Study on increasing the content of 6-gingerol from ginger rhizomes by supercritical fluid extraction and fractionation

The purpose of the study was to evaluate the optimum conditions applied by the supercritical fluid extraction and fractionation to maximize the content of 6-gingerol extracted from Ginger rhizomes. 3000Kg of Ginger rhizomes were collected from Jia Shian in Taiwan. The rhizomes were dried and ground into three granule-size groups, 0.297˜0.840mm, 0.840˜2.00 mm, and >2.00mm, respectively. The granules were extracted using supercritical carbon dioxide (SFE) under various combinations of pressures (80, 100, 120bar) and temperatures (35, 45, 55°C). The extracts collected under different conditions were then analyzed by HPLC to determine the content of 6-gingerol. The results showed that the extracts collected from 0.840˜2.00 mm group at 35°C and 200bar produced the greatest content of 6-gingerol, 20.23%. In order to evaluate the optimal conditions to further increase the content of 6-gingerol from ginger oil, 30Kg of SFE-obtained ginger oil by scaled-up SFE extraction was run by the supercritical fluid fractionation under different conditions. Selected pressures (80, 100, 120bar), temperatures (35, 45, 55°C), CO₂ flow rates/volumes of ginger oil (5/1, 10/1, 15/1) and re-extracted times (0, 1, 2) of collected ginger oil from separator were tested to evaluate the best conditions that can help increase the content of 6-gingerol from the fractionation extracts. The results showed that the greatest content of 6-gingerol, 68.83%, was collected under one specific set of conditions: 120bar, 35°C, 10/1 (CO₂ flow rate/volume of ginger oil) and re-extracted 2 times of collected ginger oil from the separator. The results may be utilized by the industry to enhance the 6-gingerol content during Ginger production.