Optimizing stability and controlled release of co-encapsulated probiotics and vitamin B12 using fluidized bed coating: impact of plasticizers on tailored HPMCAS-coated granules

Probiotics and vitamins face substantial challenges in preserving their viability and stability during processing, storage, and gastrointestinal transit. This study aimed to develop co-encapsulated formulations comprising <i>Lactiplantibacillus plantarum</i> JYLP-326 and vitamin B₁₂ (vitB₁₂) using a fluidized bed coating. The coatings used included a single hydroxypropyl methylcellulose acetate succinate (HPMCAS) and two composite HPMCAS systems incorporating either the hydrophilic triacetin (TR) or lipophilic oleic acid plasticizer. The physicochemical properties of the HPMCAS films were modulated by the inclusion of different plasticizers, thereby influencing the performance of the coated granules. The fluidized bed-coating process effectively preserved probiotic viability and vitB₁₂ stability. The integration of TR into HPMCAS enhanced the pH-responsive controlled release by reinforcing the hydrogen bonding network. This feature resulted in only 3.3 % of vitB₁₂ released in simulated gastric fluid and 94.7 % released in simulated intestinal fluid, while maintaining probiotic viability at over 95 % survival. All coated granules demonstrated high probiotic survival rates, exceeding 97 %, during a 10-day storage period at 4 °C and 25 °C, although the presence of plasticizers reduced thermal resistance at 40 °C. This study demonstrates that HPMCAS-based fluidized bed coating, optimized with specific plasticizers, represents an effective approach for encapsulating sensitive bioactive components while preserving their functional efficacy throughout manufacturing, storage and consumption. The extensive data obtained in this study offer a basis for established strategies aimed at developing oral fortified foods that enhance stability and facilitate controlled release.