Valorization of Citrus limetta peel powder for probiotic encapsulation: enhanced gastrointestinal and storage stability of Lactiplantibacillus plantarum RAD1 isolated from fermented radish (Raphanus sativus L.).

Probiotics offer significant health benefits when consumed in adequate amounts; however, their viability is often compromised during processing, storage, and transit through the gastrointestinal tract, which limits their effectiveness in functional food applications. In the present study, seventeen indigenous LAB strains were isolated from fermented radish, among which six strains showed potential probiotic characteristics. The strain revealed to have the most desirable probiotic attributes was identified as Lactiplantibacillus plantarum, as confirmed by 16 S rRNA gene sequencing. Further, we assessed the viability and stability of L. plantarum RAD1 under simulated gastrointestinal conditions and in pasteurized mosambi juice after encapsulation with alginate and Citrus limetta peel powder (CLPP). The alginate beads (Alg) and CLPP-coated Alg beads (Alg@CLPP) were characterized by SEM and FTIR to evaluate the size, morphology, and interaction between the bacteria and wall materials. The Alg@CLPP beads showed a satisfactory encapsulation efficiency of around 96.07% and significantly improved cell viability in simulated gastric fluids compared to free cells. The viability of free and encapsulated L. plantarum RAD1 was also studied in pasteurized mosambi juice, and physicochemical characterization of the juice was performed in terms of pH and titratable acidity over 28 days of storage at 4℃. The CLPP-coated beads revealed a protective effect on RAD1, enhancing its survival in fruit juice under storage conditions. In conclusion, this study presents a formulation for encapsulating probiotics as dietary supplements, aiming to promote human health benefits while also proposing an innovative approach to valorizing agricultural by-products, thereby addressing food waste while contributing to the development of sustainable, health-oriented dietary supplements.