Oil extraction from coriander fruits by extrusion and comparison with solvent extraction processes

Abstract

The aim of this work was to optimise a single-screw extruder dedicated to coriander production and to investigate the effects of screw configuration, nozzle diameter and nozzle/screw distance. On the other hand, the coriander fruit was extracted using soxhlet methods, the results were compared with mechanical screw press methods. Maximum yield was obtained with single screw extruder for a configuration allowing the strongest oil expression (nozzle/screw distance: 3 mm, nozzle diameter: 9 mm). Comparing with mechanical press, the maximum yield was obtained by the soxhlet extraction with 21.25%. The effect of the operating parameters on oil quality was not important. In all the experiments tested, the oil quality was very good. The acid value was below 1.8 mg of KOH/g of oil and iodine values were tolerable (44 mg of iodine/100 g of oil). Nine fatty acids were identified, with petroselinic acid accounting for 74–77% of the total fatty acids, followed by linoleic, oleic and palmitic acids, accounting for 12–13%, 4–6% and 3%, respectively, of the total fatty acids. β-Sitosterol was the major sterol in all oils with 28% of total sterols of all oils. The next major sterols in all oils were stigmasterol (24–27% of total sterols) and Δ 7-stigmasterol (14–18% of total sterols).