Process optimization of ultrasound-assisted extraction coupled with resin adsorption for recovery and purification of phenolic antioxidants from Ulex europaeus

Ulex europaeus , a widely distributed invasive species, represents a promising source of phenolic compounds with potential for industrial valorisation. Given its underexploited chemical richness, advancing efficient and sustainable routes for its fractionation is essential, and this study represents one key stage within a pathway toward gorse-based biorefinery schemes. This study proposes a sustainable strategy based on ultrasound-assisted extraction using an ethanol/water mixture 50 % (v/v), combined with a purification step using non-ionic polymeric resins (SEPABEADS SP700). Extraction conditions (amplitude, temperature and time) were optimized through a Box–Behnken design, achieving an extraction yield of 26.27 % and a phenolic content of 9.68 g GAE/100 g extract under optimal conditions (90 %, 41 °C, 70 min, respectively). Resin treatment increased the phenolic content to 18.84 g GAE/100 g extract, improving extract purity. Antioxidant capacity was evaluated using ABTS, FRAP, and DPPH assays. Phenolic compounds were identified by HPLC–MS/MS, revealing 23 polyphenols, with genistein (89.80 mg/100 g) and vitexin (82.58 mg/100 g) as the most abundant. Overall, the results highlight the critical role of chemical engineering in designing sustainable and efficient processes for biomass valorisation.