From Fig. 3a, extraction from the wet paste obtained a higher
final lipid yield than from dried biomass (lipid yieldwet = 0.071 g
lipid extract/g dried microalgae, while lipid yielddry = 0.058 g lipid
extract/g dried microalgae). Despite the common view that residual
water in the cells acts as a barrier which impedes mass transfer
of the analyte molecules into the bulk fluid, a few studies on SCCO2
extraction of miscellaneous analytes from moist samples (caffeine
from green coffee beans and essential oil from Origanum vulgare
leaves) have demonstrated that residual water in the feedstock
does not reduce extraction performance. Water was found to aid
extraction through its swelling of the cellular matrix and its natural
role as a polar co-solvent (Pourmortazavi and Hajimirsadeghi,
2007; Schwartzberg, 1997).