Sequential extraction of antioxidants from Citrus aurantium L. flower and kinetic evaluation of their effect on oil microparticle oxidative stability

This study applied supercritical CO₂ and ultrasound-assisted ethanol extraction (UAE) to obtain apolar and polar antioxidant fractions from <i>Citrus aurantium</i> flowers. HPLC-HRMS revealed distinct phytochemical profiles, with the polar extract showing higher phenolic content and antioxidant activity. Linseed oil was co-encapsulated with these extracts at varying concentrations (1, 2, and 5 mg/g of oil) using the Particles from Gas Saturated Solution (PGSS) technique, and the oxidative stability was assessed using isothermal calorimetry. Key kinetic parameters, such as induction time (τ), oxidation rates (<i>R</i> _<i>inh</i> <i>, R</i> _<i>uni</i> ), and antioxidant efficiency (<i>A.E</i>.), were measured. The polar extract demonstrated superior <i>A.E</i>., further confirmed by the DPPH stopped-flow assay. Co-encapsulation of both extracts produced an additive effect, surpassing the synthetic antioxidant BHT (200 μg/g). This study highlights <i>Citrus aurantium</i> flower extracts as natural antioxidants, enhancing the oxidative stability of encapsulated oils, while offering a sustainable method for bioactive compound recovery for food applications.