Double encapsulation with porous starch and cellulose: A strategy for enhanced probiotic protection in microcapsules...

Maintaining probiotic viability during tablet manufacturing and storage remains a critical challenge in functional food development. In this study, a double-layer microencapsulation system was developed using porous starch (PS) as the core carrier and cellulose derivatives (microcrystalline cellulose, MCC; hydroxypropyl cellulose, HPC; and hydroxypropyl methylcellulose, HPMC) as coating materials to enhance probiotic protection and tableting performance. Among the formulations, PS-HPMC presented the highest encapsulation efficiency, which was ascribed to the formation of a compact coating structure. The double-layer microcapsules significantly improved the stress resistance of Lactobacillus plantarum. In particular, the PS-HPMC system showed viability losses of 0.07 log CFU/g under acidic conditions and 1.97 log CFU/g under bile salt treatment, and it retained a survival rate of 44.09% after tablet compression. In vitro gastrointestinal digestion revealed a controlled release profile of probiotics, which followed the Korsmeyer-Peppas model. A viable count of 6.67 log CFU/g was maintained after digestion, demonstrating effective protection of probiotics during gastrointestinal transit. In addition, PS-HPMC tablets preserved 10.80 ± 0.02 log CFU/g after 30 days of storage at 4 °C, and the predicted shelf life based on the first-order kinetic model reached 202.6 days, indicating the double-layer structure enhanced storage stability and prolonged shelf life. The prepared tablets also exhibited satisfactory mechanical strength and disintegration properties. Overall, the cellulose-coated porous starch system effectively enhanced the viability and stability of probiotics in solid dosage forms, providing a promising strategy for the development of functional foods.