Abstract:

The production process of cold pressed evening primrose oil and the supercritical CO2 extraction process of oil
from the cake left were optimized by orthogonal array design. The optimal process conditions for producing cold pressed
evening primrose oil were 75 ℃, 6% of water content, 3.0 MPa and 36 r/min. The cold pressed oil obtained under these
conditions contained 9.5% γ-linolenic acid and the remaining residue showed a residual oil content of 8.6%. The optimal
process parameters for supercritical CO2 extraction of oil from this residue were found to be 50 mesh of particle size, 4% of
water content, 3 h, 35 MPa and 35 ℃, resulting in an oil yield of 94.9%.

Key words: evening primrose oil；cold press；supercritical CO2；&gamma, -linolenic acid