Soluble dietary fibers as structuring agents in gelatin gelation: Effects on phase behavior, network formation, water mobility, and colorant stability in low- and high-solid matrices

This study evaluates soluble dietary fibers (SDFs) as structuring agents in gelatin-stabilized confectionery by comparing their effects on gelation in low- and high-solid matrices, with emphasis on phase behavior, network architecture, water states, and functional properties. Five commercial SDFs, with DP 4–18, were examined, including xylooligosaccharides (XOS), fructooligosaccharides (FOS), polydextrose (PD), resistant dextrin (RD), and native inulin (IN). All SDFs elevated T gel and T melt in dose- and DP-dependent fashions. At high levels (>30 %), PD or RD caused viscosity-driven kinetic trapping and protein-in-polysaccharide phase separation, yielding coarse, weakened gels, whereas IN solidified into ultra-rigid composite networks with gelatin. FOS remained fully miscible and optimally enhanced elasticity and thermal stability without severe kinetic trapping on gelation. Low-field NMR showed a progressive shift from high to low water mobility with increasing solids, explaining improved WHC and heat resistance. In high-solid gels with allulose ( A w 0.58–0.65), the absence of free water, together with kinetic trapping and demixing, limited long-range network development and promoted Maillard browning at elevated storage temperatures. Incorporating 0.5 % betanin into these matrices significantly improved its gastrointestinal retention and storage stability, though performance varied with SDF type. Overall, SDF selection governs not only gel mechanics and water mobility but also colorant protection in clean-label gummies.