Analysis of the operation conditions for supercritical fluid extraction of seed oil

In this paper, a SCFE set-up with an extraction volume of 1 L was established, with which Hippophae rhamnoides L. seed oil was extracted using supercritical CO2. The experiments show that many factors have impacts on the oil yield, such as extraction pressure, temperature, and fluid flow rate, as well as seed particle size and filling quantity. For the extraction process of Hippophae rhamnoides L. seed oil, the optimum conditions were as follows: extraction pressure of 20-30 MPa, extraction temperature of 35-40 °C, supercritical CO2 flow rate of 0.15-0.3 m3/h, and extraction time of 4-5 h. Under such a condition, the oil obtained is very lucid and good quality, and the yield is as high as above 90%. GC analysis shows that the oil contains 11.44% of saturated fatty acid and 88.56% of unsaturated fatty acid. From the changes of oil yield with the extraction time, it can be concluded that the extraction process contains three stages: fast extraction stage (approximate a linear style), transitional stage (very short period of time) and the slow extraction stage (just a little amount of oil can be extracted in this stage). At the first stage, 75-80% of the oil has been extracted out.