Gossypol cottonseed

A protocol approved by the FDA to determine the safety of low gossypol cottonseed kernels for human consumption was the basis for the second study by Reber (7 ). To prepare raw cottonseed flour, raw kernels were ground to meet Ro-tap sieve specifications of lab chow. To prepare roasted cottonseed flour, raw kernels were dry roasted at not less than 121°C for not less than 5 min. To prepare cooked cottonseed flour, raw kernels were cooked in steam until batch temperature had been at or above 121°C for 5 min. All cottonseed kernels were ground in the manner described above. The kernels contained not more than 0.037% (370 ppm) of free gossypol. They were free of Salmonella and did not contain detectable amounts of aflatoxin. The proximate analyses of the cottonseed flours are shown in Table I. 

Since feeds contain other substances than those required by the animals of interest, studies have also been conducted on antinutritional factors in feedstuffs and on the use of additives. Certain feed ingredients contain chemicals that retard growth or may actually be toxic. Examples are gossypol in cottonseed meal and trypsin inhibitor in soybean meal. Restriction on the amount of the feedstuffs used is one way to avoid problems. In some cases, as is tme of trypsin inhibitor, proper processing can destroy the antinutritional factor. In this case, heating of soybean meal is effective. 

Glanded cottonseed kernels contain 1.1—1.3% gossypol (19) plus related pigments that affect nutritional properties and color of the oil and meal. Cottonseed also contains the cyclopropenoid acids, malvafic and stercuhc acids, which exist as glycerides and are concentrated in the seed axis (32). 

Raw defatted cottonseed flours contain 1.2—2.0% gossypol [303-45-7] (7) (19). When cottonseed is treated with moist heat, the S-amino group of lysine and gossypol forms a derivative that is biologically unavailable thereby inactivating gossypol but further lowering the effective content of lysine. 

Use of some oilseed proteins in foods is limited by flavor, color, and flatus effects. Raw soybeans, for example, taste grassy, beany, and bitter. Even after processing, residues of these flavors may limit the amounts of soybean proteins that can be added to a given food (87). The use of cottonseed and sunflower seed flours is restricted by the color imparted by gossypol and phenoHc acids, respectively. Flatus production by defatted soy flours has been attributed to raffinose and stachyose, which are removed by processing the flours into concentrates and isolates (88). 

The Food and Drug Administration approved the use of cottonseed containing not more than 450 ppm gossypol for human use. Glandless whole kernel cottonseed flakes and cot-n-nuts are commercially available. 

Studies incorporating cottonseed into many different foods have yielded acceptable products with improved protein quantity and quality. The presence of free gossypol and cyclopropenoid fatty acids (CPFA) potentially limits the use of cottonseed in human foods. 

Glanded cottonseed has been used to produce a defatted cottonseed flour with reduced gossypol content by a procedure known as the liquid cyclone process (LCP). LCP cottonseed flour has been used in the preparation of many foods that have been tested in several animal and human nutrition studies. The commercial production of LCP cottonseed flour has not been successful (5). 

Reber, E. F. Hopkins, C. F. Liu, M. M. Gossypol content of cottonseed products processed for human consumption. Paper presented at the 44th Annual Meeting of the Institute of Food Technology, Anaheim, Ca., June 10-13, 1984. Abstract 9, p. 91 in Program. 

The concept of torsional asymmetry is not jnst an interesting abstract idea. Some years ago, fertility in some Chinese rnral commnnities was found to be below normal levels, and this was traced back to the presence of gossypol in dietary cottonseed oil. Gossypol acts as a male contraceptive, altering sperm matnration, spermatozoid motility, and inactivation of sperm enzymes necessary for fertilization. Extensive trials in China have shown the antifertility effect is reversible after stopping the treatment, and it has potential, therefore, as a contraceptive for men. 

The importance of pigment glands as sources of toxins in cottonseed was suspected early in the twentieth century. In 1915 Withers and Carruth ( showed that the toxicity of cottonseed to animals was due to the compound gossypol localized in pigment glands. 

The one product obtained from cottonseed oil, Gossypol which is categorized as non-hormonal selective spermatogenesis suppressant, is effective in producing azoospermia or severe oligospermia but it is not widely used as male contraceptive. Mechanism of action is not known. Adverse effects are edema, diarrhoea, hypokalemia, neuritis. 

One of the aldehyde groups of the gossypol is believed to react with the primary amine of the lysine units of the cottonseed proteins to form the Schiff base or imine type compound as shown at the top of Figure 12 (16, 17). An analytical method for determination of bound gossypol, developed by Pons et al. 

Figure 14. UV spectra of (A) gossypol-amino reaction mixture and (B) extract from aminopropanol treatment of water and salt-solution insoluble fraction of LCP cottonseed flour (4)...

The seven major flavonoids in these flours were isolated and identified as 3-0-glycosides of kaempferol and quercetin. The marked brown discoloration observed when LCP glanded cottonseed flour is used in a food product is caused by bound gossypol and at least two bound gossypol-like pigments. The brown color observed when glandless cottonseed flour is used in food is believed to be due to other phenolic constituents that are either insoluble polymers or are bound to the insoluble plant polysaccharides. 

---