Structural modification of Gum Arabic by β-galactosidase hydrolysis: Mechanism of saltiness enhancement and potential application in sodium reduction

Maintaining saltiness perception while reducing sodium content remains a major challenge in low-sodium food design. In this study, Gum Arabic (GA) was modified by β-galactosidase hydrolysis to obtain enzymatically modified GA (β-GA), and its saltiness-enhancing mechanism was investigated from the perspective of polysaccharide structure, mucin (Mu) interaction, and Na⁺ transport. GPC-RI-MALS showed a decrease in apparent weight-average molecular weight from 407 to 367 kDa and a change in the conformation slope from 0.73 to 0.81, consistent with a less compact average conformation. β-GA also showed a smaller hydrodynamic size, while Fourier transform infrared and fluorescence spectra indicated altered glycosidic and hydroxyl environments. In a purified Mu model, β-GA modified aggregate organization and lowered low-shear viscosity; spectroscopy supported non-covalent mucin-polysaccharide association. Dynamic dialysis showed an 8.63% increase in Na⁺ diffusion relative to GA, while ex vivo oral retention imaging suggested greater tracer retention. Time-intensity analysis and electronic-tongue measurements showed increased saltiness intensity and longer overall perception duration. These findings suggest that β-galactosidase-induced remodeling of the GA polysaccharide structure can regulate Mu network organization and Na⁺ transport behavior, providing a physicochemical basis for polysaccharide-assisted saltiness enhancement. Further validation in complex food matrices is still required.