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 degrees 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 degrees C, respectively, demonstrated the best shape fidelity and storage stability. Specifically, the 3D-print of 10 % starch at 55 degrees 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 similar to 70 % and 48 % after 21 days of storage at 25 degrees C and 50 degrees 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.