Effect of extraction methods on characteristic and composition of Indonesian cashew nut shell liquid

Long chain phenols contained in cashew nut shell liquid (CNSL) are found to have important pharmaceutical applications, such as antitumor, antimicrobial, urease inhibitory and lipoxygenase activities, and also are well known in coating and resin industry. The impact of different extraction methods on CNSL yield, selectivity towards preferable compounds, composition and characteristic of extracts was investigated. Four different methods employed in extracting CNSL from CNS were: supercritical carbon dioxide (SC-CO2) extraction (40 °C, 300 bar, 4 h), subcritical water (SCW) extraction (140 °C, 22 bar, 1 h), soxhlet extraction (solvent boiling point, atmospheric pressure, 30 h), and two-step extraction, which comprises a solvent extraction followed by a SCW extraction. Characteristic of the extracts differed significantly. Methanol and two-step extraction resulted in darker and more turbid extracts, while n-hexane and SC-CO2 extracts were clearer and lighter in color. GC-FID/MS chromatograms showed differences in compositions of the extracts obtained by different methods. Two-step extraction yielded extracts that contain 81.17–82.98% total long chain phenols (around 50% based on dry CNS) with monounsaturated cardanol as the major compound, producing higher amount of total phenols than other methods. SCW extraction showed high selectivity towards monounsaturated cardanol and stigmasterol, while high concentration of monounsaturated anacardic acid and cardol appeared in SC-CO2 extract.

► Cashew nut production waste contains high concentration of long chain phenols.
► Four different extraction techniques with different conditions were employed.
► Extract, obtained by two-step extraction, contains 81.17–82.98% long chain phenols.
► Cardanol and stigmasterol were highly extracted by subcritical water extraction.
► Supercritical CO2 showed high selectivity towards anacardic acid and cardol.