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Literature Cited (1) Demann, W., Brennst0.f-Chem., 14, 121 (1933). (2) Evans, E, V., and Pickard, H., "An Investigation into the Nature and Properties of Coal Tar," South Metropolitan Gas Co., 1931. (3) Eymann, W., Asphalt Teer Strassenbautech., 33,751 (1933). (4) Fricke, R., and Meyring, K., Ibid., 32, 264 (1932). (5) Green, H., J. Franklin Inst., 192,637 (1921). (6) Herschel, W. H., J. 1x11.ENG.CHEM.,14,715 (1922). (7) Hodurek, R., M i t t . I n s t . Kohlenuergasung, 1, 9, 19, 28 (1919).
Technische Hochschule, Karlsruhe,' 1931. (9) Nellensteijn, F. J., Teer u. B i t u m e n , 31, 309 (1933). (10) Nellensteijn, F. J., 2. angew. Chem., 43,402 (1930). (11) Nellensteiin, F. J., and Rodenburg, N. K., Kolloidchem. Beihefte, 31, 434 (1930). 181 Klinkmann. G. H.. Doktor-Dissertation. \-,
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(12) Nicholson, R. N., Roads and Streets, March, April, June, 1932, pp. 136, 165, 237. (13) Oberbach, J., Asphalt Teer Strassenbautech., 33, 814 (1933). (14) Pochettino, A., N u o v o cimento, [61 8,77 (1914).
(15) Riedel, W., and Weber, H., Asphalt Teer Strassenbautech., 33, 677 (1933). (16) Schrodinger, E., Ann. Physik, [4] 46,413 (1915). (17) Spilker, A., Asphalt Teer Strassenbautech., 31, 957 (1931). (18) Tietze, W., Ibid., 33, 718 (1933). (19) Ubbelohde, L., Ullrich Ch., Walter, C., Oel u n d Kohle, 11, 864 (1935). (20) Westmeyer, R., Asphalt Teer Strassenbautech., 34,291 (1934). (21) Work, L. T., Proc. Am. SOC.Testing Materials, 28,Pt.I1 (1928). RECEIVBD February 28, 1935. Condensed from a dissertation submitted by Ernest W. Volkmann in partial fulfillment of the requirements for the degree of doctor of philosophy in the Faculty of Pure Science of Columbia University.
SESAME SEED PROTEIN Fat Extractants on Solubility in Salt
and Alkali WILLIAM H. ADOLPH' AND I. LIN Yenching University, Peiping, China
N THE absence of a dairy industry which produces casein, increased attention is being devoted in China to vegetable proteins from the point of view of industrial application as well as of conserving the nation's protein food supply. Considerable attention has already been given to soy-bean protein, the so-called vegetable casein. Sesame seed, however, which contain about 62 per cent oil, also contain 20 to 22 per cent protein. Sesame oil is an important article of commerce in China, and a t present the protein remaining in the residue after the oil is removed is largely discarded or used as fertilizer. The oil is obtained either by expression with simultaneous heat treatment or by extraction with a fat solvent. Sesame protein, which Jones and Gersdorff show consists essent,ially of globulin, can be extracted from the residual oil-free cake by treatment with sodium chloride solution or other globulin solvents. If the treatment of the sesame seed during the process of removing the oil should result in denaturing the protein, its solubility would be affected accordingly. Sesame seed were submitted to different types of treatment; the results are here reported of the protein solubility in solutions of sodium chloride, hydroxide, and carbonate, and also the yield of protein obtained by different methods of coagulation.
Experimental Procedure SAMPLE. The sesame seed used were of the white variety grown in the Peiping area. The material was washed thoroughly with water and air-dried; after it was ground, the oil 1 Present address, care of School of Medicine, Yale University, New Haven, Conn. 1 J . B i d . Chem., 75, 216 (1927).
Sesame seed contain about 22 per cent vegetable protein, mainly globulin, which has properties similar to "vegetable casein," and may be applied as a plastic and an adhesive. The solubility of the sesame protein in the common protein solvents, sodium chloride, hydroxide, and carbonate, is shown to be not seriously affected by previous treatment with gasoline, or by a temperature of 110" C., while treatment with methanol causes a decided decrease in solubility especially in sodium chloride and sodium carbonate solutions.
was extracted with ether for 24 hours in a Soxhlet apparatus. It was assumed that treatment with ether a t this temperature (not over 35" C . ) does not harm the protein. TREATMENT OF THE OIL-EXTRACTED SEED. The seed from which the oil had been removed was subjected to one of the following methods of treatment: (1) Heat treatment. Forty grams of the sample were placed in an electric oven at 110' C. for 3 hours. ( 2 ) Treatment with gasoline. To 40 grams of the Sam le were added 100 cc. of commercial gasoline (boiling oint, 85" in a stoppered Erlenmeyer flask and kept at 60' for 3 hours, after which the gasoline was removed by evaporation. (3) Treatment with methanol. Same as in (2), substituting methanol for gasoline.
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SOLUBILITY.One-gram samples of the material which had been submitted to one of the above treatments were treated with 80 cc. of the given solvent solution and shaken in a thermostat for 3 hours a t 25' C., and nitrogen was determined in 25 cc. of the filtered solution by the Kjeldahl method. Sodium chloride, hydroxide, and carbonate were employed as solvents. The results of these measurements are shown in Figure 1, where the concentration of sodium chloride is expressed in normal units and that of the alkaline solvents in terms of pH value, determined in each case colorimetrically in the resulting protein solution.
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FIGURE 1. EFFECTOF TREATMENT WITH HEAT, METHANOL, AND GASOLINE ON SOLUBILITY OF SESAME PROTEIN IN VARIOUS SOLUTIONS
REPRECIPITATION OF PROTEIN.A long series of experiments was also carried out to determine the actual yield of protein obtainable by precipitation under different conditions. The oil of sesame seed was removed by treatment with gasoline a t ordinary temperature, and the protein was extracted from 150 grams of the oil-free seed with 3 liters of 0.02 N sodium hydroxide. The optimum yields of protein were obtained by applying one of the following two methods of precipitation to this alkaline solution: (1) adding 6 N acid to give a pH of 4.8,or (2) heating to a temperature of 60" C. The coagulated protein was filtered through cloth and airdried, its nitrogen content was determined, and the yield was calculated to an ash- and moisture-free basis in terms of the original protein. The average results obtained are as follows: Coagulant 6 N acid (HISO&HC1, or AoOH) Heating t o 60' 6.
Per Cent N in Protein 15.1
15.0
Per Cent Yield 51.8 43.5
The yield as calculated assumes that all the nit,rogen in the original sesame seed is present in the form of protein. The protein which separated under either of the conditions indicated coagulated in the form of a coarse curd readily retained and washed on filter cloth.
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Approximately 50 per cent of the protein (calculated as total nitrogen) which remained after the removal of fat from sesame seed was recovered. Previous treatment with gasoline as well as simple heating a t 110' C. did not interfere to any significant extent with the solubility of the globulin. Treatment with methanol, however, lowered measurably the amount of protein which could be dissolved when sodium chloride was used as the extractant. RECEIVED February 17, 1936.
