Table 3.
The effects of extraction cycles on system responses at extraction temperature 130 °C and at extraction time 10 min
| Cycles* | TPC (mg GAE/g sample) | EC50 (g sample/g DPPH) | TEAC (mg TEAC/g sample) | Menthol (mg/g sample) | Menthone (mg/g sample) |
|---|---|---|---|---|---|
| 1st | 47.79 ± 4.39c | 1.22 ± 0.13a | 110.2 ± 2.3d | 5.74 ± 1.05c | 2.29 ± 0.38c |
| 2nd | 11.31 ± 0.11b | 7.57 ± 1.00b | 17.3 ± 1.8c | 4.55 ± 0.84bc | 2.07 ± 0.07bc |
| 3rd | 4.13 ± 0.23ab | 19.00 ± 0.97c | 4.7 ± 2.6b | 2.81 ± 0.20ab | 1.38 ± 0.19b |
| 4th | 2.62 ± 0.14a | 36.23 ± 1.35d | 2.2 ± 0.5ab | 1.18 ± 0.38a | 0.52 ± 0.07a |
| 5th | 1.63 ± 0.15a | 55.35 ± 6.58e | 1.4 ± 0.1a | 0.33 ± 0.01a | 0.23 ± 0.11a |
The values are expressed as means ± standard deviations of 3 replicates. Different letters in the same column indicate significant differences (p < 0.05). TPC, total phenolic content by Folin-Ciocalteu’s reagent; EC50, the amount of sample to decrease the initial DPPH concentration by 50%; TEAC, trolox equivalent antioxidant capacity; GAE, Gallic acid equivalent
*For first cycle, peppermint was extracted with water at 130 °C for 10 min and the resulting extract was collected. The same extraction conditions were applied for 2nd, 3rd, 4th, and 5th cycles by feeding fresh water into the same extraction cell containing peppermint from previous cycle. Five extracts were independently collected and analyzed