Table 6.
Optimum experimental conditions for improved recovery of TPC, TFC, CTC, AA-TEAC from hazelnut involucre extracts.
| Parameters | TPC | TFC | CTC | AA-TEAC |
|---|---|---|---|---|
| Stirring time (min) | 3 | 3 | 3 | 3 |
| pH | 3 | 3 | 3 | 3 |
| Water in solvent (%) | 50 | 50 | 50 | 50 |
| Predicted | 345.96 | 38.41 | 269.67 | 1253.09 |
| Determined | 370.42 | 41.97 | 279.30 | 1291.22 |
| Bias (%) | 7.07 | 9.26 | 3.57 | 3.04 |
TPC: Total phenolic content expressed as mg GAE/g dw = gallic acid equivalents per dry weight of hazelnut involucre; TFC: Total flavonoid content expressed as mg QE/g dw = quercetin equivalents per dry weight of hazelnut involucre; CTC: Condensed tannin content expressed as mg CE/g dw = catechin equivalents per dry weight of hazelnut involucre; AA-TEAC: Antioxidant activity by TEAC assay expressed as mg TE/g dw = Trolox equivalents per dry weight of hazelnut involucre.