Compositional characterization of cottonseed soapstocks

Cottonseed soapstock samples, collected during the 1993-1994 crushing season from oilseed extraction mills throughout the United States Cotton Belt, were analyzed by chemical and chromatographic methods. Volatiles averaged 48.7 ± 10.6% (mean ± SD, n = 39). On a dry basis, the samples averaged 33.3 ± 7.3% fatty acids, 26.3 ± 6.9% phospholipids, 8.4 ± 6.4% triglycerides, and 7.5 ± 3.0% gossypol. The analytical techniques accounted for 93.3 ± 8.6% of the dry soapstock matter. The AOCS method for total fatty acids in soapstock yielded values in agreement with the chromatographic and phosphorus analyses. In contrast, the AOCS method for neutral oil in soapstock gave values that were significantly higher than those obtained by chromatography. The amount of nonlipid material in the samples correlated with the phosphorus content. Total gossypol and nitrogen levels were also related.