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Ultrasound-assisted solid liquid extraction (USLE) of olive fruit (Olea europaea) phenolic compounds

Jerman, T., Trebše, P., Mozetič Vodopivec, B.
Food chemistry 2010 v.123 no.1 pp. 175-182
ultrasonic treatment, extraction, olives, Olea europaea, phenolic compounds, food analysis, food composition, food processing quality, new methods
A new method of ultrasound-assisted solid liquid extraction (USLE) of olive fruit phenols is described. Phenolics were extracted using high intensity probe ultrasonication and analysed by HPLC-DAD-FLD-MS/MS. Four USLE parameters - sonication time (4, 15, 20, 30min), temperature (25, 45°C), solvent composition (80%, 100% methanol) and extraction steps (1-5) were studied and optimised on the basis of nine major olive fruit phenols. A three-step extraction of 20min with pure methanol (25mL) at 45°C was needed for sufficient phenol recoveries (94.1-98.7%) from 1.5g of freeze-dried olive fruits. The proposed USLE method was more efficient in comparison to US bath and agitation, with up to 33% and 80% enhancement in the case of oleuropein, respectively. In addition, the overall method provided high selectivity, precision and sensitivity with LODs/LOQs ranging from 0.66-4.92μgg⁻¹ and 2.00-14.77μgg⁻¹ of olives DW, respectively.