Synergistic gellan gum/flaxseed gum composite enhances freeze-thaw stability of soy isolate protein emulsion gels

Emulsion gels are promising fat substitutes for frozen foods but often exhibit poor freeze-thaw stability. This study investigates the synergistic effect of gellan gum (GG) and flaxseed gum (FG) on enhancing the freeze-thaw stability of soy protein isolate (SPI) emulsion gels. Emulsion gels with varying GG/FG ratios (from 5/0 to 0/5) were prepared and characterized. Notably, the composite gel with a GG/FG ratio of 2/3 demonstrated superior freeze-thaw stability, evidenced by 45.21% lower synaeresis rate compared to the only SPI gel after two freeze-thaw cycles. Low-field nuclear magnetic resonance (LF-NMR) analysis revealed a lower T₂ relaxation time in FG-containing gels, indicating enhanced water-binding capacity. Rheological and confocal laser scanning microscopy (CLSM) data further confirmed that this optimal formulation yielded a more compact and ordered network, which effectively inhibited ice crystal growth and droplet coalescence. Spectroscopic (FT-IR) and molecular force analyses suggested that this enhanced stability is underpinned by disulfide bonds reinforced and hydrophobic interactions by the network integrity. In conclusion, this study proposes a synergistic model where GG forms the primary structural backbone, while FG functions as a networking agent, improving water retention and network resilience against ice-induced damage. This work offers an effective strategy for developing robust, polysaccharide-stabilized protein gels for frozen food applications.