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Gelatin-polysaccharide interactions have garnered significant attention in recent years due to their profound effects on the properties (rheology and structure) of various food products. This study investigates the interaction between Lycium barbarum polysaccharide (LBP) and gelatin, focusing on the impact of different concentrations LBP (0–2.0%, w/v) on gelation behavior, water mobility, and gelatin structure. The results show that the addition of LBP initially increases and then decreases the gel strength and hardness of the gelatin. Incorporating LBP into gelatin leads to decreased brightness, gelling temperature (T g), gelation rate (k gel), immobile water content, and residue, while increasing the redness, yellowness, bound and free water content, and thermal stability. Fourier transform infrared spectroscopy (FTIR), x-ray diffractometer (XRD), cryogenic scanning electron microscopy (Cryo-SEM), and atomic force microscopy (AFM) analyses provide evidence for the existence of hydrogen bonds, electrostatic interactions, and ionic bond interactions between LBP and gelatin, in addition to covalent bonds formed through the Maillard reaction. Moreover, LBP induces changes in the structure of gelatin, including alterations in secondary structure, crystalline structure, and microstructure. AFM observations further indicate that LBP promotes the formation of gelatin aggregates. These findings present promising avenues for the application of LBP-gelatin composite gels as novel materials in the food industries. [Display omitted] • Gelation behaviors and structural changes reveal LBP-gelatin interaction. • LBP-induced changes in gelatin's water mobility. • Incorporation of LBP enhances thermal stability of gelatin. • Modification of gelatin structure by LBP confirmed by FTIR, XRD, Cryo-SEM, and AFM. • LBP-gelatin interaction: Hydrogen bonds, electrostatic and ionic interactions. [ABSTRACT FROM AUTHOR]

The objectives of this study were to identify the chemical composition, monosaccharide composition, and molecular weight (Mw) of the polysaccharide (LBP) extract from Lycium barbarum L., and investigate the effects of Ca2+ on the zeta potential, rheological properties, infrared spectra (IR), and structure as well as the gelation mechanism of the LBP. The results showed that the LBP was an acidic glycoprotein mixture with an Mw of 4.05 × 105 Da. The addition of Ca2+ first decreased and then increased the absolute value of zeta potential. The elastic modulus (G'), complex viscosity (η*), and stress relaxation modulus (G(t)) of LBP increased with an increase of Ca2+ concentration, and reached the maximum value at the concentration of 12 mM. IR showed that the typical peak wavenumber of the LBP has changed in the presence of Ca2+. SEM and AFM analysis confirmed that Ca2+ could improve the formation of gel network structure in LBP. In addition, the electrostatic interaction and the calcium bridges produced by the addition of Ca2+ played a key role in the formation of the gel network structure. These findings will benefit the application of LBP in the food and pharmaceutical industries. [Display omitted] • Effect of Ca2+ on the rheological properties and structure of LBP was investigated. • Gelation mechanism of LBP was also elucidated. • Increasing concentration of Ca2+ improved rheological properties of the LBP gels. • Ca2+ increased the stability of LBP gel network structure. • Electrostatic interaction was crucial to LBP gel network structure formation. [ABSTRACT FROM AUTHOR]