TECHNOLOGY,
More Oil with Solvents A swing toward the solvent processes would favor the consumer with 1 1 % more cottonseed oil; 5 . 4 % more edible oils— estimates reveal SAN A N T O N I O . - T h e national supply of cottonseed oil could be increased by nearly 1 1 % with an industry-wâde shift from the hydraulic to the prepresssolvent process. This estimate is based on operating each process at its normal rate on 1949 to 1950 average quality seed. Similarly, all edible oils (exclusive of butter and lard) would increase by 5.4% by a similar shift. These were some results of a study on the comparative economies of cottonseed oil mills and were revealed here by J. M. Brewster of the Agricultural Marketing Section, USD A, during the annual meeting of the American Oil Chemists' Society, last week. Similar shifts to the direct-solvent and screw-press processes would increase cottonseed oil by 9% and 2 . 1 % , and all edible oils by 4 . 5 % and 1.1%. As a consequence, industry-wide shift from the hydraulic to the prepresssolvent process would reduce the price of cottonseed oil b y about 8.9%. Reductions of 7.6% and 1.8% could be effected by a swing to direct-solvent and screw-press processes. A shift to more efficient mills of any type could benefit growers in the form of higher seed prices, reported Brewster. Growers would benefit most by a shift to a more efficient hydraulic industry than b y a swing toward either of the solvent processes, although the latter would favor the consumer. Evaluating only the hydraulic, screwpress, direct-solvent, and prepress-solvent processes, Brewster said the study was too far under way to include high speed expellers and the filtration-extraction process at the time they were developed. However, the findings indicate what types and sizes of mills would constitute the most economical industry. Cost of diverting the seed from competitors, said Brewster, usually puts a relatively low limit on the sizes of mills, whatever the type. In general, for widely different specified volumes of seed, the higher oil extraction types of processes yield greater net revenue per ton of seed. Either of the solvent processes can handle a smaller crush than the hydraulic process without losing money. Filtration-Extraction. In the interest of a cheaper solvent extraction process for low annual tonnages the filtration-extraction method was developed primarily for processing 1678
cottonseed, reported J. D. Ross, Lukens Steel. It eliminates prepressing in the preparation of the seed, which permits extraction by a process designed specifically for soybeans, whose thermoplastic characteristics are such that their flakes do not disintegrate during extraction. Cottonseed is friable and requires a method of processing that can handle the inevitable fines, and at the same time render the gossypol of cottonseed a nontoxic constituent of the meal. Preparation Equipment of Process. Essentially the process utilizes conventional preparation equipment up to and including the cooking step, as found in nearly any hydraulic mill, as well as a fair percentage of screw-press mills. Cooked meats are cooled and crisped as they are fed to the extractor which, by means of internal baffling and agitating devices along with high retention time, effects solution of the oil in the solvent. The resulting slurry is conveyed to a filter where the miscella is separated from the marc. T h e marc is washed counter-currently twice with dilute miscella, and finally with fresh solvent. After draining it is discharged from the filter and conveyed to a desolventizer. The desolventized marc is cooled and conveyed to storage, while the oil rich miscella collected from the filter passes directly to a distillation system consisting of two stage evaporation followed by vacuum stripping. Miscella obtained from the filter is clear and can be handled without the use of a polishing filter. Production Equal t o Hydraulic Press Process. T h e first commercial installation at Greenwood, Miss., is currently on a production basis and since the first of the year has processed virtually the same tonnage that would have been produced had the hydraulic presses been in operation, stated Ross. To date it has more than met all of its guarantees except for residual oil content in the meal, which is presently running about 1.1% to 1.3%. Ross indicated that they were confident of substantially reducing this residual in the immediate future. Describing earlier pilot plant studies of the process at the Southern Regional Research Laboratory, E. A. Gastrock said that conditioning of meats or flakes before cooking is important, especially when processing dry seed. CHEMICAL
Last year some dry Texas seed was processed, and the filtration-extraction characteristics of the cooked material were not as good as those obtained with other seed of high moisture content. By increasing the moisture content of the flakes from 7.0% to 11 to 12% (adding part of the water normally used in the cooker), satisfactory filtration-extraction characteristics could be obtained. It so happened that seed being processed at Greenwood was very dry, and this technique proved very helpful. Large Scale Processing C o m p a r a b l e to Pilot Plant. Processing condition for commercial scale operations at Greenwood were comparable to those found practical in the pilot plant, reported Gastrock. One important difference, however, was the quantity of material processed—7100 pounds of prepared meats per hour at the commercial plant as compared with 300 to 450 pounds per hour in pilot plant runs. In terms of cottonseed per day, the prepared meat figures are equivalent 140 tons as compared with 12 to IS tons in the pilot plant, said Gastrock. Quality of the oil produced in the commercial plant at Greenwood, said Gastrock, is equal to or slightly better than oil that had been produced b y their hydraulic pressing method. Analysis showed a free gossypol content of 0.045% and a nitrogen solubility of 7 0 . 0 % - i n 0.2 Ν NaOK. These results closely approach t h e desired analyses for a good cottonseed meal (free gossypol, 0.04% or less, and nitrogen solubilities of 75% or higher) —which should be the aim of cotton seed processors in order to produce a meal that can be widely used. Molecular-Modified Lard. "It is now possible to make shortening fats from lard which equal or surpass those made from hydrogenated vegetable oil in cake baking properties," said E . W. Sordelet, Armour & Co. The major por tion of these new shortenings consists of lard which has been subjected to a chemical process resulting in a re arrangement of the fatty acid groups. Precisely what alteration has occurred we cannot say at this time, b u t physical and chemical tests leave no doubt that a change has taken place. The problem of molecular modifica tion can be accomplished in standard refinery equipment, said Sordelet. Lard employed in the reaction is first refined and vacuum dried, after which sodium methoxide catalyst is added. Re-ar rangement takes place, water is added, and the foots are removed b y centrifugation. After this process, the oil is water washed and vacuum dried, and is then ready for final processing into various types of shortening. AND
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