From Conventional to Sustainable Extraction: Improving Phenolic Species Recovery from Eucalyptus globulus Leaves

This research evaluates the influence of extraction method, solvent, and processing time on the recovery of phenolic compounds from Eucalyptus globulus leaves and their corresponding antioxidant capacity, through approaches with reduced energy and chemical consumption. Magnetic stirring (MS), and ultrasound- (US) and microwave-assisted (MW) extraction were applied using water or low-ethanol hydroalcoholic systems. Total phenolic content (TPC; Folin–Ciocalteu method) and antioxidant activity (AA; TEAC assay), were assessed to determine the functional properties of the extracts. FT-ICR MS was used to characterize the phytochemical profile. A hydroalcoholic system combined with non-conventional techniques improved extraction efficiency compared to an aqueous system and reduced the processing time. Among the investigated MW conditions, extraction at 360 W for 30 s provided the highest TPC and AA values (252 mg GAE/g DM; 65.67 mg TE/g DM), while US provided maximum TPC of 191 mg GAE/g DM (30 min extraction). MS showed the lowest performance (77 mg GAE/g DM). Phenolic acids, flavonoids, and ellagitannins were assigned across evaluated samples, indicating that the used conditions do not influence the extracts’ qualitative composition. Overall, MW extraction enabled rapid phenolic species recovery under short processing times and low-ethanol conditions, representing a promising approach among the investigated extraction systems.