Green extraction of phenolic compounds from plant matrices: A systematic review of yield, total phenolic content, and antioxidant activity (2019–2024)

Green extraction technologies are increasingly utilised to recover phenolic-rich bioactive compounds from plant matrices, aligning withsustainability and circular bioeconomy goals. This PRISMA-guided systematic literature review synthesises 69 peer-reviewed Q1/Q2 journal articles published between 2019 and 2024 that report extraction yield, total phenolic content (TPC), and antioxidant activity (AA) for green (UAE, MAE, PLE, SFE, SWE, and hybrid) and conventional methods applied to plant-based matrices. Across diverse leaves, peels, seeds, brans, and pulps, ultrasound-assisted extraction (UAE) and microwave assisted extraction (MAE) emerged as the most frequently applied and highest-performing techniques, typically delivering higher yields, TPC, and AA than Soxhlet or maceration when coupled with hydroalcoholic ethanol–water solvents. Matrix effects were evident: leaves and peels generally provided higher phenolic recovery than seeds, whereas cereal brans and seeds required pretreatments (e.g. alkaline hydrolysis, enzymatic treatment) or pressure-assisted methods to reach comparable performance. A strong positive relationship between TPC and AA (often R2 > 0.85) reinforced the role of phenolics as primary contributors to antioxidant capacity. Key process drivers across methods, which govern extraction yield, TPC, and AA, were solvent composition and polarity, solid–liquid ratio, temperature–time profiles, and the use of physical or chemical pretreatment. The review also shows that most studies remain at bench scale with limited reporting of energy use, solvent intensity, or CO₂-equivalent emissions, and almost no in vivo or clinical validation of bio‐efficacy. Accordingly, future research should couple optimised green extraction with standardised reporting, formal life cycle and techno-economic assessments, and in vivo studies to support the industrial translation of phenolic-rich plant extracts.