Influence of Herbal Additives on the Physicochemical, Microbiological, Polyphenolic, and Sensory Profile of Green Tea-Based Kombucha

Kombucha is a functional beverage with growing popularity due to its health-promoting properties. This study aimed to evaluate the impact of herbal infusions on the quality of green tea-based kombucha. Four variants were prepared: a control (K1) and three experimental samples combining 70% green tea with 30% (v/v) Mentha spicata (K2), Hibiscus sabdariffa (K3), or Clitoria ternatea (K4). Fermentation lasted four days at 24 ± 1 °C. Physicochemical parameters, polyphenol profile (HPLC), microbiological safety, and sensory quality were assessed using QDA and electronic tongue analysis. K3 showed the highest polyphenol content (291 mg/L), especially catechins. K4 achieved the highest overall sensory quality due to its fruity aroma, balanced sweet-sour taste, and favorable microbiological profile. K2 had the lowest caffeine content (114 mg/L) and a distinct minty flavor. All samples were microbiologically safe. Herbal additives influenced fermentative microbiota: K3 had fewer acetic acid bacteria, while K4 had the highest lactic acid bacteria count. Electronic tongue analysis confirmed sensory panel results and revealed distinct taste profiles among the variants. Herbal infusions significantly enhance the nutritional and sensory properties of kombucha. Their use offers a promising strategy for developing functional beverages with tailored characteristics.