3D printing of encapsulated probiotics: Effect of different post-processing methods on the stability of Lactiplantibacillus plantarum (NCIM 2083) under static in vitro digestion conditions and during storage

The increasing demand for functional foods is associated with the need to deliver probiotics through novel food matrices. In this study, a high-fiber high-protein composite flour matrix was selected as the food vehicle. To improve their stability, four encapsulation techniques (spray drying, freeze drying, spray-freeze drying, and refractance window drying) were used for the production of probiotic encapsulates in fructooligosaccharide: whey protein: maltodextrin matrix. Considering the need to develop customized/personalized products, the material supply was 3D printed using an in-house developed extrusion-based food 3D printer CARK (controlled additive-manufacturing robotic kit). The effect of four post-processing methods (freeze drying, refractance window drying, hot air drying, and microwave drying) was explored and the overall effect on probiotic stability during storage under two different conditions (4.C and room temperature) was evaluated. No significant loss of probiotic viability was observed during the 3D printing process. Freeze drying method of post-processing achieved >90% survival rate for freeze dried and spray-freeze dried synbiotics incorporated products. Among the various treatments, spray-freeze-dried synbiotics incorporation followed by freeze drying post-processed 3D printed construct showed the best survival rate (79%) and viability (6.43 +/- 0.17 log(10) CFU/ml) under static in vitro digestion conditions. With around 96-98% survival rate with retained viability of 7.98 +/- 0.48 log(10) CFU/ml during the storage period of 35 days, the approach shows promising prospects for the delivery of probiotics in prebiotic matrices of customized shapes.