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 Citrus aurantium 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 (R inh , R uni ), and antioxidant efficiency (A.E.), were measured. The polar extract demonstrated superior A.E., 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 Citrus aurantium flower extracts as natural antioxidants, enhancing the oxidative stability of encapsulated oils, while offering a sustainable method for bioactive compound recovery for food applications.