Defatting of annatto seeds using supercritical carbon dioxide as a pretreatment for the production of bixin: Experimental, modeling and economic evaluation of the process

In this work, supercritical CO2 extraction for defatting of annatto seeds was studied; the objective was to obtain an extract rich in tocotrienols and the defatted rich-bixin seeds. The process conditions were selected from global yield isotherms assays performed at 313 and 333 K, and 20, 31, and 40 MPa; the ratio of solvent mass (S) to feed mass (F) was 35. For this S/F the highest extraction yield was 22 mg of extract/g dried seeds obtained at 333 K and 40 MPa. At these conditions a kinetic experiment was done to estimate the required parameters needed to estimate the cost of manufacturing (COM). COM was estimated using a commercial simulator; the model SFE plant had two extractor vessels in order to simulate continuous operation. A pilot plant size unit and two industrial size units were considered. The COM decreased from 124.58 to 109.27 US$/kg of extract as the extraction vessels capacities increased from 0.1 and 0.5 m3; for the pilot plant with 2 vessels of 0.005 m3 the COM was 300.00 US$/kg of extract.

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► The SFE process defatted the annatto seeds with 85% of efficiency.
► The highest yield was 22 mg of extract/g dried seed obtained at 333 K/40 MPa.
► The optimization of cycle time decreased the manufacturing cost of extract.
► The COM were 124.58 and 109.27 US$/kg for 0.1 and 0.5 m3 units, respectively.
► The SFE process obtains seeds oil free, bixin-rich, as a byproduct.