Encapsulation of Bifidobacterium bifidum into a pH-sensitive alginate-pectin gel system using 3D food printing:...

This study developed a novel pH-sensitive delivery system based on starch and an alginate/pectin matrix to encapsulate Bifidobacterium bifidum using 3D food printing with a coaxial nozzle design. Probiotics were encapsulated into a starch gel as the core material, while alginate/pectin gel was used as the outer (shell) material during coaxial 3D printing. Rheological analyses were conducted to assess the viscosity, viscoelastic properties, and recovery behavior of the food inks. The morphology, crystallinity, and chemical structure of the 3D-printed samples were characterized. The probiotics exhibited a high survival rate of 96 % following the 3D printing process, with cell counts exceeding 10⁹ CFU/g after freeze-drying in the 3D-printed samples. In simulated gastric fluid (pH 1.2), 83.1 % of the encapsulated bacteria via 3D printing remained viable after 2 h, whereas all the unencapsulated bacteria were eliminated. In simulated intestinal fluid (pH 6.8), both unencapsulated and encapsulated bacteria demonstrated high survival rates of 93.2 % and 92.0 %, respectively. These findings provide strong evidence that this protective system effectively preserves bacterial viability in acidic conditions, and facilitates targeted delivery to the colon.