Enhanced Survival of Probiotics by Encapsulating in Hydrogel Beads Based on Sodium Alginate/Pectin/Tannic Acid

Probiotics as functional foods show weak resistance to stress, and polysaccharide-based hydrogel protects probiotic viability. In the present study, we designed a novel delivery system for Christensenellaceae minuta (C. minuta) using sodium alginate (SA), pectin (PEC), and tannic acid (TA) in two ways. In the first method (Hydrogel-a), all of the materials were mixed simultaneously. In the second method (Hydrogel-b), the bacteria were first coated with TA, followed by encapsulation in hydrogel beads composed of SA and PEC. Both methods achieved a bacterial encapsulation efficiency of up to 98%. Encapsulated C. minuta exhibited significantly higher survival rates compared to bare C. minuta under heat stress (4.6-fold in both hydrogels), freeze-drying (6.5-fold in Hydrogel-a and 7.0-fold in Hydrogel-b), harsh gastrointestinal conditions (56.7-fold in Hydrogel-a and 68.1-fold in Hydrogel-b), and extended storage stability (4.9-fold in both hydrogels). Hydrogen bonds and an amorphous structure were formed in both hydrogels. Hydrogel-b delivered the most pronounced therapeutic effects in colitis. However, the abundance of C. minuta was similar between the two encapsulated C. minuta groups. This research provides critical advancements in efficient microbial delivery systems and extends applications in both the biopharmaceutical and food industries.