High-throughput extraction method for phenolic compounds in olive fruit (Olea europaea)

Phenolic compounds in olive fruit significantly influence the health benefits and sensory properties of processed olive oil and table olives. A simple and rapid extraction method using homogenization with dimethyl sulfoxide (DMSO) and solid-phase extraction (SPE) cleanup was developed and optimized for ten phenolics in olive fruit. Quantification was performed using high-performance liquid chromatography with diode-array detection (HPLC-DAD). Chromatographic separation of the relevant compounds was achieved using a C18 column (5 μm, 4.6 × 250 mm). The method was validated for accuracy and precision using replicate fortifications (n = 5) in 3 olive matrices (fresh, brined and California-style olives). All compounds were recovered between 80 and 120% and had relative standard deviations below 12.5%. Limits of detection (LOD) and limits of quantification (LOQ) ranged from 0.06 to 7.4 mg/kg and 0.20 to 23.3 mg/kg, respectively. The method was used to quantify phenolic concentrations in fresh olives at different maturities, brined olives and California-style olives, including the analysis of green ripe olives and black ripe olives processed without ferrous gluconate for the first time.