Effects of CO₂ Flow Rate in Supercritical Fluids Extraction of <em>Polygonum minus</em> Roots

Abstract

>Polygonum minus (locally known as Kesum) roots has been reported to contain bioactive sesquirtepenes compound, which is β-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 β-caryophyllene yields from P.minus roots. The extraction pressure, temperature and time were fixed at 80 bar, 40^oC 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 β-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 β-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 β-caryophyllene from P.minus roots.