Influences of cations on the gelation-promoting effect of konjac glucomannan on the phase transition of κ-carrageenan

Synergistic interaction gels can be created by blending konjac glucomannan (KGM) and κ-carrageenan (κ-Car), where the flexible KGM chains suggest an entropy-driven promotion effect on κ-Car phase transition, increasing its setting temperature (ΔTs) and melting temperature (ΔTm). However, the addition of KCl or CaCl₂ gradually weakened this promotion, reducing the ΔTs and ΔTm of the KGM/κ-Car. These salts also caused notable microstructural changes, including thick fibrillar structures and short dense bundles at ≥0.03 mol/L Ca²⁺, revealed by AFM and SEM. SAXS results showed that both domain size and correlation length increased with increasing cation concentration, indicating a more interconnected network and enhanced gel strength. Consequently, gel hardness increased to 729 g (K⁺) and 774 g (Ca²⁺). However, excessive Ca²⁺ led to over-crosslinking and weakened gels. These findings highlight the balance between entropy-driven synergy and ionic crosslinking, providing guidance for designing KGM/κ-Car gels with tailored synergistic properties.