Technological Study on Extraction of Volatile Oil from Onion by Supercritical CO_2

In this study the supercritical CO2 extracting technology was applied to extract volatile oil from freeze-dried onion powders.Single factor experiment and orthogonal design were used to study the influences of extracting conditions on the yield of volatile oil.The optimum extracting parameters were established with extracting pressure of 20 MPa,extracting temperature of 35 ℃,flow rate of CO2 of 14 kg/h and the extracting time of 2.5 h.The optimum technology for supercritical CO2 extraction of volatile oil from freeze-dried onion powders was high efficient,and the yield of volatile oil was up to 0.53 %.