Cellulose-derivative based bigels: stability and printability assessment for extrusion-based 3D printing

Reliable formulation of food-grade bigels that remain stable and can be smoothly extruded through a direct-ink-writing (DIW) nozzle is a critical hurdle preventing personalised nutrition, where DIW 3D printing can enable customised shapes and dose-controlled, multi-component food items on demand. This study optimises and mechanistically explains the stability–printability balance of carboxymethyl-cellulose (CMC) - ethyl-cellulose (EC) bigels, targeting advanced applications such as co-delivery of hydrophilic and lipophilic bioactives. CMC hydrogel (6 ) and EC oleogel (15 ) were blended at various ratios ( , , , ) alongside single-phase controls. The microstructure of bigels was characterised using microscopy, FTIR, and XRD. Physical stability, mechanical properties, and DIW 3D printability were also evaluated. The results showed that all formulations exhibited solid-like and shear-thinning behaviour ( , rapid thixotropic recovery) and remained free of syneresis or phase separation for at although freeze–thaw resistance decreased with higher oleogel fractions. Increasing EC content enhanced hardness, gel strength and crystallinity. The bigel delivered the best compromise between extrusion flowability and post-printing structural integrity, producing high-fidelity constructs with minimal distortion. Overall, tailoring the ratio of EC and CMC enabled bigels with robust mechanical properties, excellent stability, and high-fidelity 3D printability. These findings highlight the promise of EC–CMC bigels as delivery systems for food applications, offering a versatile platform for personalised nutrition, bioactive encapsulation, and fat-replacement strategies in health-oriented product development. • •Cellulose derivative-based bigels (CMC–EC) demonstrated excellent stability and tailored printability for bioactive delivery applications. • Increasing ethyl cellulose (EC) content improved mechanical strength, crystallinity, and printability but reduced freeze–thaw stability. • Bigels exhibited solid-like, shear-thinning, and rapid thixotropic recovery behaviours ideal for direct-ink-writing (DIW) 3D printing. • A balanced oleogel–hydrogel ratio (6:4) optimised extrusion flowability and post-printing structural integrity for high-fidelity 3D constructs. • EC–CMC bigels offer promising potential as versatile delivery platforms for personalised nutrition, bioactive encapsulation, and/or fat replacement.