SUPERCRITICAL CARBON-DIOXIDE EXTRACTION OF COTTONSEED WITH COSOLVENTS

Extraction of cottonseed lipids with supercritical carbon dioxide (SC- CO2) was conducted with and without a co-solvent, ethanol or 2-propano l (IPA). At 7000 psi and 80 degrees C, the reduced pressure, temperatu re and density of SC-CO2 was at 6.5, 1.17 and 1.85, respectively; the specific gravity was 0.87. Under these conditions, CO2 is denser than most liquid extraction agents such as hexane, ethanol and IPA. The ext raction of cottonseed with SC-CO2 gave a yield of more than 30% (moist ure-free basis). This is comparable to yields obtained by the more com monly used solvent, hexane. The crude cottonseed oil extracted by SC-C O2 was visually lighter than refined cottonseed oil. This was substant iated by colorimetric measurements. No gossypol was detected in the cr ude oil. However, crude oil extracted by SC-CO2, to which less than 5% of ethanol or IPA as co solvent was added, contained ca. 200 ppm of g ossypol, resulting in the typical dark color of cottonseed crude oil w ith gossypol. CO2, extracted a small amount of cottonseed phosphatides , about one-third of that extracted by pure ethanol, IPA or hexane. A second extraction with 100% ethanol or IPA after the initial SC-CO2 ex traction produced a water soluble lipid fraction that contained a sign ificant amount of gossypol, ranging between 1500 and 5000 ppm. Because pure gossypol is practically insoluble in water, this fraction is bel ieved to be made up of gossypol complexed with polysaccharides and pho sphatides.