Development of a shelf-stable, gel-based delivery system for probiotics by encapsulation, 3D printing, and freeze-drying

Abstract

A novel integrated manufacturing approach of encapsulation, extrusion-based 3D printing, and freeze-drying was applied to develop a shelf-stable, convenient product that maintained the viability of probiotics. The two selected strains of probiotic organisms, including Bifidobacterium lactis and Lactobacillus acidophilus, were encapsulated at 109–1010 CFU/g within 3, 5, and 7 g/100 g alginate-gelatin (A/G) hydrogels in different A/G ratios (1/2, 1/1, and 2/1). The B. lactis cell viability exceeded 109 CFU/g after 3D printing, with less than 1 log reduction throughout the integrated manufacturing process. The viability of B. lactis was maintained at a level larger than 6 log CFU/g upon 8 weeks of storage at room temperature. While L. acidophilus showed lower viability, with 106 CFU/g after printing, and up to 2.5 log reduction by the end of the integrated manufacturing processes. After freeze-drying, the 3D-printed products changed from a semi-solid to a solid-like state, confirmed by increased hardness and decreased water activity. This study demonstrated that an integrated manufacturing consisting of encapsulation, 3D printing, and freeze-drying has the potential to produce a shelf-stable, convenient snack food or supplement product that can deliver live probiotics with customized strains and dosage.