ABSTRACT
<p><b>OBJECTIVE</b>To look for optimum extraction techniques for oleuropein by boiling olive leaves at low temperature and reduced pressure.</p><p><b>METHOD</b>According to single factor experiment (SFE) design, the effects of seven factors, the impact of seven factors, type of solvent, temperature, time, ratio of material to liquid, ethanol concentration, vacuum degree and extraction times, on extraction yield of oleuropein were investigated. Based on the results of SFE, four more important factors, temperature, time, ratio of material to liquid and ethanol concentration, were selected in L9 (3(4)) orthogonal experiment (OE) to compare with those extracted with traditional methods.</p><p><b>RESULT</b>The optimum conditions for boiling extraction of oleuropein at low temperature and reduced pressure were as follows: temperature 60 degrees C, time 20 min, ratio of material to liquid 1:30 and ethanol concentration 85%. The conditions presented an extraction yield of 5.90%.</p><p><b>CONCLUSION</b>Compared with traditional extraction methods and the ultrasound assisted extraction method, boiling extraction techniques at low temperature and reduced pressure were so quick and efficient that it has a good application prospect.</p>