Astaxanthin Extraction from Crawfish Shells by Supercritical CO 2 with Ethanol as Cosolvent

Astaxanthin is an important pigment in fish and shellfish aquaculture and increases the market value of fish such as salmon and trout. Commercially synthesized astaxanthin costs about $1,000/kg. Carotenoids have been extracted from crustacean wastes with organic solvents, but in many of the methods the pigments are degraded. Astaxanthin extraction yield from crawfish tail shells by supercritical CO2 was optimized for temperature, pressure, and moisture. The cosolvent ethanol (10% w) increased yield significantly. Temperature, pressure, and moisture content were other important independent variables. These were studied using an incomplete 33factorial (Box-Behnken) design. The equation of the model fitted to the data was extracted astaxanthin (mg/kg dry shell) = -169.3 + 5.36 T + 0.061 P + 7.32 M -0.0003 T P -0.10 T M + 0.0003 M P -0.02 T2 -0.000006 P2 -0.033M2, where T = temperature; P = pressure (psi); M = moisture. The maxima for moisture, pressure, and temperature were 13, 24 MPa, and 75, respectively.