Effects of CO2 Flow Rate in Supercritical Fluids Extraction of Polygonum minus Roots

Polygonum minus (locally known as Kesum) roots has been reported to contain bioactive sesquirtepenes compound, which is ss-caryophyllene. In this study, supercritical fluid extraction using carbon dioxide was employed to investigate the effects of CO2 flow rate (2 ml/min, 3ml/min and 4 ml/min) towards essential oil yield (EO) and ss-caryophyllene yields from P.minus roots. The extraction pressure, temperature and time were fixed at 80 bar, 40(o)C and 240 min, respectively. The results showed the highest amount EO obtained at flow rate 4 ml/min with 33.3% followed by flow rate 3 ml/min and 2 ml/min were 24% and 12.4% respectively. On the other hand, the highest amount ss-caryophyllene was obtained at the lowest flow rate of 2 ml/min with 7.69% yield, followed by 3ml/min (1.62%) and 4 ml/min (1.54%). It can be explained that by increasing the CO2 flow rate, it will increase the initial extraction rate and the overall extraction of EO. However, mass transfer resistance limits the amount of ss-caryophyllene transported to the bulk solvents with increasing CO2 flow rate. Thus, further study is needed to overcome the mass transfer limitation and improve the overall extraction of ss-caryophyllene from P.minus roots.