Development and characterization of inulin–lecithin bigels with β-sitosterol and beeswax as structuring agents for spreadable fat applications

This study developed and investigated inulin–lecithin-based bigels (ILBs) incorporating β-sitosterol (SIT) or beeswax (BW) as crystalline structuring agents, aiming to improve the limited plasticity and weak structural properties of conventional ILBs. Both β-sitosterol and beeswax were employed to modulate the physical properties of bigels for their potential use as solid fat replacers. The addition of β-sitosterol or beeswax converted the control formulation from a free-flowing system into a structured bigel, with beeswax forming denser and more homogeneous crystalline networks. Control ILBs exhibited a hardness of 0.040 N, compared to 0.391 N for 4.5 %BW-bigel, confirming the significant structural enhancement. Microscopy, texture profile analysis, and oil/water-binding capacity tests indicated that beeswax more effectively enhanced gel strength, plasticity, and stability, especially at higher concentrations. In the beeswax group, increasing concentration from 1.5 % to 4.5 % raised hardness from 0.056 N to 0.391 N, and decreased TSI from 0.83 to <0.15, indicating substantial enhancement in gel strength and stability. Rheological evaluations revealed that all bigels exhibited shear-thinning behavior, with BW-based bigels showing stronger viscoelastic properties than SIT-based ones. Thermal and crystallization studies further demonstrated that beeswax contributed to higher crystallinity, more thermally stable polymorphs, and BW-bigels showed a steep SFC decline from 20 °C to 40 °C, enhancing oral meltability while maintaining structure at refrigeration temperatures. Overall, beeswax showed greater efficacy than β-sitosterol in improving the structural and functional characteristics of ILBs, supporting its potential as a fat-structuring component in the development of reduced-fat spreadable systems. Sensory studies are needed to validate consumer acceptance in margarine-like spreadable products. Further studies are warranted to evaluate product stability and sensory attributes in real food applications.