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To investigate the impact of different polyphenols on the gel properties of gellan gum (GG) and the interaction mechanism, experiments and virtual molecular simulations were conducted based on nine representative polyphenols. Rheological analysis revealed that all the GG/polyphenol composite hydrogels were pseudoplastic fluids with a low viscosity. The storage modulus (G′) of hydrogel containing only GG was 28.3 Pa at 0.1 Hz. The addition of gallic acid (GA), puerarin (PUE) or cyanidin cation (CC) significantly increased the G′ of the hydrogel by 4.9-fold, 3.3-fold, and 2.6-fold, respectively. The introduction of GA reduced the water holding capacity (WHC) of the hydrogel to 62.0 %, while the other eight polyphenols increased the WHC to nearly 100 %. Regular, intact and dense honeycomb mesh structures were observed in the GG/GA, GG/PUE, GG/CC and GG/catechin microstructures. The molecular docking results indicated that, among the nine polyphenols, PUE had the strongest affinity for GG with an interaction energy of −18.64 kcal/mol. According to the results of molecular dynamics simulation, the total energy of the composite system interacting with water corresponded well with the G′ of the composite hydrogels. The GG/GA system with the highest G′ had the lowest total energy of −15655.82 kJ/mol. Hydrogen bonds were the main driving force for improving the strength and maintaining the structural stability of the composite hydrogels. Therefore, this study confirmed the various effects of nine polyphenols on GG hydrogels and provided a novel basis for investigating the synthesis and gelation mechanism of polysaccharide-polyphenol composite hydrogels. [Display omitted] • The properties of GG hydrogel varied after mixed with different polyphenols. • Molecular docking elucidated affinity and binding modes between GG and polyphenols. • Relationship between gel strength and binding energy provided by MD simulations. • Hydrogen bonding played major roles in gel formation and binding process. [ABSTRACT FROM AUTHOR]

To develop composite hydrogels based on low acyl gellan gum (GG), the effect of puerarin (PUE) on the gel properties of GG was investigated. The results showed that the maximum storage modulus (G ′) of the 1.2 % GG/0.8 % PUE composite hydrogel was 377.4 Pa at 0.1 Hz, which was enhanced by 4.7-fold compared with that of 1.2 % GG. The melting temperature of this composite hydrogel increased from 74.1 °C to >80.0 °C. LF-NMR results showed that a significant amount of free water was present in the hydrogel matrix. The surface structure aggregation and the shrinkage of the honeycomb meshes in the composite hydrogel proved the cross-linking of PUE and GG. XRD, FTIR and molecular simulation results illustrated that hydrogen bonds were the most important factor controlling the interaction between GG and PUE. Thus, the GG/PUE composite hydrogel has good elasticity, thermal stability and water retention, which lays a good foundation for further application in the food industry. [ABSTRACT FROM AUTHOR]

• Gellan gum (GG) improved gel formation of protein isolate from P. crocea roe (pcRPI). • GG improved the rheological properties and water holding ability of pcRPI gels. • The pcRPI-GG binary gels showed denser, more aggregated network structure. • GG improved the protective effects of curcumin by pcRPI gels with control release. The aim of this study was to investigate the effect of gellan gum (GG) on the cold gelation of large yellow croaker roe protein isolate (pcRPI). The water-holding ability and storage modulus of the pcRPI-GG binary gels increased with the GG concentration, where the storage modulus of the pcRPI-0.2% GG gel was approximately 30.7 times that of the pure pcRPI gel. Compare to the other binary gels, pcRPI-0.2% GG gels exhibited a lower lacunarity and higher junction density, with a denser, more aggregated microstructure. Consequently, curcumin was embedded in pcRPI-0.2% GG gels, and simulated gastrointestinal digestion test results showed that GG addition effectively protected and slowed curcumin release in the gastrointestinal environment. These findings may contribute to elucidating the interaction of pcRPI with GG and demonstrate the potential of binary gels for the embedding and delivery of active substances. [ABSTRACT FROM AUTHOR]

• Low-acyl gellan gum had effect on gelation of scallop male gonad hydrolysates (SMGHs). • Gel strength of SMGHs was increased with increasing of low-acyl gellan gum (GG) dose. • The thermal stability of SMGHs gel was improved by the addition of GG. • The promoting effect of GG on SMGHs gel was related to the water migration. • The SMGHs/GG composite gels showed a regular and homogenous network. This study aimed to examine the gelation and microstructural properties of scallop male gonad hydrolysates (SMGHs) in the presence of low-acyl gellan gum (GG) at different mass ratios. The rheological results showed that both elastic modulus and thermal stability of SMGHs were significantly improved by the addition of GG. Meanwhile, the relaxation time T 23 was significantly reduced in SMGHs/GG by low-field nuclear magnetic resonance, indicating a strong interaction between SMGHs and GG. Fourier transform infrared spectroscopy indicated the blueshift of amide I and II peaks in SMGHs/GG further demonstrated the electrostatic interaction between SMGHs and GG. The network structure of SMGHs/GG binary complexes was more compact and the surface was smoother than that of SMGHs by cryo-scanning electron microscopy. Furthermore, increasing the content of GG in the SMGHs/GG binary complex significantly reinforced the gel strength and promoted the gelation process. [ABSTRACT FROM AUTHOR]