Experimental and modeling study of polyphenols in Olea europaea leaves through ultrasound-assisted extraction

Abstract

Olive tree (Olea europaea) leaves were extracted by ultrasound-assistedextraction (UAE). The attention was focused on the yield of extract and its polyphenols,and extraction kinetics to contribute to the application of the extraction processindustrially. Samples were extracted with water, ethanol, methanol, and their aqueoussolutions (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 thesolvent. Backing the solvents with water enhanced the polyphenolic yield. Total phenoliccontent (TPC) from water extracts decreased after a certain temperature point, as a resultof the problems of degradation. The second-order model was followed for characterizingthe kinetic of the UAE process of TPC from olive leaves under various solvents andtemperatures. Major phenolic component was also quantified for each solvent system bymeans of High Performance Liquid Chromatography (HPLC).