Generation of pH-responsive starch and alginate-pectin hydrogels using coaxial 3D food printing: The release of methylene blue
Que-Anh Truong-Le, Matthias D.R. Lenie, Ali Ubeyitogullari
Abstract
This article presents the development of a 3D food printing (3DFOODP) system incorporating a core-shell structure to encapsulate a model compound, methylene blue (MB). A coaxial nozzle configuration was employed to fabricate 3D-printed samples, featuring a starch core and a pH-responsive alginate-pectin (Al P) shell. The optimal 3D printing conditions were determined as 11 wt% starch as the core along with 2 wt% Al P with 0.02 M CaCl 2 as the shell at printing temperatures of 95 °C and ambient temperature (23 °C), respectively. The overall 3D printability at this condition was 98 %, closely matching the digital 3D design. The rheological experiments were performed to evaluate the food inks' viscosity, viscoelastic properties, and recovery behavior. The morphology, crystallinity, and chemical structure of the samples were also investigated. The release of MB from the 3D-printed matrix was determined in simulated gastric (pH 1.2) and intestinal (pH 6.8) fluids, where 25 and 55 % of encapsulated MB was released after 1 h at these conditions, respectively. However, crude MB showed significantly higher releases in simulated gastric (89 %) and intestinal (78 %) fluids after 1 h. The significant difference in the release rate constants (i.e., 0.0077 for encapsulated MB and 0.4752 for crude MB) in simulated gastric fluids also supported the controlled release of MB once loaded in the 3D-printed gel matrix. Therefore, the developed innovative 3D printing encapsulation approach can provide a pH-sensitive release of potential bioactive compounds (BCs).