Comparative characterization of herb-supplemented cold-pressed sunflower oil: Stability, shelf life, and environmental sustainability

Abstract This study comparatively investigated the oxidative stability, shelf-life, and environmental sustainability of cold-pressed sunflower oil supplemented with natural herbs through a natural maceration approach (1% w/v). The physicochemical properties, oxidative stability indicators (free fatty acids, peroxide value (PV), thiobarbituric acid reactive substances (TBARS)), antioxidant capacity (TPC, DPPH, FRAP), fatty acid composition were assessed after 21 days and 8 months. The Rancimat accelerated storage test, thermal oxidation behavior (DSC), and life cycle assessment (LCA) were also evaluated after 8 months, rosemary- and sage-supplemented oils exhibited the lowest PV values (34.6–37.0 meq O₂/kg) and TBARS levels (4.2–4.6 μg MDA/mL), corresponding to a 45–55% reduction relative to the crude control oil. In contrast, lavender showed pronounced pro-oxidant behavior, reaching a PV of 68 meq O₂/kg and TBARS of 10.6 μg/mL. Rosemary demonstrated the highest antioxidant activity (DPPH: 0.344 mg TE/mL), representing a 50–60% increase over the control, and extended the induction time from 2.05 h to 4.05 h. Polyunsaturated fatty acids were effectively preserved in rosemary- and sage-treated oils, with levels maintained at 62–63% compared to 54% in the control. DSC analysis revealed up to a 30% reduction in oxidation enthalpy (ΔH) in antioxidant-rich oils, confirming enhanced thermal-oxidative stability. LCA results revealed that natural maceration reduced global warming potential by approximately fourfold (2.69E-3 vs. 1.06E-2 kg CO₂ eq/kg oil) compared to conventional refining. Overall, rosemary and sage emerged as the most effective clean-label natural alternatives to synthetic antioxidants significantly extending shelf life, preserving nutritional quality, and reducing environmental impacts. Graphical Abstract