Table 1.
Optimization of key parameters for phenol solvent-based extraction (SE). The solid/liquid column indicates the kgDW of used pomace in for 1 L of solvent; the liquid/solid column indicates the amount of solvent for 1 kgDW of pomace. Total phenol quantification results for each liquid extract were expressed as g of gallic acid (GA) equivalent per kg of pomace dry weight (gGAeq/kgDW) and as g of GA equivalent per litre of extract (gGAeq/L). Different letters indicate statistically significant difference (one-way ANOVA followed by post hoc two-tailed Student’s t-test, p < 0.05) among data expressed in the same measure unit. Data are the mean ± SD (n = 2). EtOH, ethanol; AcN, acetonitrile; S/L, solid/liquid ratio.
| Sample | S/L (kgFW/L) | Solid/liquid (kgDW/L) | Liquid/solid (L/kgDW) | Temperature (°C) | Time (h) | Total phenols |
|
|---|---|---|---|---|---|---|---|
| gGAeq/kgDW | gGAeq/L | ||||||
| 50% EtOH | 1:10 | 0.037 | 27.96 | 50 | 1 | 40.43 ± 2.29 a | 1.50 ± 0.08 a |
| 2 | 39.26 ± 9.53 a,b | 1.46 ± 0.35 a,b | |||||
| 4 | 46.63 ± 1.65 b | 1.73 ± 0.06 b | |||||
| 50% AcN | 1:10 | 0.037 | 27.96 | 50 | 1 | 48.61 ± 1.65 b,c | 1.80 ± 0.06 b,c |
| 2 | 46.00 ± 1.52 b | 1.71 ± 0.06 b | |||||
| 4 | 49.15 ± 0.38 c | 1.82 ± 0.01 c | |||||
| 75% Acetone | 1:10 | 0.037 | 27.96 | 50 | 1 | 47.17 ± 0.64 b | 1.75 ± 0.02 b |
| 2 | 50.13 ± 2.54 b,c | 1.86 ± 0.09 b,c | |||||
| 4 | 47.35 ± 3.94 b,c | 1.76 ± 0.15 b,c | |||||
| Water | 1:10 | 0.037 | 27.96 | 50 | 1 | 15.18 ± 0.04 d | 0.56 ± 0.01 d |
| 2 | 15.07 ± 0.57 d | 0.56 ± 0.02 d | |||||
| 4 | 13.58 ± 0.01 e | 0.50 ± 0.01 e | |||||
| 50% EtOH | 1:5 | 0.074 | 13.48 | 50 | 1 | 37.74 ± 0.64 a | 2.80 ± 0.05 f |
| 2 | 37.15 ± 1.84 a | 2.76 ± 0.14 f | |||||
| 4 | 40.03 ± 0.19 a | 2.97 ± 0.01 f | |||||
| 50% AcN | 1:5 | 0.074 | 13.48 | 50 | 1 | 39.35 ± 1.40 a | 2.92 ± 0.10 f |
| 2 | 40.84 ± 1.33 a | 3.03 ± 0.10 f | |||||
| 4 | 40.66 ± 2.60 a | 3.02 ± 0.19 f | |||||
| 75% Acetone | 1:5 | 0.074 | 13.48 | 50 | 1 | 44.61 ± 2.48 a,b | 3.31 ± 0.18 f,g |
| 2 | 46.90 ± 0.13 b | 3.48 ± 0.01 g | |||||
| 4 | 44.83 ± 2.80 a,b | 3.33 ± 0.21 f,g | |||||
| Water | 1:5 | 0.074 | 13.48 | 50 | 1 | 12.04 ± 1.93 e,f | 0.89 ± 0.14 h,i |
| 2 | 12.59 ± 0.88 e | 0.93 ± 0.07 i | |||||
| 4 | 9.47 ± 1.85 f | 0.70 ± 0.14 h | |||||
| 50% EtOH | 1:5 | 0.074 | 13.48 | 70 | 1 | 22.60 ± 0.57 g | 1.68 ± 0.04 j |
| 2 | 25.79 ± 0.01 h | 1.91 ± 0.01 k | |||||
| 4 | 28.84 ± 0.01 i | 2.14 ± 0.01 l | |||||
| 50% AcN | 1:5 | 0.074 | 13.48 | 70 | 1 | 24.80 ± 0.13 h | 1.84 ± 0.01 k |
| 2 | 26.01 ± 0.19 h | 1.93 ± 0.01 k | |||||
| 4 | 27.40 ± 0.89 h,i | 2.03 ± 0.07 k,l | |||||
| 75% Acetone | 1:5 | 0.074 | 13.48 | 70 | 1 | 27.31 ± 2.03 h,i | 2.03 ± 0.15 k,l |
| 2 | 29.83 ± 0.51 i | 2.21 ± 0.04 l | |||||
| 4 | 31.58 ± 1.59 i | 2.34 ± 0.12 l | |||||
| Water | 1:5 | 0.074 | 13.48 | 70 | 1 | 9.87 ± 0.08 f | 0.73 ± 0.01 h |
| 2 | 9.12 ± 2.19 f | 0.68 ± 0.16 h | |||||
| 4 | 8.83 ± 0.97 f | 0.66 ± 0.07 h | |||||