The highest extraction yields of chlorophylls are obtained at 250 bar – whereas the highest extraction yield of total carotenoids Fig. 4. Yields (average ± standard deviation) of (a) total carotenoids and (b) chlorophylls a, b and c, after SFE with various co-solvent concentrations, at 40 C, 250 bar and 2gCO2 min1, for 240 min.
A.C. Guedes et al. / Journal of Food Engineering 116 (2013) 478–482 481 is observed at 200 bar; increase of pressure apparently favors extraction efficiency. The most appropriate operating temperature, at 250 bar, to attain the highest yields of chlorophylls is 40 C – but the highest carotenoid yield occurs at 60 C. Moreover, the extraction yields decrease with CO2 flow rate, at constant pressure and temperature – except in the case of chlorophyll a. Finally, presence of ethanol at 7.7% (v/v) increases both carotenoid and chlorophyll yields relative to plain CO2. Consequently, the proper selection of operating conditions for SFE depends considerably on the target compound (or compound family) – and polarity should, in particular, be taken into account.