Abstract:

Olive tree (Olea europaea) leaves were extracted by ultrasound-assisted extraction (UAE). The attention was focused on the yield of extract and its polyphenols, and extraction kinetics to contribute to the application of the extraction process industrially. Samples were extracted with water, ethanol, methanol, and their aqueous solutions (50%, v/v) under temperature values ranging from 30 to 50 °C. Additionally, the temperature interval changed between 30 and 80 °C, when water was used as solvent. Backing the solvents with water enhanced the polyphenolic yield. Total phenolic content (TPC) from water extracts decreased after a certain temperature point, as a result of degradation problems. The second-order model was followed for characterizing the kinetic of the UAE process of TPC from olive leaves under various solvents and temperatures. Major phenolic component was also quantified for each solvent system  by means of High Performance Liquid Chromatography (HPLC).

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