SPRAY-DRIED MICROPARTICLES BASED ON BACTERIAL CELLULOSE AND INULIN FOR THE CO-ENCAPSULATION OF Lactiplantibacillus plantarum AND UVAIA (Eugenia pyriformis Cambess.) PHENOLIC COMPOUNDS

Microencapsulation is a promising strategy for protecting bioactive ingredients sensitive to processing conditions, such as probiotics and phenolic compounds. This study developed microparticles obtained by spray drying based on bacterial cellulose (BC) and inulin, containing Lactiplantibacillus plantarum LP90 and phenolic extract from uvaia (Eugenia pyriformis Cambess.). The BC suspension was prepared by mechanically defibrillating 40 g of micronized BC in 4 L of Milli-Q water using a disk ultra-refiner. Six formulations were developed: 3A (25% BC at 1% w/v + 0.5% inulin w/w), 3B (25% BC + 1.0% inulin), 3C (25% BC + 1.5% inulin), 3D (25% BC + 2.0% inulin), 3E (25% BC), and 3F (2% inulin). All formulations received 20 mL of probiotic suspension (3.67x10⁹ CFU/mL) and 4 mL of phenolic extract from uvaia pulp. Drying was performed using a spray dryer at an outlet temperature of 70 °C, with a feed rate of 0.4 L/h and an air flow rate of 1.4 m³/L. Bacterial viability, total phenolic content (TPC), antioxidant capacity (ABTS), thermal stability (TGA), structural characteristics (FTIR), and α-glucosidase inhibition were evaluated. Viability ranged from 7.63 to 10.05 log CFU/g, with the highest value observed in 3A, which contained the lowest concentration of inulin (0.5%). Formulation 3F showed the lowest bacterial count, suggesting that differences in CFU/g may partly reflect dilution from increasing inulin proportions within the formulation matrix. TPC ranged from 2.29 to 6.33 mg GAE/g, with the highest value observed in 3E. Increasing the proportion of inulin reduced the phenolic content per gram, likely due to a dilution effect caused by the higher inulin content. Antioxidant capacity ranged from 6.00 to 17.16 mmol TE/g, with 3A showing the highest value among the formulations containing both polymers (12.62 mmol TE/g). The highest α-glucosidase inhibition was observed for 3E (IC₅₀ = 4.97 mg/mL), followed by 3A (IC₅₀ = 8.06 mg/mL), consistent with their higher TPC and antioxidant capacity. TGA indicated greater thermal stability for 3E, with a pronounced degradation event around 260 °C and a residue of 31% at 600 °C. FTIR analysis showed no evidence of new functional groups but suggested intermolecular interactions, particularly hydrogen bonding, with greater intensity in the 3300-3400 cm^-1 region for 3E. Thus, differences in L. plantarum LP90 counts may partly reflect the relative proportion of microorganisms to total solids as inulin increased. BC formulations also retained phenolic compounds and their antioxidant and α-glucosidase inhibitory activities, with BC alone showing the highest retention. Thus, BC-based systems may combine probiotic delivery with phenolic bioactivity, supporting multifunctional microencapsulated systems for functional foods. These findings highlight BC as a versatile, bioactive delivery matrix.

David de Paulo Farias acknowledges the São Paulo Research Foundation (FAPESP, Brazil) for financial support (Grant #2024/08062-0).