810
THE JOURhTAL O F INDUSTRIAL A N D ENGINEERING CHEMISTRY
Vol. 14, KO.9
garin Manufacturers, published in The American Food Journal In the extraction of crude oil by pressure, about 15 per cent for &ne 1922, points out the deficiencies of the fat-soluble of the total remains behind in the press cake. We know that vitamin in butter fat in the case of rickets and shows that it can be removed by solvent extraction. It is simply a quescod-liver oil contains fat-soluble vitamins in much higher con- tion of mechanical and chemical research to substitute solcentration than they occur in butter fat. He also indicates vent extraction processes for the clumsy hydraulic presses. recent researches in analytical methods which extend the Solvent extraction produces choice oils in the laboratory, and hope that we may soon be able to identify the different bodies. with suitable apparatus can do the same in the factory. The factors involved in the rancidity of fats and best means The Department of Agriculture has started a comprehensive research on cottonseed and the products therefrom, in for preservation are important subjects for research of great cooperation with the Interstate Cottonseed Crushers’ Asso- practical value. Each of the separate problems mentioned above resolves ciation. Drs. Jamieson and Baughman of the Bureau of Chemistry have already published a method for the analysis itself into many minor ones, so it may safely be said that the of crude vegetable oils, giving the amount of absolute oil field of research in the edible fat industry is still a large one obtainable from any sample of crude by alkali refining. and well worthy of cultivation. The published results show that in refining crude oils by alkali, only 95 to 96 per cent of the available refined oil is obtainable in factory operations with existing methods. Work is now Vegetable being done to separate and identify the various impurities present in the crude oil and to determine their effect on losses By C. F. Eddy and quality of the refined oil. The same writers have also RESEARCH ASSOCIATE, RESEARCH LABORATORY OF APPLIEDCHEMISTRY, published analyses of cottonseed and peanut oils prepared MASSACHUSETTS INSTITUTE O F TECHNOLOGY, CAMBRIDGE, MASS. from authenticated seeds from many localities and pressed under known conditions in the laboratory. These results IIF. STRESS of war conditions gave the solvent esgive us the variations in the chemical constants of these oils traction industry a big impetus, especially in Europc.l?* and are far more reliable than those commonly published in The success obtained has helped to brcak down prejuthe literature. For a full statement of the work done by the dice and has stimulated ,investigation and discussion. Bureau of Chemistry, the reader is referred to a very able The higher yields obtainarticle by Dr. W. W. Skinner in the Chemical Age for June 1922. able by solvent extraction Considerable work has been done toward more accurately de- are clearly shown in a table scribing the colors of vegetable oils. A progress report of given by Shrader,2and Pickthe Committee on Color of Oil and Seed was presented before ard’s report? that in five the June meeting of the American Oil Chemists’ Society. The normal years before the war report showed a highly improved colorimeter reckntly brought a solvent extraction plant out by the Eastman Kodak Co., which makes it easily possible for flasseed gave a net return to report on the color of oils in the terms of yellow, red, and of $1 50 per ton of raw neutral tint or darkness. It is also possible to obtain color material more than for a matches impossible with previous methods. similar prewing plant, s h o w The same report gave a description of the color analyzer that the advantag& not just perfected by Keuffel & Esser, whereby it is possible to merely theoretical. obtain a spectrophotometric curve of any sample of oil, and Thiele4has recently pointed from the curve to determine whether it has been put through out another advantage of this various refining processes. It also shows the difference in h i g h e r extraction of oil. color between different oils. The instrument, needless to say, When the oil has developed adds greatly to the facilities for research. an appreciable amount of The constant requirements in manufacture call for more ex- free fatty acids, a very low act chemical information and methods, and call for travel on oil meal will be free from C. F. EDDY a little explored field. I n the analyses of the oils themselves, objectionable rancidity. I n we can separate the various fatty acids of the mixed glycerides; this connection, some have claimed that the steaming necesbut what do we know of the mixed glycerides themselves, and sary to free the meal from solvent also increases its value their structure? It is highly desirable that methods should for feed purposes. be devised for separating the different glycerides, both for Another advantage of the solvent extraction method that analytical information and the proper control of manufac- is being developed is in cnnnection with the removal of tured products. This is particularly true in the industries free fatty acid? lrom the extracted oil. I n refining by the dependent on hydrogenation. We may know the proportion same method samples of pressed and solvent-extracted of different fatty acids present, but have little more infor- cottonseed oil, Shrader reports5 refining losses for the exmation regarding the structure of the fat and its resultant tracted oil much less than for the pressed oil. I11 a previous properties, than we could obtain regarding the design of a article6 he refer. t o having tried Dr. FVesson’s suggestion building by studying the bricks and stones constituting its of refining the oil in solution instead of refining after the ruins. solvent had been removed. The only observation made I n the operating of bleaching oil by fuller’s earth, we know was a comparison of the color of the oils refined by the two little regarding the properties of the color removed, or just methods. If he was aware of thc much greater simplicity what action the earth has on the oil. We do know that the of apparatu? and method possible with refining in solution earth apparently oxidizes and polymerizes a portion of the he did not mention it, and others have secured patents on oil and removes the same in addition to the color, but why and the method.7.s The developments of processes and new types of apparahow we know not. have been very numerous, but some of them, cspcI n deodorizing the oil by steam, certain malodorous principles are distilled off. It is not improbable that these might cially some unpublished ones, have been great improvements. be developed into desirable perfumes. * Numbers in text refer t o Bibliography at end of article.
Solvent Extraction of
T
Oils
