Comparison of Different Extraction Methods of Akebia trifoliata Oil and Optimization of Supercritical CO₂ Extraction Process

Taking Akebia trifoliata (Thunb.) koidz seeds as raw materials, the extraction technology of seed oil by soxhlet extraction method, ultrasonic-assisted extraction method, aqueous enzyme method, three-phase partitioning distribution method and supercritical CO₂ extraction method were studied. The results showed that the yield of aqueous enzyme method was the lowest (11.00%), and the seed oil was seriously emulsified. The seed oil extracted by three-phase partitioning distribution method and ultrasonic-assisted extraction method had peculiar smell and poor quality, the yield of seed oil was higher than that of aqueous enzyme method, which was 17.42% and 29.40%. Respectively, the yield of soxhlet extraction method could reach 32.32%, but need a long time. In contrast, supercritical CO₂ extraction had the advantages of short extraction time, high yield, simple operation and no organic solvent introduced. The optimum extraction conditions were determined via response surface analysis just as follows: Extraction time, extraction kettle pressure and extraction kettle temperature were 100 min, 28 MPa and 34 ℃. The yield of seed oil was 37.01%. The experiment was repeated for three times under the optimal conditions, and the final yield was 36.87%±0.08%.