Extraction of pomegranate seed oil using subcritical propane and supercritical carbon dioxide

Extraction of oil from pomegranate seeds as a waste product of the juice industry using supercritical carbon dioxide and subcritical propane was studied in this work. The influence of the main operating conditions of extraction, namely, the temperature and pressure of extraction on the oil extraction yield and the correspondent fatty acid profile were analyzed and reported here. Soxhlet extraction with n-hexane was done for comparison with supercritical extraction resulting in a maximum yield of oil of 22.31 wt %. Supercritical carbon dioxide and subcritical propane extracted up to 58.53% (corresponding to maximum yield of 13.06 wt %) and 76.73% (corresponding to maximum yield of 17.12 wt %) of the total amount of pomegranate seed oil as measured using Soxhlet extraction, respectively. Results indicated that the subcritical propane is a suitable and selective solvent for the extraction of the pomegranate seed oil in function of smaller times and pressures employed compared to carbon dioxide extraction. The fatty acid composition of the extracted oil showed the presence of fatty acids of C-16, C-18, C-20, C-22, and C-24 carbon chains. Punicic (C-18.3) was the major fatty acids and comprise up to 70% of the total fatty acid content of the extracted oil among all samples. Finally, Lack's plug flow model as developed by Sovova was applied to both extraction systems and a good agreement with the experimental results was obtained.