Valorization of Isabella Grape (Vitis labrusca L.) Pomace Through the Recovery of Nutraceuticals by Sequential Green Extraction Technologies

Isabella grape pomace (IGP) the primary by-product of Colombia's winemaking industry, represents a promising source of nutraceuticals with potential uses in the food industry. This study developed a sequential green extraction process to recover nutraceutical from IGP. The approach integrated supercritical fluid extraction with CO₂ (SFE-CO₂) to obtain lipophilic compounds, followed by SFE with ethanol/water as co-solvent (SFE-CO₂/EtOH:H₂O) for medium-polarity phenolics, and pressurized liquid extraction (PLE) with EtOH:H₂O to recover the polar phenolic-rich fraction. The extraction parameters were optimized using response surface methodology, and optimal conditions were identified: SFE-CO₂ at 31.7 MPa/58.9 °C yielded 6.95% extract rich in linoleic acid (65.5%) and α-tocopherol (107.2 mg/kg); SFE-CO₂/EtOH:H₂O with 15% of co-solvent produced extracts with high phenolic content (105.35 mg GAE/g) and antioxidant activity (0.18 mmol TE/g); while PLE at 58.91% of EtOH/107.98 °C achieved notable recovery of flavonoids (757.18 mg QE/g), anthocyanins(1508 μg MAE/g) and condensed tannins (258.39 mg ECE/g), with potent antioxidant capacity (130.40 mmol TE/g). The sequential process demonstrated synergistic effects, with a total cumulative yield of 41.08% and phenolic recovery of 349.89 mg GAE/g extract. This approach offers a sustainable biorefinery approach for transforming IGP into high-value nutraceutical ingredients.