Separation of natural tocopherols from soybean oil byproduct with supercritical carbon dioxide

Oil deodorizer distillate (DOD), a byproduct from the soybean oil refining process, is rich in valuable compounds, such as natural tocopherols (vitamin E) and sterols. With the aim of concentrating tocopherols from methyl esterified DOD with supercritical CO2, a semi-continuous countercurrent process was developed using a fractionation column with a height of 2.4 m, an inner diameter of 20 mm, and a total volume of 750 mL. Operation parameters, pressure, the ratio of solvent to feed, and temperature of the column were investigated. The experimental results indicated that supercritical CO2 effectively extracts fatty acid methyl esters at 16 MPa with a column temperature gradient of 313–348 K. By increasing pressure, natural tocopherols (>50%) can be obtained with high recovery (>80%). It is concluded that supercritical CO2 fractionation is technically feasible for concentrating natural tocopherols from methyl esterified DOD.