Extraction of Antioxidants in Sweetpotato Waste Powder with Supercritical Carbon Dioxide

The application of supercritical carbon dioxide (SC-CO2) extraction to waste powder derived from sweetpotato roots with orange flesh in a food processing factory was examined. The contents of antioxidants, β-carotene, α-tocopherol and chlorogenic acid, remaining in the waste powder after SC-CO2 extraction under different conditions were determined by HPLC. At a constant extraction pressure, the extraction yield of β-carotene from the waste powder was highest at 40°C, decreased at 60°C and decreased further at 80°C; in contrast, the α-tocopherol yield did not vary under different temperature conditions. At a constant extraction temperature, increasing extraction pressure in-creased the extraction yields of both β-carotene and α-tocopherol. Under the conditions tested, the yields of β-carotene (95.1%) and α-tocopherol (76.8%) were highest at 40°C and 35 MPa. Little chlorogenic acid was extracted from waste powder. The β-carotene remaining in the waste powder after SC-CO2 extraction correlated well with its color value of a*.