Improvement mechanism of network structure and gel strength of konjac glucomannan/xanthan synergistic interaction gel induced by directional freeze-thaw treatment

In the food industry, synergistic interaction gels (SIGs) offer significant potential, due to their easy gelation, enhanced texture tailoring capabilities, and excellent processability. Konjac glucomannan (KGM) and xanthan gum constitute a common pairing of polysaccharides that form SIGs; however, their gel strength remains insufficient for practical applications. This study demonstrates that directional freeze-thaw (DFT) treatment reinforced KGM/xanthan SIGs by orienting molecular chains and promoting reassembly during the successive freeze-thaw cycles. In the cyclic DFT treatment, the type-A aggregates contents gradually increased revealed by the increased enthalpy change values (ΔH₁) and area of the peak-1 centered at q = 0.02 Å⁻¹ (A_peak-1), along with reducing the average size of high-density domains (scatters) and compacting the arrangement of these scatters (signified by the decreased average size of scatterers (d₁) and increased the fractal dimension (n)). These thereby enhanced the gel integrity and almost double the strength across various deformations after three cycles of DFT. For sample with a component ratio 4:6 for KGM: xanthan, its average storage modulus at 25–30 °C (G_A^′) increased from about 100 Pa to 200 Pa, and the hardness increased from 0.19 N to 0.34 N. These insights will facilitate the design of structured gel foods and broaden their applications in anisotropic-textured application.