Separation of cashew (Anacardium occidentale L.) nut shell liquid with supercritical carbon dioxide

Cashew nut shell liquid (CNSL) represents the largest readily available bioresource of alkenyl phenolic compounds. In this work, separation of CNSL from the pericarp of the cashew nut with supercritical carbon dioxide was studied. In the initial extractions with CO₂ at 40-60°C and at pressures from 14.7 to 29.4 MPa, low yields were obtained. However, when the extractions were performed with one or more intermediate depressurization steps, the yield of CNSL increased to as high as 94%. Most of the oil did not separate from the shell during the depressurization step, but was obtained during the subsequent repressurization. The CNSL extract had a clear light brownish pink color and exhibited no evidence of polymerization or degradation. The pressure profile extraction method proposed in this work increases the possible CNSL extraction yields and greatly reduces the amount of CO₂ required for CNSL separation.