Supercritical CO2 extraction of Walnut (Juglans regia L.) oil: extraction kinetics and solubility determination

Experimental and modelling investigations of supercritical CO2 extraction of oil from Juglans regia L. kernels were conducted at 200 and 400 bar, 313 and 333 K at a CO2 flow rate of 0.1 kg/h. Regardless of the pressure and the temperature, the highest achievable yield was estimated at about 0.7 kgoil / kgbiomass. The extraction kinetics were modeled with Sovová's broken and intact cells model. Walnut oil apparent solubility in supercritical CO2 was determined and modelled with the Chrastil equation. A retrograde solubility behaviour was observed at 200 bar, the faster extraction kinetics were found at 400 bar and 333 K. The fatty acid composition of the supercritical CO2 extracted oil was compared to the quality of the oil extracted by press and n-hexane Soxhlet extraction.