*3.4. DPPH Scavenging Ability and Total Phenolic Content during Kombucha Fermentation*

The DPPH scavenging ability of kombucha prepared from green, oolong, and black tea significantly increased during the fermentation process to 2.642, 2.582, and 0.435 mg GAE/ml kombucha tea, respectively (Figure 5). The maximum increase of DPPH scavenging activity was presented after 15 days in the kombucha that was prepared from green tea. Kombucha prepared from oolong tea showed the highest DPPH scavenging activity after 9 days of fermentation and was remarkably stable after 12–15 days of fermentation. Moreover, the DPPH scavenging ability of the kombucha prepared from black tea was at the highest incremental value after 3 days of the fermentation process.

**Figure 5.** DPPH scavenging ability (**A**) and total phenolic content (**B**) during fermentation of kombucha prepared from green tea (ᶺ), oolong tea (-), and black tea (). \* The values were significantly different between the beginning of the fermentation and on each day of the fermentation period (*p* < 0.05). The results are presented as mean ± SD of three independent experiments.

Total phenolic content is shown in Figure 5. After fermentation for three days, the kombucha that was prepared from green, oolong, and black teas revealed maximum levels of total phenolic contents at 1.248, 1.011, and 0.455 mg GAE/mL kombucha tea, respectively. After 3–6 days of fermentation, the amounts of phenolic compounds decreased and then appeared to be stable at 15 days of the fermentation process. Thus, kombucha prepared from green tea revealed the highest amounts of antioxidant activity and total phenolic content.
