Microbiological and physicochemical dynamics during black tea kombucha fermentation and their association with Salmonella Enteritidis survival.

چکیده اصلی

Kombucha tea, a fermented beverage, is widely consumed and gaining global popularity for its perceived functional properties. The kombucha microbial community comprises bacteria and yeast that can produce antimicrobial metabolites during fermentation, thereby suppressing foodborne pathogens. However, this aspect of kombucha's functionality remains only partially characterized under controlled conditions. This study, therefore investigated the survival of Salmonella Enteritidis (S. Enteritidis) and the associated physicochemical parameters during 14 days of black-tea kombucha fermentation. The study also assessed changes in the indigenous microbiota responsible for fermentation over the 14-day fermentation period. Kombucha was prepared using 1.6% (w/v) black tea, 10% (w/v) sucrose, and a commercially available starter culture. The kombucha was inoculated with 7.2 log CFU/mL of S. Enteritidis and fermented at room temperature for 14 days. Pathogen populations, lactic acid bacteria (LAB), total yeast and mold (TYM) counts, pH, titratable acidity, and total phenolic content were monitored over 14 days. The initial S. Enteritidis population (7.24 ± 0.44 log CFU/mL) decreased significantly (p < 0.05) by 5 log on day 10 (2.01 ± 0.1 log CFU/mL) and continued to reduce to 1.4 ± 0.3 log CFU/mL by day 14, whereas the S. Enteritidis population in the black tea increased and remained stable throughout the incubation. The inactivation of S. Enteritidis coincided with increased titratable acidity, reduced pH, and increased total phenolic content. Growth in the populations of LAB and TYM increased, corresponding to acidification and associated with the inhibition of pathogens. Results from this study demonstrate that kombucha fermentation can suppress S. Enteritidis, thereby substantially reducing pathogen growth and the risk of foodborne illness.

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