Optimization of bioactive compounds extraction from <i>Red Cardinal</i> grape pomace using choline chloride and lactic acid-based deep eutectic solvent

Grape pomace, a major by-product of the wine and juice industries, presents considerable potential for extracting valuable bioactive compounds. This study aimed to optimize the extraction process using deep eutectic solvents composed of choline chloride and lactic acid. The extraction focused on three key factors: solvent-to-material ratio, extraction temperature, and extraction time, employing response surface methodology with a central composite design. The results showed that the optimal extraction conditions were achieved at a solvent-to-material ratio of 25:1 (v · w^-1), an extraction temperature of 70 °C, and an extraction time of 118 min. Under these conditions, the extract exhibited high levels of total phenolic content (81.90 ± 1.06 mg GAE · g^-1 DW), total saponin content (174.66 ± 2.87 mg AE · g^-1 DW), and total proanthocyanidin content (31.13 ± 0.50 mg CE · g^-1 DW). Furthermore, the extract demonstrated strong antioxidant capacity and antibacterial activities against four microbial strains (<i>Escherichia coli</i> ATCC 8739, <i>Salmonella typhimurium</i> ATCC 14028, <i>Bacillus subtilis</i> ATCC 6633, <i>Staphylococcus aureus</i> ATCC 6538). These findings underscore the extract's potential for diverse industrial applications, including the food, nutraceutical, and cosmetic sectors.