CONCERNS FOR THE DETERMINATION OF FREE FATTY-ACID IN COTTONSEED

The official AOCS method for the determination of free fatty acid (FFA ) in cottonseed requires dehulling the seed, grinding the meats with a 12-blade food processor, and extracting the ground meats in a butt tu be with three portions of room-temperature petroleum ether. The extrac ted oil, after desolventization, is then titrated with NaOH to the end point of phenolphthalein in a mixed solvent of isopropanol and hexane . Our study showed that this procedure tends to underestimate the amou nt of FFA present in the oil of cottonseed by as much as 11.5%. It was also found that to obtain consistent and accurate FFA content, a desi rable particle size is smaller than 10 mesh (preferably <14 mesh), min imum extraction temperature should be no less than 40 degrees C (prefe rably greater than 50 degrees C), and the extraction time should be lo nger than 2 h in a Soxhlet extractor.