Fabrication and characterization of novel bigel systems based on natural gums: rheological, textural, and thermal...

The fabrication of novel bigel formulations utilizing natural gums presents an attractive and valuable approach for the development of healthy and functional food products. The goal of the current investigation was to establish new bigel systems incorporating various hydrogels matrices, specifically alginate (ALG), basil seed gum (BSG), and Alyssum homolocarpum seed gum (AHSG) at different mixing oleogel/hydrogel ratios (100:0, 99:1, 95:5, and 90:10). Initially, the flow behavior characteristics of different concentrations of ALG (2% w/w), AHSG (0.25, 0.50, 0.75, and 1.0% w/w), and BSG (1.0, 1.5, and 2.0% w/w) were determined to identify the optimal hydrogel concentration for bigel fabrication. The rheological analysis confirmed that all tested hydrogel concentrations exhibited shear-thinning non-Newtonian behavior (power law index, n < 1). Subsequently, the viscoelastic properties of the oleogel and ALG-bigel samples were characterized. The results indicated that the bigel systems displayed a dominant solid-like network structure over a liquid-like behavior, evidenced by the storage modulus (G') consistently exceeding the loss modulus (G"). No significant alterations were observed in the mean particle size or morphological characteristics of the bigels (p > 0.05). Furthermore, the thermal stability of the bigels' network matrix demonstrated an increase proportional to the increase in the hydrogel fraction incorporated into the system. Textural profile analysis revealed that the hardness and adhesiveness of the fabricated bigels ranged from 319.87 to 472.27 gf and 143.07 to 242.23 gf.s, respectively. In conclusion, these findings confirm that the natural hydrocolloids AHSG and BSG can effectively mimic the structural and functional role of alginate hydrogel in the bigel systems.