Multicomponent oleogels of ethylcellulose-binary waxes: atomic force microscopy observation and synergistic effect analysis

The interactions between ethylcellulose (EC) and waxes in multicomponent oleogel systems are underexplored. This study investigated the structural, functional, and physiochemical properties of rice bran oil (RBO) oleogels structured with various ratios of EC and a binary wax blend (9:1 beeswax (BW): carnauba wax (CRW)), varied in 0.5 % w/w increments at a constant total gelator concentration of 4 % w/w. All multicomponent systems formed self-sustaining oleogels at the low gelator concentration. High-resolution atomic force microscopy (AFM) revealed continuous mesh-like EC chains and their presence on the surface of wax crystals in multicomponent oleogels, suggesting co-existing structures. The oil binding capacity (OBC) of EC oleogel increased significantly from 70.92 % to 99.94 % when the binary wax ratio reached 3.5 % w/w. However, the 0.5EC3.5Wax oleogel exhibited a firmer but brittle gel (G' = 87,440 Pa, yield flow points = 0.12 and 0.39 %, respectively), whereas the 3.5EC0.5Wax oleogel significantly improved the yield and flow points (1.82 and 23.35 %, respectively) but reduced G' (4404 Pa). Temperature ramp tests revealed that higher EC ratios led to early viscoelastic structuring, followed by wax crystallisation that reinforces the final network. The highest gelation onset temperature was observed for 4EC at 94.29 °C, which decreased to 89.54 °C in 3.5EC0.5Wax, with the lowest value of 36 °C identified in the 0.5EC3.5Wax oleogel. Fourier-transform infrared (FTIR) spectroscopy confirmed that the multicomponent oleogels were physically stabilized by hydrogen bonding and van der Waals forces. X-ray diffraction (XRD) showed the presence of β' crystals; the crystallinity and plasticity increased with the binary wax ratio. These results show the potential of preparing stable solid fat substitutes using mixtures of EC and binary wax.<p></p>