Combination of expeller and supercritical CO2 for the extraction of a phenolic-rich olive oil – A preliminary chemical characterization

This study aimed to develop and evaluate a sustainable olive oil (OO) extraction process that eliminates wastewater generation while producing high-quality oil and preserving the food-grade potential of byproducts. The method involves olive dehydration followed by a sequential two-step process combining cold pressing and supercritical CO 2 extraction (SFE-CO 2 ). This approach achieved a significantly higher extraction yield (92.6 %) compared to the 2-phase conventional process (37.8 %) while eliminating aqueous residues and avoiding the use of organic solvents or refining steps. A chemical analysis confirmed the extracted OO’s superior quality, with parameters like acid value, peroxide value, absorption coefficients (K 232 , K 270 , ΔK), and fatty acid profile, meeting legal limits for extra virgin classification. Notably, the absence of water during extraction and the use of SFE-CO 2 significantly enhance the concentration of phenolic compounds (PCs) in the oil, press cake, and defatted flour. Preliminary analysis revealed PCs such as tyrosol (29 mg/kg), hydroxytyrosol (13 mg/kg), syringic acid (9.6 mg/kg), pinoresinol (1.8 mg/kg), and oleuropein (0.4 mg/kg), representing 3.7–16 times higher levels than those typically found in conventional OO. This method provides a sustainable and efficient alternative for OO extraction, enhancing the oil and byproducts’ nutritional value.