Kombucha Fermentation With Dried Starter Cultures: A Strategy for Microbial Stabilization via Spray and Freeze Drying

Kombucha production relies on complex microbial consortia, which often vary across batches, posing challenges for fermentation reproducibility, product standardization, and industrial scalability. This study explored the effects of spray drying (SD) and freeze drying (FD) on the viability and metabolic activity of kombucha starter cultures, using maltodextrin (MD) and gum Arabic (GA) as drying carriers. The dried starter cultures exhibited favorable physicochemical properties, including low moisture content (2.22 - 3.62%), reduced water activity (0.135 - 0.230), and high solubility (> 90%). Fermentation performance varied according to the drying method and carrier used. Acetic acid concentrations in beverages fermented with dried cultures ranged from 1.49 to 2.67 g/L, with the lowest values in the MD-SD treatment, suggesting thermal damage to microbial cells. In contrast, GA effectively protected microorganisms, as indicated by comparable acid production and minimal reductions (<1 log CFU/mL) in viable cell counts between GA-SD and GA-FD treatments. Ethanol concentrations ranged from 1.84 to 2.67 g/L, with no significant differences among treatments. Total phenolic content ranged from 271.32 to 391.47 mg GAE/L, with higher values observed in beverages fermented with freeze-dried cultures, corresponding to enhanced antioxidant activity. These findings confirm the feasibility of producing kombucha starter cultures in a dried form, offering a potential avenue for microbial stabilization and industrial process standardization. PRACTICAL APPLICATIONS: This research demonstrates that kombucha starter cultures can be effectively dried using spray-drying or freeze-drying techniques, preserving their microbial viability and fermentation capabilities. These stable, dry cultures can be easily stored, transported, and reactivated, offering a practical solution for the industrial production of kombucha and other fermented beverages.