Table 3.
Predicted and verified optimal sample characteristics.
| Factor | Ultra-Turrax Pretreatment | Ultrasound-Assisted Pretreatment | ||
|---|---|---|---|---|
| Predicted Value | Verified Value | Predicted Value | Verified Value | |
| X1 | 29,999.9 rpm | 30,000 rpm | 0.875 g | 0.875 g |
| X2 | 0.849 g | 0.849 g | 77.7% | 78% |
| X3 | 54.0% | 54% | 21.7 min | 22 min |
| X4 | 89.9 s | 90 s | 68.8 °C | 70 °C |
| TPC (mg GAE/g dry spent grain) | 1.40 ± 0.13 | 1.37 ± 0.11 | 1.44 ± 0.19 | 1.42 ± 0.15 |
| TFC (mg QE/g dry spent grain) | 1.36 ± 0.13 | 1.34 ± 0.15 | 1.29 ± 0.15 | 1.25 ± 0.11 |
| DPPH (%Inhibition) | 54.75 ± 4.85 | 54.77 ± 3.75 | 74.13 ± 5.03 | 74.20 ± 4.39 |
TPC: total polyphenol content, TFC: total flavonoid content, DPPH: scavenging 2, 2-diphenyl-1-picrylhydrazyl free radical activity.