SummaryThe relative efficiencies of organic, polar solvents and of solvent‐water pairs for use in the extraction of gossypol and related compounds from cottonseed flakes were determined in a specially devised glass laboratory extractor.Of the solvents tested a butanone‐water pair containing 10% of water by volume was the most effective, and chlorine‐substituted hydrocarbons were the least effective. Under equilibrium conditions maximum extraction of gossypol was obtained with a butanone solvent containing 2.5% of water by weight. The rate of extraction of gossypol from cottonseed meal with butanone‐water pairs increased with increase in the amount of water in the system and with increase in temperature of the extraction system. The greater amounts of water in the extraction system resulted in swelling and packing of the flakes and in a decrease in extraction efficiency. Flakes extracted at 26°C. contained 0.08% free gossypol and those extracted at 71°, 0.054%. This decrease may be due, in part, to the reaction of gossypol with the protein to form bound gossypol.

SummaryProcessing conditions, particularly cooking procedures, have a marked influence on the chemical properties of screw‐pressed meal and oil. Cooking prepared meats at 240–250°F., as in normal mill practice, produced meals with low free gossypol content but at the expense of considerable protein damage. The resultant crude oils showed some color reversion upon storage at 95°F. Dry cooking (7% moisture) at temperatures not exceeding 200°F. gave meals of improved chemical properties, but the crude oils exhibited considerable color reversion on storage.Wet low‐temperature cooking (200–210°F.), followed by evaporative cooling, yielded a meal intermediate in quality between that for normal mill practice and dry low‐temperature cooking. The crude oils, which corresponded to hydraulic‐pressed oil, did not exhibit any appreciable color reversion upon storage at elevated temperatures.The selection of processing conditions, notably cooking, enables wide variations in the distribution of gossypol between meal and oil.The increase in the bleach color of crude oils stored at 95–100°F. was found to be directly related to the initial gossypol content of the crude oils.

SummaryA procedure is given for estimating the amount of intact pigment glands in cottonseed kernels and meal.The amounts of intact pigment glands, free gossypol, and total gossypol in uncooked meats, cooked meats, and press cake samples from commercial hydraulic‐press mills, a screw‐press mill, and laboratory‐scale tests were determined. It was observed that when meats were cooked with adequate moisture present, as is common in hydraulic‐press mills, most of the free gossypol was converted to bound gossypol during the cooking operation and further conversion during the pressing stage was of slight magnitude. The trend of the change in percentage of recoverable glands was roughly parallel to that of the free gossypol. By contrast, in the screw‐press mill where cooking was carried out without the addition of moisture, little change in either component occurred during cooking, but both were reduced to very low levels during passage of the cooked meats through the screw press.In laboratory tests cooked cottonseed meats were subjected to hydraulic pressures at levels of 2,000 and 20,000 pounds per sq. in. of cake surface. When meats were cooked at low moisture content, no significant change in either free gossypol or recoverable glands occurred during cooking, but hydraulic pressing at both 2,000 and 20,000 pounds per sq. in. reduced the percentage of recoverable glands. No corresponding decrease in free gossypol during pressing could be found. Wet cooking of meats decreased the percentages of free gossypol and intact glands and, although hydraulic pressing failed to further reduce the free gossypol, the percentage of recoverable glands was sharply reduced by pressing at both levels of pressure.It is suggested that the high degree of effectiveness of the screw press in rupturing and disintegrating pigment glands in cottonseed meats is due to the development of shearing forces in combination with direct or compressive type pressure. It is believed that a shearing action is more effective for this purpose than compressive force of similar magnitude.

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