase-crosslinked FG, thereby reducing the gel strength of the mixed gels. Preheating SPI at 75 °C promoted partial unfolding of the protein, generating additional TGase-accessible reactive sites and intensifying hydrophobic interactions and disulfide bonding, which collectively improved the gel strength and textural properties of the FG-SPI gels. These findings provide a robust framework for designing tunable, sustainable mixed-protein gels for diverse food applications.
The protein-based emulsion-filled gel serves as a delivery carrier for hydrophobic active ingredients, and its performance is significantly influenced by the type of filler. Rice bran oil body (RBOB), as a plant-based natural filler, the regulation of its role in the protein-filled gel system remains unclear. In this study, different concentrations of RBOB were incorporated into the soybean protein isolate (SPI) gel matrix to construct a composite emulsion-filled gel system. The effects of RBOB filling amount on the gel structure characteristics were systematically evaluated. Subsequently, the optimal concentration of RBOB was used to encapsulate lycopene, and its in vitro digestion release behavior and bioaccessibility were assessed. The results showed that RBOB (6.25%) formed an active filler effect through its surface proteins' hydrophobic interaction with the SPI matrix and interface bridging. This enhanced the compactness and continuity of the gel network, improved the structural properties and water holding capacity of the gel, and achieved effective regulation of the gel's microstructure. In terms of delivery performance, RBOB efficiently loaded lycopene in a lipid-soluble core. The physical barrier formed by the interface protein layer of RBOB and the SPI network effectively delayed the chemical degradation of the active components. Meanwhile, the unique structure of RBOB promoted the formation of mixed micelles, significantly enhancing the micelization rate and bioaccessibility of lycopene. In conclusion, RBOB can exert dual regulatory effects at both the structural reinforcement and functional delivery levels, providing theoretical guidance for the efficient utilization of hydrophobic active factors.
Fei Gao, Xiaoyu Han, Xiaofang Wang et al.· International Journal of Bio...· 1 citation
Understanding how ionic valence regulates the hierarchical structure evolution of composite plant protein gels is essential for the rational design of functional food hydrogels. In this study, soy protein isolate (SPI)-potato protein (PP) hydrogels were employed as a model system to investigate the effects of ionic valence on multiscale structural characteristics and functional properties. Na+ at 100 mM formed a homogeneous dense network via electrostatic shielding, achieving peak water-holding capacity (WHC, 99.41%) and hardness among the Na+ series, accompanied by increased β-sheet content and hydrogen bonding. Ca2+ induced strong aggregation via ionic bridging, constructing a reinforced and elastic network at 20 mM, with the highest proportion of strongly bound water (9.20%). Fe3+ induced charge reversal at high concentrations through excessive charge neutralization, triggering rapid heterogeneous aggregation and increasing α-helix content, which ultimately caused deterioration in water retention and mechanical stability. Intermolecular force analysis revealed that ion treatment further strengthened the already dominant hydrophobic interactions while weakening electrostatic interactions.
Wen Qi, Yanlinyuan Zhang, Songlin Li et al.· Food Chemistry· 0 citations
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