Acidic solvent extraction of gossypol from cottonseed meal

Abstract

To expand the use of cottonseed protein in animal feeding, cottonseed meal was extracted with acetone- and ethanol-based solutions to remove gossypol. Phosphoric acid and water were included in the solutions to catalyze the hydrolysis of protein-bound gossypol. Both solvents were effective at reducing the total gossypol level in meal to between 5% and 10% of its initial value. Gossypol extraction occurred much faster in the ethanol-based extractions than it did in the acetone-based extractions. Treated meals tended to retain phosphorus but most of this could be removed by conducting a final water wash. Water washing also removed hydrophilic components resulting in reduced product yields but increased protein levels. Other acids, e.g., oxalic, citric, or sulfuric acid, were also effective at reducing meal gossypol. In contrast, extractions conducted without acid were not effective. The process can be used to produce low-gossypol cottonseed meals that should be useful in a broader range of feed applications.