Valorization of agrifood waste: Optimizing bioactive extraction using accelerated solvent extraction with three solvent systems

The increasing demand for bioactive compounds from natural sources is focusing attention on agrifood by-products for applications beyond composting. A waste-to-value strategy, paired with energy-efficient extraction methods such as accelerated solvent extraction (ASE), represents an environmentally friendly approach contributing to sustainable development. The objectives of this research are aligned with these guidelines, studying by-products from the industrial processing of quince, broccoli, grapes, pea, prickly pear, and almond. The ASE process was optimized by varying the extraction solvent (ethanol, acetone and methanol) and the amount of sample used (0.5,1 and 1.5 g) in each extraction cycle (1, 2 and 3). Solvent type proved to have a significant impact on extraction yield, phenolic content, and both antioxidant and antifungal activity. Methanol was the most efficient solvent overall, and the highest yields were obtained from prickly pear peel (43.3 %) and broccoli discards (26.4 %). Epicatechin (16.8-38.6 mg/g extract), ellagic acid (3.5-6.4 mg/g extract), and catechin (2.6-3.4 mg/g extract) were the most abundant compounds identified. By-products from quince (QB) and grapes (stem and skin) exhibited the highest antioxidant activity (QB: 7.0; stem: 6.7; skin: 6.3 mmol TEAC/100 g extract) and total phenolic content (skin: 81.7; stem: 67.0 and QB: 31.6 mg GAE/g extract). Extracts were active against five mold strains, with some demonstrating superior activity against Aspergillus puulaauensis and A. jensenii over the standard, natamycin. Finally, extracts that combined the best antifungal and antioxidant properties were quantitatively ranked. Collectively, this research establishes a foundation for designing green preservatives and advances the circular economy via efficient resource valorization.