Comparison of conventional and ultrasound assisted supercritical carbon dioxide extraction of curcumin from turmeric (Curcuma longa L.)

Recently, ultrasound assisted supercritical fluid is used for extraction the valuable compounds from a number of plant materials as an alternative to conventional method because it can enhance the extraction rate and yield. Curcumin is an important component of turmeric (Curcuma longa L.) with many useful functions to human health. The objective of this study is using ultrasonic assisted supercritical carbon dioxide (USC-CO₂) to extract curcumin from turmeric and compared to conventional method. The effect of operating conditions on extraction, including temperature (40-60 °C), pressure (15-25 MPa), extraction time (30-120 min), CO₂ flow rate (2-4 mL/min) and percentage of cosolvent (10-20% v/v) were also studied. The result shows that the high extraction yield of 7.17% w/w and curcumin content of 1.69% w/w were achieved at temperature of 50 °C, pressure of 25 MPa, extraction time of 90 min, CO₂ flow rate of 3 mL/min with 10% cosolvent. Compared to conventional method, USC-CO₂ could provide higher curcumin content in extraction yield in a shorter extraction time. Scanning electron microscopy (SEM), thermal gravity (TG), and fourier transform infrared spectroscopy (FTIR) was used to analyse turmeric undergoing USC-CO₂ and conventional extraction and showed that ultrasound could break down the cell walls and remove some functional groups from plant materials, resulting an increase the selectivity of compounds in extraction yield.