Table 1.
Impact of thermal treatments on the total phenolic (a) and total flavonoid (b) contents and different antioxidant activities (c–f) of the selected Brassica vegetables.
| Source | Type III Sum of Squares | df | Mean Square | F | Sig. | Observed Power |
|---|---|---|---|---|---|---|
| a: Total phenolic content (TPC) | ||||||
| Corrected Model | 221.145 | 19 | 11.639 | 699.000 | <0.001 | 1.000 |
| Intercept | 110.157 | 1 | 110.157 | 6615.546 | <0.001 | 1.000 |
| Veg | 14.429 | 4 | 3.607 | 216.633 | <0.001 | 1.000 |
| Treatment | 181.493 | 3 | 60.498 | 3633.225 | <0.001 | 1.000 |
| Veg × Treatment | 25.223 | 12 | 2.102 | 126.232 | <0.001 | 1.000 |
| Error | 0.666 | 40 | 0.017 | |||
| Total | 331.969 | 60 | ||||
| Corrected Total | 221.811 | 59 | ||||
| R2 = 0.997 (Adjusted R2 = 0.996); level of significance: 0.05 | ||||||
| Corrected model for TPC = Intercept + Veg + Treatment + Veg × Treatment | ||||||
| b: Total flavonoid content (TFC) | ||||||
| Corrected Model | 29,157.237 | 19 | 1534.591 | 169.805 | <0.001 | 1.000 |
| Intercept | 29,577.335 | 1 | 29,577.335 | 3272.772 | <0.001 | 1.000 |
| Veg | 4207.408 | 4 | 1051.852 | 116.389 | <0.001 | 1.000 |
| Treatment | 19,693.546 | 3 | 6564.515 | 726.373 | <0.001 | 1.000 |
| Veg × Treatment | 3678.639 | 12 | 306.553 | 33.921 | <0.001 | 1.000 |
| Error | 316.309 | 35 | 9.037 | |||
| Total | 63,114.012 | 55 | ||||
| Corrected Total | 29,473.545 | 54 | ||||
| R2 = 0.989 (Adjusted R2 = 0.983); level of significance: 0.05 | ||||||
| Corrected model for TFC = Intercept + Veg + Treatment + Veg × Treatment | ||||||
| c: Ferric reducing antioxidant power (FRAP) | ||||||
| Corrected Model | 0.654 | 19 | 0.034 | 1475.981 | <0.001 | 1.000 |
| Intercept | 0.668 | 1 | 0.668 | 28,620.643 | <0.001 | 1.000 |
| Veg | 0.051 | 4 | 0.013 | 549.750 | <0.001 | 1.000 |
| Treatment | 0.555 | 3 | 0.185 | 7926.548 | <0.001 | 1.000 |
| Veg × Treatment | 0.048 | 12 | 0.004 | 172.083 | <0.001 | 1.000 |
| Error | 0.001 | 40 | 2.333 × 10−5 | |||
| Total | 1.323 | 60 | ||||
| Corrected Total | 0.655 | 59 | ||||
| R2 = 0.999 (Adjusted R2 = 0.998); level of significance: 0.05 | ||||||
| Corrected model for FRAP = Intercept + Veg + Treatment + Veg × Treatment | ||||||
| d. 2,2-diphenyl-1-picrylhydrazyl (DPPH) activity | ||||||
| Corrected Model | 4.075 | 19 | 0.214 | 825.807 | 0.000 | 1.000 |
| Intercept | 21.799 | 1 | 21.799 | 83,943.365 | 0.000 | 1.000 |
| Treatment | 2.676 | 3 | 0.892 | 3434.287 | 0.000 | 1.000 |
| Veg | 0.859 | 4 | 0.215 | 826.851 | 0.000 | 1.000 |
| Treatment × Veg | 0.540 | 12 | 0.045 | 173.339 | 0.000 | 1.000 |
| Error | 0.010 | 40 | 0.000 | |||
| Total | 25.884 | 60 | ||||
| Corrected Total | 4.085 | 59 | ||||
| R2 = 0.997 (Adjusted R2 = 0.996); level of significance: 0.05 | ||||||
| Corrected model for DPPH = Intercept + Veg + Treatment + Veg × Treatment | ||||||
| e. Metal ion chelation (MIC) activity | ||||||
| Corrected Model | 0.551 | 19 | 0.029 | 97.496 | 0.000 | 1.000 |
| Intercept | 0.636 | 1 | 0.636 | 2138.872 | 0.000 | 1.000 |
| Treatment | 0.375 | 3 | 0.125 | 420.579 | 0.000 | 1.000 |
| Veg | 0.099 | 4 | 0.025 | 83.451 | 0.000 | 1.000 |
| Treatment × Veg | 0.099 | 12 | 0.008 | 27.861 | 0.000 | 1.000 |
| Error | 0.009 | 30 | 0.000 | |||
| Total | 1.167 | 50 | ||||
| Corrected Total | 0.559 | 49 | ||||
| R2 = 0.984 (Adjusted R2 = 0.974); level of significance: 0.05 | ||||||
| Corrected model for MIC = Intercept + Veg + Treatment + Veg × Treatment | ||||||
| f. 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS•+) activity | ||||||
| Corrected Model | 6.078 | 19 | 0.320 | 4.119 | 0.000 | 0.999 |
| Intercept | 1.912 | 1 | 1.912 | 24.617 | 0.000 | 0.998 |
| Treatment | 2.589 | 3 | 0.863 | 11.112 | 0.000 | 0.998 |
| Veg | 1.297 | 4 | 0.324 | 4.175 | 0.007 | 0.880 |
| Treatment × Veg | 2.176 | 12 | 0.181 | 2.335 | 0.026 | 0.887 |
| Error | 2.640 | 34 | 0.078 | |||
| Total | 10.252 | 54 | ||||
| Corrected Total | 8.718 | 53 | ||||
| R2 = 0.697 (Adjusted R2 = 0.528); level of significance: 0.05 | ||||||
| Corrected model for ABTS = Intercept + Veg + Treatment + Veg × Treatment | ||||||