Stability, printability, and postprocessing of low oil emulsion gels for 3D printing: Effect of guar gum, locust bean gum, and oil concentration

• Hydrocolloids enhance emulsion gel printability applying 0.20% guar gum and 0.50% locust bean gum • Oil exceeding 10% increased emulsion instability by insufficiency of emulsifier • Printability properties enhanced by new hydrophilic interactions in emulsion gel • Postprocessing by baking retains structure achieving minimal dimensional deviation Emulsion gels play a crucial role in 3D/4D printing technologies. Although many studies have investigated hydrocolloids to improve the physical properties of emulsion gels with high oil concentrations (>50%), research on low-oil systems remains scarce. Their printability, as well as critical aspects such as thermal processing stability and microstructure regulation after 3D printing, are largely unexplored. This study aimed to evaluate locust bean gum (LBG) (0.50%, 0.75%, and 1.00%) and guar gum (GG) (0.05%, 0.20%, and 0.50%), along with soybean oil (SO) concentrations (10%, 15%, and 20%), on the rheological and textural properties, printability, and postprocessing (baking and microwaving) of 3D printed emulsion gels. The results showed that increased hydrocolloid concentration significantly improved the apparent viscosity, storage modulus (G′), and loss modulus (G′’). Stability increased as hydrocolloid concentration rose and oil concentration decreased, enhancing hardness and reducing adhesiveness while maintaining low dimensional deviation (< 10%) and improving 3D print quality. Printability was enhanced due to new hydrophilic interactions in the emulsion gel. Baking proved to be more effective in maintaining the structural stability of printed gels, resulting in increased hardness and minimal adhesiveness. These findings highlight that incorporating LBG and GG at low SO concentrations produced stable figures for 3D printing, with GG being more suitable for high-quality stable applications. This effect is likely due to GG's higher D-mannosyl:D-galactosyl ratio (2:1), which promotes non-covalent interactions with lentil protein and starch, leading to a denser network structure.