Enhanced lycopene extraction from gac (Momordica cochinchinensis Spreng.) by the Z-isomerization induced with microwave irradiation pre-treatment

Abstract

This study aimed 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 reached 35.6% and 58.5% by microwave irradiation at 900 W for 40 sec and at 1050 W for 60 sec, respectively. The 35.6% and 58.5% Z-isomerization treatment improved 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 extraction, respectively) compared with no treatment. In addition, the extracts contained high amounts of lycopene Z-isomers, which have higher bioavailability and antioxidant capacity than (all-E)-lycopene.

Practical applications: This study clearly showed 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 indicated 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 increased 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.

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