The Influence of Substrate and the Origin of Symbiotic Culture of Bacteria and Yeasts on the Microbiological, Antioxidant, and Antibacterial Properties of Kombucha-like Beverages

Abstract

Kombucha is a fermented tea beverage produced using SCOBY and is recognized for its potential health-promoting properties. This study investigated the effects of fermentation substrate and the geographic origin of the SCOBY culture on the microbiological, physicochemical, antioxidant, and antibacterial properties of Kombucha and Kombucha-like beverages produced from black tea, milk, and rice. A 72 h fermentation period was selected to enable a direct comparison of SCOBY performance across the different substrates. Tea- and milk-based substrates supported greater microbial growth, with total viable counts reaching approximately 6.0–8.0 log CFU/mL, whereas the rice-based beverage showed limited microbial development. The Polish SCOBY culture produced greater acidification, with pH values ranging from approximately 3.66 to 4.36, and exhibited stronger antibacterial activity, particularly against Escherichia coli, which was the most susceptible of the tested strains. HPLC analysis revealed distinct organic acid profiles among the fermented beverages. Tea-based Kombucha contained substantial amounts of acetic, lactic, and gluconic acids and exhibited the highest antioxidant activity. Total phenolic content was positively correlated with antioxidant capacity. In contrast, the rice-based beverage showed the lowest antioxidant activity. Significant differences in microbial growth and metabolite profiles were also observed between the Polish and Italian SCOBY cultures, indicating that culture origin influenced the fermentation pathways and the resulting properties of the beverages. Overall, the findings confirm the suitability of black tea as a substrate for Kombucha fermentation. They also indicate that alternative fermentation substrates, such as milk and rice, may be used to develop fermented beverages with distinct functional characteristics, although their antioxidant potential may be lower than that of tea-based Kombucha.