Gossypol in cottonseed products: toxicology and inactivation

The little attention given to the potential of cottonseeds as food for monogastric animals and man is due to the presence of toxic principles in them, especially gossypol. The injury to livestock associated with ingestion of cottonseeds results from the unfavorable physiological effect of gossypol per se, as well as from its adverse effects on the protein nutritive value of the food (mainly by rendering lysine metabolically unavailable). Various approaches have been employed to overcome these problems, by removing the gossypol glands, growing glandless varieties, extraction of gossypol with solvents, or through inactivation by heat processing, reacting with cations or with certain organic compounds. In this study the phospholipid fraction (gums) derived from soybeans, which is relatively rich in phospholipids containing a free amino group, was used with a view to lowering the tendency of gossypol to bind with lysine, and at the same time to inactivate the gossypol by converting it into a bound form. Dehulled and flaked cottonseeds were mixed with 5% soybean gums and 0.5% NaOH, in a laboratory cooker resembling the apparatus used in the cottonseed processing industry. The meat was cooked for different periods and at several temperatures. Later the oil was extracted with hexane and the meal was tested for free gossypol, "available lysine" and protein nutritive value, in comparison with a control batch treated similarly but without gums. The results proved the superiority of the meal treated with gums, as evidenced by all the above parameters.