Individual Presentation: A Novel Approach Based on 3D Food Printing for the Delivery of Probiotics

This study presents the development of a 3D food printing (3DFOODP) system incorporating a starch and alginate-pectin-based core-shell structure for pH-sensitive release of probiotics. A spiral cube (30x30x5 mm) was designed digitally and printed using a coaxial nozzle to produce a core (starch)-shell (alginate-pectin) structure. The printing parameters (i.e., ink concentrations, printing pressure, and printing temperature) were optimized. The rheological properties (including viscosity, recovery, and storage-loss moduli) of the gel solutions were assessed before printing. The 3D-printed hydrogels were characterized using FTIR, XRD, and SEM. The release profiles of a model bioactive compound, methylene blue (MB), from 3D-printed samples were determined in simulated gastric and intestinal fluids (SGF and SIF). In addition, the survival of Bifidobacterium bifidum was determined upon encapsulation into the 3D-printed hydrogel system. Optimal conditions for 3DFOODP were determined as 11 wt.% starch for the core and 2 wt.% alginate-pectin with 0.02M CaCl2 for the shell, printed at 95°C and 23°C, respectively. The MB release from the 3D-printed matrix in SGF (25%) was significantly lower compared to crude MB under the same conditions (89%), protecting the loaded compounds in acidic environments (i.e., stomach). The pH-sensitive Al-P shell effectively protected probiotics in SGF, with 83.1% survival after 2 h, compared to the complete elimination of unencapsulated bacteria. This study highlights the potential of coaxial 3DFOODP to create innovative hydrogel systems for targeted delivery of pH-sensitive nutrients.