Table 2.
Comparison of novel green extraction methods used for the extraction of flavonoids from grape seeds.
| Method | Grape Variety/Sample Type | Processing Conditions | Total Flavanoids Content | Major Compounds Determined | Reference |
|---|---|---|---|---|---|
| MAE | Vitis vinifera L., “Napoleon” variety, skin and seeds | 100 °C; solvents: methanol, ethanol, acetone, and water; 100–500 W; ratio sample to solvent 10–50 mg mL−1; 5–20 min; magnetic stirring: 0–100% |
75.9 mg/100 g + 2.2 mg (caffeic acid equivalent)/100 g + 6.1 mg (rutin equivalent)/100 g | phenolic acids: caftaric acid flavanols: catechin, epicatechin flavanol glycosides: dihydrokaempferol-glycoside, quercetin, quercetin-3-O-glucoside, kaempferol-3-O-glucoside |
[64] |
| UAE | Vitis vinifera L., Syrah variety, grape skin residue | 80% ethanol; 55 ± 5 KHz ultrasound; 190 rpm; 25 °C–60 °C; 10–30 min |
9.8–40.0 mg quercetin equivalent/100 g |
phenolic acids: gallic acid, caffeic acid, caftaric acid flavanols: catechin, procyanidin B1, procyanidin B2 flavanol glycosides: kaempferol-3-O-glucoside, quercetin-β-D-glucoside, isorhamnetin-3-O-glucoside-chloride, myricetin, rutin anthocyanins: malvidin-3-O-glucoside-chloride, cyanidin-3-O-glucoside-chloride, pelargonidin-3-glucoside-chloride, delfinidine-3-O-glucoside, peonidine-3-O-glucoside stilbenes: cis-reservatril, trans-reservatrol, viniferin |
[65] |
| ASE | Vitis vinifera L., cv. Cabernet Sauvignon, wet and dry grape pomace | 45 °C–140 °C; solvent: 70% ethanol/water |
∼1000 mg GAE/100 g at 140 °C for wet pomace and 600 mg GAE/100 g at 80 °C for dry pomace | phenolic acids: gallic acid, protocatechuic acid flavanols: gallocatechin, catechin, prodelphinidin B3, epicatechin |
[66] |
| EAE | Vitis vinifera, cv. Regen, grape skin | 45 °C; 3 h; pH 2.0, enzyme types: EX-V*, HC*, ER*, ECP*, enzyme dosage of 10.52 mg/g | 4581.7 mg/100 g (with EX-V*) 4467.7 mg/100 g (with HC*)4358.8 mg/100 g (with ER*)4316.9 mg/100 g (with ECP*) |
flavanols: galocatechin, procyanidin B1, epigallocatechin, catechin, procyanidin B2, epicatechin flavanol glycosides: myricetin-3-O-glucoside, rutin, quercetin-3-O-glucuronide, quercetin-3-O-glucoside, kaempferol-3-O-glucuronide, isorhamnetin-3-O-glucoside anthocyanins: delphinidin-3,5-O-diglucoside, cyanidin-3,5-O-diglucoside, delphinidin-3-O-glucoside, peonidin-3,5-O-diglucoside, malvidin-3,5-O-diglucoside, cyanidin-3-O-glucoside, peonidin-3-O-glucoside, malvidin-3-O-glucoside | [67] |
| SLE | 70% aqueous ethanol containing 1% formic acid for one day in the dark; 40 °C | 4462.2 mg/100 g |
MAE, microwave assisted extraction; UAE, ultrasound assisted extraction; ASE, accelerated solvent extraction; SLE, solid-liquid extraction; EAE, enzyme assisted extraction; GAE, Gallic acid equivalent; EX-V*, enzyme type: Lallzyme EX-V; HC*-enzyme type: Lallzyme HC; ER*-enzyme type: Endozym rouge; ECP*-enzyme type: Endozym contact pelliculaire; * as given in [68].