Table 2.
Comparison of bioactive compounds at each optimization stage for the acetic acid fermentation phase in the one- and two-step fermentation processes of green tea.
| Optimization Stage (Key Factors) 1 |
One-Step Fermentation | Two-Step Fermentation | ||
|---|---|---|---|---|
| Acetic Acid (mg/L) | Acetic Acid (mg/L) | GABA (mg/L) | Lactic Acid (mg/L) | |
| Control | 282.98 ± 25.01 2,A,a (100.00%) 3 |
5250.00 ± 1578.00 A,b (100.00%) |
24.77 ± 4.83 A | 243.44 ± 58.15 A |
| First stage (fermentation alcohol) |
3818.18 ± 239.56 B,a (1349.28%) |
6011.83 ± 352.42 AB,b (114.51%) |
28.10 ± 1.91 AB | 212.63 ± 80.00 A |
| Second stage (carbohydrate) |
5362.54 ± 370.70 C,a (1895.02%) |
7400.28 ± 199.85 BC,b (140.96%) |
25.99 ± 4.27 AB | 30.33 ± 3.30 B |
| Final stage (fermentation temperature) |
5997.80 ± 513.06 C,a (2119.51%) |
8349.49 ± 418.04 C,b (159.04%) |
31.49 ± 1.17 B | 88.32 ± 9.76 B |
1 Key fermentation factors applied in each optimization stage. Optimized conditions were 3% fermentation alcohol, 8% sucrose, and fermentation at 25 °C for one-step fermentation; and 3% fermentation alcohol, 4% sucrose, and fermentation at 25 °C for two-step fermentation. The inoculated green tea without supplementation served as a control. 2 Mean ± standard deviation of independent experiments performed in triplicate. Mean values of the contents of bioactive compounds in the same column that are followed by different upper-case letters (A–C) are significantly different (p < 0.05). Mean values of acetic acid content in the same row (one-step fermentation vs. two-step fermentation) that are followed by different lower-case letters (a,b) are significantly different (p < 0.05). 3 Relative acetic acid contents are represented as the percentage with respect to the corresponding control.