Fabrication and Characterization of Sonicated Peach Gum-Sodium Caseinate Nanocomplexes: Physicochemical, Spectroscopic, Morphological, and Correlation Analyses

Abstract

The aim of this study was to develop stabilized nanocomplexes of peach gum polysaccharide (PG) and sodium caseinate (SC) and evaluate the influence of high-intensity ultrasonication (ULS) on their structural and emulsification characteristics. The structural arrangement of sonicated PG-SC nanocomplexes ((PG-SC)_U) was ascertained through Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and intrinsic fluorescence spectroscopy. The FTIR analysis revealed a reduction in α-helix conformation and a higher random coil conformation in (PG-SC)_U. Additionally, the utilization of ULS resulted in an enhancement of the fluorescence intensity and the surface hydrophobicity of (PG-SC)_U. The mean droplet size and zeta potential of (PG-SC)_U treated at 450 W power for 13 min were measured to be 166.85 ± 2.17 nm and − 17.84 ± 1.49 mV, respectively. Additionally, the emulsifying stability index of (PG-SC)_U at 450-W power was found to be higher (92.04 ± 0.1%) as compared to other ULS power treatments. The current study’s findings suggest that ULS treatment at 450-W power significantly altered protein complex spatial conformations, ultimately improving their functional characteristics. The (PG-SC)_U exhibited a compact and uniform spherical structure when examined using confocal laser scanning and scanning electron microscopy techniques. The Pearson correlation coefficient showed an inverse relationship between particle size, polydispersity index (PDI), emulsion stability index (ESI), emulsifying activity index (EAI), α-helix, and surface roughness (Ra and Rq). However, the EAI/ESI had a relatively weak correlation with β-sheet and β-turn conformations. The stability of the interaction between PG and SC (casein protein) was verified using molecular docking, which demonstrated the presence of traditional hydrogen bond and van der Waals force interactions. The selection of ULS power can improve the structural and emulsifying properties of (PG-SC)_U, indicating its potential use in various food processing applications, particularly in the development of dietary supplements and functional foods.