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The results indicate that 9 to 10% moisture in the meats is the best level for the preparation of cottonseed into flakes for solvent extraction. At lower moisture the flakes contain more fines before and after agitation in solvent, and the percolation rate of solvent through a flake bed is lower because of reduced particle size. At higher moisture the amount of oil in the hulls from the beater is greater. Also the flakes produce more fines, and the percolation rate becomes slower because of the softness and pliability of the flaked meat. It is likely that in commercial continuous operations this packing or balling up tendency of the flaked meats may lead to periodic channeling or plugging in the extractor, dryer, conveyors, and filters. These conclusions have been applied in the continuous pilot plant solvent extraction of three lots of prime cottonseed. The results substantiate the findings herein and will be reported in a separate publication.

A preliminary cost study was made of a combination screw-press extraction-fractionation plant. The economic advantage of the combination plant over the screw-press operation as shown here is small in comparison with the large additional investment required for the combination plant. The present value of the combination process lies in the production of two new products, a purified high-protein meal and a concentrated pigment gland fraction and in the possibility of producing a high-grade oil as the removal of the whole pigment gland prevents the pigment material from coming in contact with the oil. Pilot-plant work under way indicates improvements in the process such as a higher recovery of the meal as purified meal. The development of additional and more profitable uses for the products would increase their value and provide a broader and more stable market for cottonseed.

Chemical engineering data are presented to show the pilotplant process development of cottonseed fractionation employing the differential settling principle. The purpose of the process is to produce a cottonseed meal fraction essentially free of pigment glands and hulls, and a second fraction in which the pigment glands are concentrated sufficiently to serve as a raw material if pharmaceutical or other industrial use is developed for the glands or the pigments. The non-lipids fraction will make available a meal of high nutritive value and a source of industrial protein. Unit operations involved, including machinery and other equipment required, and proposed flow diagrams for commercial application are discussed. In brief the unit operations are as follows: material preparation; disintegration for proper size reduction of cottonseed flakes (either defatted or undefatted) in solvent slurries; separation by tank differential settling or by centrifugal differential settling at 62 times gravity; meal recovery to recover separated fractions by either centrifuging at 1450 times gravity or by pressure filtration; desolventization of solvent-damp meal; and oil and solvent recovery.

The pilot-plant application to rice bran of a recently developed method of solvent extraction, called filtration-extraction, has been described. The process consists simply of mildly cooking the rice bran, cooling to about 130° F., slurrying the cooked bran with a miscella filtrate, filtering the slurry and countercurrently washing the cake three times on a continuous, rotary, vacuum filter, followed by conventional recovery of oil and meal products. The advantageous effects of cooking under the conditions described in the paper are reflected in the shorter filtration cycle time, better extractability, and virtual elimination of the fines problem. For example, tests showed that uncooked bran required filtration cycle times of more than 30 minutes compared to 30 to 60 seconds for cooked bran. This development makes available to the industry a feasible continuous solvent-extraction process for rice bran. Feasibility of the process is due primarily to the practical elimination of the inherently serious fines problem and to other advantages of the process, such as the possibility of attaining high capacities for small units; lower solvent content of extracted cake and of final miscella, which should decrease recovery costs; lower solvent requirements; and extraction to a residual lipides of 1 to 1.5%. Because of the reduced equipment size and simplicity of the process, it should prove economically feasible for the small and medium-sized plant, where heretofore a solvent-extraction plant required the processing of relatively large quantities of material daily.

Summary: Four oil-yielding materials, cottonseed, peanuts, okraseed, and rice bran, were used to develop a rapid method of determining the solids content of miscellas. In each case straight-line plots of the gravimetric determination vs. the volumetric determination were obtained when samples were diluted to fall within the proper range.