The impact of supercritical CO₂ conditions on extracting antioxidant compounds from tangerine leaves (Citrus reticulata) for enhancing oxidative stability in soybean oil

Tangerine leaves were valorized as a source of natural antioxidants for protecting soybean oil against lipid oxidation. Initial Soxhlet extracts obtained using hexane (Hex S), ethyl acetate (EtOAc-S), and ethanol (EtOH-S) showed that the Hex-S extract provided the highest oxidative stability, highlighting the relevance of nonpolar compounds in delaying lipid oxidation. To develop a more sustainable alternative to hexane extraction, supercritical CO 2 (SC-CO 2 ) extraction was optimized using a central composite design, assessing the effects of pressure (100, 200, and 300 bar) and temperature (40, 50, and 60 °C) on the extract's antioxidant performance. The optimal SC-CO 2 extract, obtained at 273 bar and 37 °C, extended the induction period of soybean oil oxidation to 5.2 h, outperforming both the Hex-S extract (4.4 h) and the control sample (3.8 h), and resulted in a lower p-anisidine value (13.36). These activities may be attributed to extracted bioactive compounds, such as linalool, thymol, and tangeretin. • Tangerine leaves arrayana variety were valorized as a natural antioxidant source. • Optimal SC-CO₂ extraction conditions (37 °C, 273 bar) enhanced the extract composition. • Monoterpenes, sesquiterpenes, and flavonoids were selectively recovered. • The extracts improved soybean oil oxidative stability (induction time increased). • Extraction time decreased from 10 h to 40 min with minimal solvent residue.