SUPERCRITICAL CARBON DIOXIDE EXTRACTION OF BIXIN FROM ANNATTO SEEDS

摘要

Supercritical CO_2 extraction of the pigments from annatto seeds was carried out at a pressure of 200 bar and a temperature of 40℃ using two flow rates. The efficiency of the extraction was low for the conditions studied. However, the solubility of bixin in CO_2 modified with cthanol (5 mol %) was determined, having been verified a high increase relatively to the solubility in pure CO_2. Therefore, supercritical fluid extraction of the pigments from annatto seeds using CO_2 containing 5 mol % of ethanol was carried out at pressures of 200 and 300 bar and temperatures of 40 and 60℃. The extraction efficiency using the modified supercritical fluid was higher than that obtained with pure supercritical CO_2. The extraction yield increased with pressure and temperature. On the other hand, it decreased with flow-rate. To assess both the efficiency and selectivity of bixin extraction from a matrix with higher solute bulk concentration, an annatto preparation was obtained from annatto seeds, and submitted to supercritical fluid extraction using the same modified solvent. The efficiency of the extraction was similar to that obtained when annatto seeds were used, but the pigment concentration in the supercritical extracts was higher.