Effect of supercritical carbon dioxide flow rate on extraction yield, antioxidant properties and morphological changes of Quercus infectoria galls

The extraction condition of supercritical carbon dioxide (SC-CO2) extraction was used to extract Quercus infectoria galls, a medicinal plant which rich with bioactive compound, in order to maintain the green environment as well as the quality of the product. The study was performed to investigate the effect of extraction parameter (CO2 flow rate) on Quercus infectoria galls extract using SC-CO2 extraction. Then, the extract was analysed to determine their antioxidant activity and morphological changes of the Quercus infectoria galls before and after the extraction. Hence, three different CO2 flow rate have been investigated which were 2, 3, and 4 mL/min while pressure (P) and temperature (T) were fixed at highest density (P: 30 MPa, T: 40oC). The results obtained from this study showed the solvent flow rate of 2 mL/min give the highest percentage of extraction yield which is 0.37% compared to others. The extracts were screened for possible antioxidant activity by antioxidant activity 2,2-diphenyl-1-picryl hydrazyl (DPPH) assays. In this study, the best result obtained was at flow rate of 3 mL/min with inhibition percentage of 96.97% but it showed insignificant difference with other CO2 flow rates. The change in morphology of the galls was significant when observed using scanning electron microscope (SEM). These results indicated that SC-CO2 extraction could be an alternative method for extraction of antioxidative compound from Q.infectoria gall