Development and characterization of food-grade bigel system for 3D printing applications: Role of oleogel/hydrogel ratios and emulsifiers

This study objected to widen the knowledge and applications of bigels by constructing food bigels for 3D printing. A serious of bigels were developed by incorporating a candelilla wax-based oleogel into a gelatin hydrogel at different oleogel/hydrogel ratios of 3:7, 5:5, and 7:3 under the presence of different emulsifiers (PGPR, monoglycerides and lecithin). And the influence of different oleogel/hydrogel ratios and emulsifiers on the physical properties and 3D printability of resulting bigels were studied. Bigels containing monoglycerides or lecithin could form homogenous, stable gel system with bicontinuous emulsion structure. Microstructure analysis found that PGPR could disturbed the crystalline process of candelilla wax resulting in weak mechanical strength of resulting oleogel and phase separation of bigels. These bigels exhibited shear-thinning behavior and improved mechanical properties (apparent viscosity, storage modulus, hardness, etc.) compared to pure oleogel and pure hydrogel. Bigels containing monoglyceride with oleogel/hydrogel ratio of 7:3 exhibited suitable mechanical properties for 3D printing. The results from this study indicated that 3D printable bigels could be obtained by combining candelilla wax (organogelators) with gelatin (hydrogelator), and the physical, printing properties of these bigels could be tailored by adjusting oleogel/hydrogel ratios and using different emulsifiers.