Preparation and Analysis of Physicochemical Properties, Antioxidant and Antibacterial Activities of Kombucha Tea Produced from Beijing Bamboo Leaf Tea (Dendrocalamus sp.) and Green Tea

Beijing bamboo (Dendrocalamus sp.), belonging to the Poaceae family, has been largely neglected and underutilized, particularly its leaves. This study aims to investigate the physicochemical properties, antioxidant, and antimicrobial activities of Beijing bamboo leaf and Beijing bamboo leaf kombucha. Hot air drying was conducted at temperatures of 60, 65, and 70ºC, with results indicating that 65ºC is the optimal drying temperature for achieving the highest levels of total phenolic compounds, flavonoids, and antioxidant activities. Beijing bamboo leaf tea underwent a 21-day fermentation process with a kombucha consortium comprising yeasts and acetic acid bacteria. The results showed that the changing trends of pH, total acidity, and total soluble solids were similar between kombucha produced from Beijing bamboo leaf tea and green tea. Fermentation notably enhanced the antioxidant activity of the kombucha, as evidenced by DPPH and FRAP assays, which correlated with increases in phenolics and flavonoids. The antimicrobial efficacy was assessed through the agar diffusion method and minimum inhibitory concentration (MIC), revealing that both Beijing bamboo leaf tea and green tea suppressed the growth of pathogenic bacteria, including Salmonella Typhimurium DMST 562, E. coli DMST 4242, Bacillus cereus DMST 5040, Staphylococcus aureus DMST 8840, and Pseudomonas aeruginosa DMST 4739. Notably, kombucha from green tea exhibited superior antimicrobial effects compared to Beijing bamboo leaf tea kombucha. Additionally, fermentation of Beijing bamboo leaf tea resulted in higher counts of yeast, acetic acid bacteria, and lactic acid bacteria throughout the fermentation process than those observed in green tea kombucha. These findings highlight the potential of Beijing bamboo leaves as a valuable resource for developing functional properties in underutilized plant resources, offering promising applications in the food and health industries.