Detoxification of cottonseed by salts and alkalies

Abstract

Summary In a series of four tests in which three deliberately chosen toxic cottonseed meals were treated with aqueous solutions of salts and alkalies, it was found that the best detoxifying effect was obtained with sodium hydroxide, followed very closely by potassium and ammonium hydroxides. Dry heat treatment alone did not detoxify, and mortality was high. Treatment with moisture plus heat gave partial detoxification. Of the 22 chemically‐treated cottonseed meal samples tested, those treated with alkalies showed the best weight gains, the order of decreasing effectiveness being NaOH>KOH>NH4OH>italicCafalse(italicOHfalse)2. The residual toxicity of treated cottonseed meals cannot be explained on the basis of their free gossypol content as analyzed for meals with high values gave better growth performance than some with lower levels of free gossypol. There were also very marked differences in final body weight after 8 weeks of feeding six different treated cottonseed meal samples having practically the same free gossypol content.

Gossypol, a Pigment of Cottonseed.

“…Since none of these condensation products have been isolated or characterized, there is some question whether they actually exist. Eagle (70,72,73) concluded that the free gossypol content of cottonseed meal is not a true measure of the toxicity of the meal; thus his opinion differs from that deduced from the results of numerous investigations (23,50,57,71,83,84,86,88,89,92,93,94,119,122,140,147,148,152,200,202,203,232,233,235) that point to gossypol as the primary toxic agent.…”

Chemical methods of evaluating protein quality

“…Cottonseed proteins show a considerable range of solubility in 0.02 N-NaOH according to treatment, and Lyman, Chang & Couch (1953) proposed a 'chemical quality index' defined as percentage of nitrogen soluble in 0.02 N-NaOH divided by either percentage of gossypol in the meal or 0.85, whichever is less, which showed a close correlation with chick-growth tests for a series of twenty-two samples. However, further work suggests that the index fails to grade meals prepared by a wider range of procedures (Condon, Jensen, Watts & Pope, 1954;Eagle, Bialek, Davies & Bremer, 1956). There is the complication in making this comparison that the different groups of workers used different types of animal-feeding tests, which might in themselves give different gradings for the same series of products.…”