Antioxidant compounds and eugenol quantification of clove (Syzygium aromaticum) leaves extracts obtained by pressurized liquid extraction and supercritical fluid extraction

This study investigated the efficiency of supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE) to obtain clove leaf extracts. Further, the quality of the extracts in terms of yield, eugenol content, and antioxidant activity was evaluated. In both methods, the temperature had a positive effect on the yield of extract and eugenol. Ethanol extraction with pressurized liquid resulted in the highest extract yields of 3.70% (w/w) at 40 degrees C, 5.33% (w/w) at 50 degrees C, and 6.60% (w/w) at 60 degrees C. The highest total yield resulted from eugenol with 2.66 g per kg of leaves, i.e., 0.266% (w/w). However, the SFE extract yield was 1.94% at 300 bar and 60 degrees C with a high eugenol yield of 8.06 g per kg of leaves, i.e., 0.806% (w/w). SFE-CO2 demonstrated efficiency for eugenol-rich extracts. PLE and SFE-CO2 showed satisfactory results for antioxidant capacity and content of phenolic compounds.