Enhancing the stability of lutein by loading into dual-layered starch-ethyl cellulose gels using 3D food printing

The goal of this project was to increase the stability of lutein by its encapsulation into starch-ethyl cellulose (EC) gels using 3D printing with a coaxial nozzle setup. Coaxial extrusion 3D printing was implemented by using lutein-loaded EC as the inner flow (core) material and corn starch paste as the outer flow (shell) material. The effects of layer height (0.4, 0.7, and 1 mm), EC (6 %, 8 %, and 10 % w/v) and starch (9 %, 10 %, 11 %, and 12 %, w/w) concentrations, and printing temperature (55, 65, or 75 °C) were investigated. As observed from the microCT images, the layer height of 0.7 mm provided the best printability. The samples fabricated using 10 % and 11 % starch concentrations at printing temperatures of 55 and 65 °C, respectively, demonstrated the best shape fidelity and storage stability. Specifically, the 3D-print of 10 % starch at 55 °C with 10 % EC provided the highest lutein stability as a result of the improved shape integrity at this printing condition. The 3D-printed sample at the optimized conditions yielded significantly higher lutein retention indexes of ∼70 % and 48 % after 21 days of storage at 25 °C and 50 °C, respectively, compared to the unencapsulated physical mixture of crude lutein (24 % and 10 %, respectively) at the same storage conditions. The developed dual-layered starch-EC encapsulation approach via 3D printing serves as a platform technology for loading bioactive compounds into food formulations with improved stability.