*2.8. Total Phenolic Content of Kombucha Tea*

Total phenolic content of kombucha tea was determined by Folin-Ciocalteu reagent [16]. Kombucha tea (250 μL) was mixed with 125 μL of 50% Folin-Ciocalteu reagent (Merck, Germany) and 250 μL of 95% ethanol. The mixture was incubated in the dark at room temperature for 5 min. Subsequently, 250 μL of 5% sodium carbonate was then added, and the mixture was incubated in the dark at room temperature for 60 min. Blue molybdenum–tungsten complex was formed and detected at 725 nm by spectrophotometer (Genesys 20, Thermo Scientific, Germany). Total phenolic content was calculated by comparing the substance to standard gallic acid and was expressed as milligrams of gallic acid per milliliter of kombucha tea (mg GAE/mL kombucha tea).
