Microencapsulation of Probiotics in Polymeric Microgels: Enhanced Viability and Stability through Inorganic Nanoparticle Doping.

This research seeks to improve the viability and stability of Lactobacillus rhamnosus by microencapsulating it in polymeric microgels doped with magnesium oxide (MgO) nanoparticles. The main aim was to explore the ability of MgO-doped sodium alginate microgels to enhance the resistance of the probiotic under gastrointestinal and refrigeration conditions. Microgels were prepared by emulsification method with sodium alginate (2% w/v) and cross-linked with 2% w/v calcium chloride, whereas MgO nanoparticles were added at levels between 0.5 and 2% (w/v). The use of MgO was based on its established antimicrobial shielding, cold storage stability, and bioadhesive characteristics that can enhance encapsulation efficiency and cell survivability. Characterization of composite microgels was conducted; SEM analysis indicated that the prepared microgels had a uniform morphology with uniform particle sizes and a smooth surface, indicating successful encapsulation and structural development. FTIR spectroscopy assured the existence of typical functional groups and molecular interactions between the MgO nanoparticles and polymer matrix, verifying efficient chemical stability and encapsulation. These compositional and structural assurances validate the integrity and effectiveness of the developed microgels for targeted probiotic delivery. In vitro digestion assays showed a notable improvement in survivability of probiotics for encapsulated cells (8.64 ± 0.23 log CFU/ml) as opposed to free cells (5.98 ± 0.14 log CFU/ml) after 120 min under gastrointestinal simulated conditions. In addition, thermal stability analysis showed that Mg(OH)₂, sodium alginate, and CaCl₂ microgels maintained probiotic viability (7.3 ± 0.20 log CFU/ml) under refrigerated storage for up to 28 days. Encapsulation of Lactobacillus rhamnosus in Mg(OH)₂-doped polymeric microgels enhanced viability under simulated gastrointestinal conditions. This improvement is attributed to the buffering capacity of Mg(OH)₂ and its role in strengthening microgel integrity for better protection. These results show the uniqueness of MgO-doped microgels in enhancing both short-term and long-term viability of probiotic encapsulates with potential applications in functional food preparations.