Regulation of composite particle structure by soy isolate protein-citrus pectin mass ratio and its mechanism of influence on interfacial activity and stabilizing properties.
Despite the advantageous functional properties of soybean protein isolate (SPI), its inherent conformation is susceptible to environmental influences, thereby limiting its utility in food systems. This work investigated the effect of mass ratio between soybean protein isolate (SPI) and citrus pectin (CP) on the structure and functionality of composite particles. Results showed that a 1:1 SPI-to-CP ratio produced the smallest particle size (280.13 nm) and the best dispersion stability. This ratio also significantly improved emulsifying activity (EAI: 54.80 m2/g) and emulsion stability (ESI: 105.91%), while enhancing the adsorption capacity of interfacial proteins. The composite particles were driven by hydrogen bonding, hydrophobic interactions, and electrostatic forces. These interactions promoted the conformational unfolding of SPI, increasing surface hydrophobicity and facilitating a structural transition from α-helix to β-sheet. This work provides fundamental insights for designing food-grade particles with enhanced interfacial activity and stability.
Soy protein isolate (SPI)–polysaccharide-stabilized high internal phase emulsions (HIPEs) are promising fat alternatives for meat analogs. However, the distinct contributions of polysaccharide charge and viscosity to emulsion formation, stabilization and meat analog quality remain unclear. This study systematically investigated five polysaccharides with different charges and viscosities, namely cationic chitosan (CS), neutral locust bean gum (LBG) and guar gum (GG), and anionic xanthan gum (XG) and high methoxyl pectin (HP), in modulating SPI structure, HIPE performance, and plant-based patty quality. Results showed that polysaccharide charge dominated SPI-polysaccharide interactions and dictated SPI conformational remodeling. Neutral polysaccharides interacted with SPI through hydrogen bonding/hydrophobic interactions, significantly increasing the β-sheet content (GG: from 35.91% to 43.23%), and achieving the smallest initial droplet size through a high interfacial adsorption rate (GG: 6.81 μm). During emulsion stabilization and flavor retention, viscosity was the predominant factor. High-viscosity XG and GG excelled in inhibiting droplet aggregation, reducing gravitational separation, and maximizing volatile flavor retention under both heating and storage. At the application stage, viscosity predominantly influenced the hardness of patties. This study reveals the division of labor between polysaccharide charge and viscosity across different performance dimensions of HIPEs, guiding polysaccharide selection for tailoring HIPEs in meat analogs.
Ying Chen, Jiamei Yu, Lin Zhang et al.· Current Research in Food Sci...· 0 citations
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.
Yuexin An, Ruqi Guo, Hongli Yin et al.· International Journal of Bio...· 0 citations
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
This study investigates how electrostatic interactions between whey protein isolate (WPI) and polysaccharides (konjac glucomannan, guar gum, pectin, sodium alginate, chitosan) affect the stability and encapsulation of high-internal-phase emulsions (HIPEs, oil fraction >74%), revealing charge-driven structural and network stabilization mechanisms. The findings demonstrate that anionic WPI (pH 7.0) alone was more effective than cationic WPI (pH 4.0) in stabilizing oil-in-water HIPEs. Neutral polysaccharides enhanced emulsifying performance through viscosity-induced stabilization. While electrostatic repulsion increased ζ-potential of the complexes, thereby synergistically strengthening hydrophobic interaction-driven emulsifying activity. In contrast, excessive attraction (pectin, ζ-potential -17.0 mV) destabilized structural network through bridging or depletion flocculation, whereas moderate attraction (sodium alginate, ζ-potential -11.5 mV), facilitated the formation of stable emulsion systems. Notably, sodium alginate-WPI systems demonstrated robust stability (for 4 months) across all electrostatic conditions and offered excellent biocompatibility (<5%) and probiotic protection (>9.05 log CFU/mL). Collectively, these findings elucidate the mechanism of electrostatic tuning in stabilization of HIPEs, providing a promising approach for probiotics delivery.
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
Proteins are effective carriers for polyphenols, yet whether structural differences between plant- and animal-derived proteins influence the delivery and functionality of polyphenols in their nanocomplexes remains unclear. In this study, soy protein isolate-curcumin (SPI-CUR) and myofibrillar protein-curcumin (MP-CUR) nanocomplexes were fabricated via a pH-driven method, and their physicochemical properties, interaction mechanisms, and cryoprotective effects on surimi were investigated. Both nanocomplexes achieved high encapsulation efficiencies (90.63% for SPI-CUR and 83.29% for MP-CUR) and thus exhibited enhanced antioxidant activity. CUR loading induced conformational changes in the protein carriers, as evidenced by increased α-helix content and decreased β-sheet content, suggesting the formation of a more compact structure. Meanwhile, this conformational change was accompanied by a marked reduction in particle size, with SPI-CUR reaching 66.13 nm. Molecular docking further revealed that hydrophobic interactions and hydrogen bonding were the primary forces stabilizing both nanocomplexes. During freeze-thaw cycles of surimi, both SC and MC nanocomplexes were superior to commercial cryoprotectants in preserving product quality, evidenced by improved water-holding capacity, enhanced gel properties, and inhibited protein oxidation. Notably, the two nanocomplexes exhibited distinct protective profiles depending on the protein source. MP-CUR demonstrated superior preservation of gel texture by minimizing thawing loss to 0.53% and maintaining high hardness (425.50 ± 34.85 g) and springiness (0.81 ± 0.03), which facilitated the formation of a denser gel network. In contrast, SPI-CUR demonstrated superior viscoelasticity and yielded the highest storage modulus (G'). This study establishes a foundation for the rational design of natural and efficient surimi cryoprotectants derived from protein-polyphenol complexes.
Xiaoyun Liu, Yang Meng, Zhikun Yang et al.· Journal of Food Science· 0 citations