Effects of high water content and drying pre-treatment on supercritical CO2 extraction from Dunaliella salina microalgae: Experiments and modelling

Abstract

This study investigates the effects due to the water content and to the drying pre-treatment on the extraction kinetics of solutes extracted from Dunaliella salina microalgae by supercritical CO2. The extraction experiments were conducted at pressure range from 20 up to 40MPa at a temperature of 333K on crushed samples with water content varying from 5.5 up to 23wt%. Three drying pre-treatments were applied: air flow drying at 318K, air flow drying followed by additional microwave treatment and freeze-drying. A water content up to 23wt% helps to extract a higher content of carotenoids (mainly β-carotene) and does not restrict the extraction process. Sovová’s mathematical model was applied and the parameters were adapted for the description of the extraction curves from samples containing high water content with a deviation between experimental and calculated values comprised between 1.1% and 4.3%.