Enhanced Lycopene Extraction from Gac (Momordica cochinchinensis Spreng.) by the Z-Isomerization Induced with Microwave Irradiation Pre-Treatment

This study aims to improve the efficiency of lycopene extraction from gac (Momordica cochinchinensis Spreng.) by the Z-isomerization induced with microwave irradiation pre-treatment. Although 93.6% of lycopene exist as all-E-isomers in dried gac aril, the total Z-isomer content reaches 35.6 and 58.5% by microwave irradiation at 900W for 40s and at 1050W for 60s, respectively. The 35.6 and 58.5% Z-isomerization treatment improves lycopene content of extract (by 6.0 or 8.5 times for press extraction, 7.8 or 13.5 times for ethanol extraction, and 4.5 or 6.1 times for supercritical CO2 (SC-CO2)extraction, respectively) compared with no treatment. In addition, the extracts containes high amounts of lycopene Z-isomers, which have higher bioavailability and antioxidant capacity than (all-E)-lycopene.Practical Applications: This study clearly shows that lycopene recovery by press, organic solvent, and SC-CO2 extraction from dried gac aril improved by the increase in the Z-isomer content. It indicates that the Z-isomers are more soluble in oil, organic solvent, and SC-CO2 than the all-E-isomer. Moreover, the thermal Z-isomerization pre-treatment increases the content of lycopene Z-isomers in the extract. Therefore, this procedure is important not only for improving the productivity of lycopene, but also for providing a highly functionalized extract. The effect of the Z-isomerization, induced by microwave irradiation pre-treatment of gac (Momordica cochinchinensis Spreng.) aril, on the lycopene recovery and lycopene content of the extracts obtained using press, ethanol, and SC-CO2 extractions is investigated. For all extraction methods, as the content of Z-isomers in the raw material increases, the recovery and lycopene content of gac extracts improve.