Reconstituted soybean protein isolate emulsion gel induced by transglutaminase: structure, stability, and application in quercetin delivery.

Controlled thermal unfolding of soy protein isolate modulates transglutaminase-induced gelation and network structure of fish gelatin.

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.

Enzymatic Construction of Whey Protein-Arabinoxylan Conjugate Particles and Their Regulation on the Stability and Curcumin Delivery Property of High Internal Phase Pickering Emulsions

Comparative Effects of Protein Glutaminase and Transglutaminase on Fermentation-Induced Gelation of Pea, Faba Bean, and Soy Protein Isolates

Pea, faba bean, and soy protein isolates (PPI, FPI, SPI) are increasingly used as primary ingredients for developing plant-based gels for cheese and meat analogues. A major challenge is their limited functionality, including low solubility, poor emulsifying capacity, and restricted molecular flexibility, which together constrain their ability to form strong and cohesive gels. Controlled protein modification and optimized processing conditions are therefore required to tailor their gelation behaviour. This study aimed to modify the gelation properties of PPI, FPI, and SPI using protein glutaminase (PG) and transglutaminase (TG), and to evaluate fermentation-induced gelation in emulsion-based systems relevant for future plant-based food applications. PG treatment resulted in 12–16% deamidation across the three proteins but increased solubility only in SPI, while zeta potential remained unchanged, indicating minimal changes in net surface charge. Lactic-acid bacteria fermentation enhanced gelation for all proteins, yielding gel hardness values of 46–102 g and confirming that acidification is the primary driver of network formation. TG addition during fermentation markedly increased gel hardness in all proteins (128–402 g), with the strongest effect observed in SPI. PG treatment alone did not affect the hardness of fermented gels, but it modulated TG-induced gelation in a protein-specific manner. In SPI, PG reduced TG-induced gel hardness to 303 g, likely due to increased soluble proteins and water retention, whereas FPI showed no change and PPI exhibited a slight increase to 176 g. These findings highlight the interplay between PG-induced deamidation and TG-mediated cross-linking and demonstrate that these interactions are strongly protein dependent.

Comparative Effects of Soybean Protein Isolate- and Myofibrillar Protein-Based Curcumin Nanocomplexes on the Freeze-Thaw Stability of Surimi.

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.

Impact of rutin-protein nanoparticles on extruded recombinant rice: structure, digestibility and in vitro fermentation.

BACKGROUND Rutin, a flavonol polyphenol, inhibits α-glucosidase activity and reduces starch digestibility, yet its application is limited by poor aqueous solubility, poor thermal stability, and low bioaccessibility. Rutin-protein nanoparticles have been shown to improve rutin stability. This study aimed to investigate how rutin-protein nanoparticles modulate the digestibility of extruded recombinant rice through multi-scale structural characterization, in vitro digestibility analysis, and in vitro fermentation evaluation. RESULTS Multi-scale structural analysis revealed that rutin was successfully incorporated into the recombinant rice matrix, interacting with starch chains through hydrogen bonding. This interaction promoted the transformation of starch crystallinity from A-type to A- + V-type. Additionally, the short-range order and the content of single and double helices increased. In vitro digestion experiments demonstrated that the bioaccessibility of rutin in the recombinant rice reached 92.49% after co-extrusion with rutin nanoparticles. The resistant starch content was significantly increased, while C∞ (final digestion extent) and eGI (estimated glycemic index) value were significantly reduced. Moreover, in vitro fermentation results indicated that the recombinant rice with rutin nanoparticles contributed to reducing gas production and increasing the yields of propionate and butyrate. CONCLUSION Rutin nanoparticles modulate starch digestibility through a dual mechanism involving the modification of starch structural domains and rutin bioaccessibility. This study provides a novel strategy and technical support for the development of low-glycemic-index functional staple foods. © 2026 Society of Chemical Industry.

Preparation, characterization, stability, and application in curcumin of the emulsion gels stabilized with coconut cake albumin modified by ultrasonication and carboxymethylation

Curcumin has applications in food and medical industries, but its stability and bioaccessibility are poor. Coconut cake albumin (CCA) has potential as a component of the curcumin-loading system; however, relative data are scare. Herein, emulsion gels were formed using coconut cake albumin modified by ultrasonication and carboxymethylation (CCA-UC) in this study. The results evidenced that ultrasonication and carboxymethylation increased the emulsifying capacity (from 67.51 to 143.65 m 2 /g) and emulsion stability (from 70.37 to 87.18%) of CCA by improving its solubility and interface sorption capacity, enhancing the zeta potential, and reducing droplets’ size ( p  < 0.05). CCA and CCA-UC formed compact emulsion gel when concentration was more than 10 g/100 g. Compared with the CCA-emulsion gel, CCA-UC-emulsion gel had more compact and denser gel structure, higher crystallinity (38.65%), bound water content and viscosity, and lower energy storage ( G’ ), loss modulus ( G” ), and loss factor. Furthermore, CCA-UC-emulsion gel showed superior thermal and oxidative stability, and higher chewiness (35.83 g), springiness (0.90), hardness (67.44 g), and cohesiveness (0.85) than CCA-emulsion gel. Additionally, CCA-UC-emulsion gel exhibited superior intestinal digestion rate, higher curcumin encapsulation (89.64%) and loading efficiency (204.01 μg/g), better photostability, and superior bioaccessibility (49.08%). However, more specific mechanisms should be investigated in the further work. These findings revealed that ultrasonication assisted with carboxymethylation was an effective way to improve the emulsion gel properties of CCA and increase the bioaccessibility of curcumin. However, more specific mechanisms should be investigated in the further work.