I;\iDCSTRIAL AND ENGINEERI,VG CHELWISTRY
May, 1924
523
Nature of the Oil of Soy Bean Miso' By Renichi Kodama IWASAKI
FOOD II&SEARCH LABORATORY, TOKYO, JAPAN
M
ISO, a soy bean paste made by fermentation, is one of the most staple and nutritious food products of Japan. All the people like it, and it is used as a soup stock and seasoning in every home. Its general analysis shows 2.66 to 11.66 per cent fat, 14.7 to 28.87 per cent protein, 5.22 to 22.83 per cent carbohydrate, and 5.44 to 12.47 per cent salt, varying according to the method of manufacture. The yearly consumption amounts to about 400,000,000 kan (1kan = 8.27 pounds), and its value is about 360,000,000 yen, or $180,000,000. So miso, being the chief source of protein, fats, etc., from vegetable sources, can be said to be an indispensable article of Japanese diet. This being the case, a thorough investigation of miso is of vital importance to the Japanese to promote their interest in national economy, as well as to improve national health and nutrition. As the matter had never been gone into in detail, the writer decided to undertake the analysis, a report of which is given. PREPARATION OF MISO For a clear understanding of the subject it is first necessary to explain briefly the usual methods of making miso. There are two varieties-the so-called Edo, or Tokyo, miso and the Sanshu, or Haccho miso. To make the former, polished steamed rice is inoculated with Koji mold (Aspergillus q m e ) and kept a t 70" to 80" F. for 3 days; then this Koji rice is mixed with steamed soy bean, salt, and water. The mixture is then put in large wooden casks, weighted down, and allowed to ferment for from 2 to 4 weeks. The resulting product is of a light brown color, with a sweet taste. The Sanshu miso is produced chiefly in the central part of Japan. It is made by inoculating the steamed soy bean with Koji mold and mixing with salt and water. This is also packed down under weights and is kept for 1 or 2 years to ferment. The result is a dark brown paste with a salty taste. TABLE I-COMPOSITION OF KIND
Rice Kokua
Soy Bean Koku
Edo Miso Sanshu a
4.4 4.2 0.0 20.0 Koku = about 5 bushels.
MIS0
Salt
Lbs. 347.5 1143.0
WATER A little
4 koku
EXTRACTION OF FATS Fresh samples of the two kinds of miso were dried in a vacuum well below 40" C. and ground to very fine powder. From this powder the crude fats were extracted with anhydrous ether by the Soxhlet method. The Edo miso was found to contain 4.85 per cent, and the Sanshu miso 11.58 per cent crude fats.
PURIFICATION The ether was evaporated in the presence of carbon dioxide. The residue was taken up in petroleum ether and the small white precipitate was removed by filtration. The filtrate was washed with distilled water until the washings showed no acid reaction. After drying the solution with sodium sulfate, it was evaporated in an atmosphere of carbon dioxide. A portion of the oily residue was decolorized with animal char coal. PROPERTIES OF MISO OILS The physical and chemical characteristics of these oils are given in Table 11. Received Decemher 26, 1923.
TABLE11-PROPERTIES OF MISO OIL -EDO MISOOILAANCHU MISOOx&Color.
Nondecolorized Greenish yellow
................ ................ ............... Liquid
Odor.. Form..
Decolorized Light yellow Soy bean oil Slight ppt.
Nondecolorized Yellow brown
Decolorized Light yellow
Semisolid Mostly PPt. solid Same a s soy bean oil Taste. Specific gravity.. 0.9471 0.9457 0.9466 0.9366 Solidification pointa., , 1 C. 120 c. 80 c. 15' C. 18' C. Melting point@. 17O C. Acid value.. 22.49 22.78 82.71 77.69 Saponification value 235.35 290.97 215.47 211.00 88.15 89.28 Iodine value.. 117.36 131.90 95.57 98.70 Hehner value.. 93.53 97.96 R. M. value 3.56 7.46 5.01 4.68 a The melting and solidifying points are not of the oil but of the white precipitate contained in the oil.
................
....... .. ........... ........... .... .......... ........ ............
...
A comparison of miso oil with ordinary soy bean oil will. be of interest. The appearance of the two oils is practically the same. The constants of soy bean oil are given in Table 111. TABLE 111-CONSTANTS Specific gravity. Melting point.. Solidification point.. Acid value.. Saponification value.. Iodine value Hehner value R. M.value
OF SOY
BEANOIL
........................... ...........................
....................... .............................. ...................... .............................. ............................. ..............................
0.9237 -7O C. -16O C. 2.07 189.21 139.56 95.13 0.27
Thus it will be seen that the acid and R. M. values are much increased, the iodine value is less, and the H e h n y value the same as in miso oil. Comparing decolorized oil with the original, it is quite evident that a great change has taken place. When decolorized, the oil becomes nearly solid and is less transparent. The iodine value is greatly decreased, while the saponification and Hehner values are greater, but the acid value is unchanged. The Edo Miso oil has less acid value, R. M. value, iodine value, and Hehner value than Sanshu, but the saponification value of the Sanshu is higher. F o u r t h International Conference on Soil Science The Fourth International Conference on Soil Science will be held in Rome from May 12 to 19 a t the International Institute of Agriculture. The first conference was held in 1909 in Budapest, the second in 1911 in Stockholm, and the third in 1922 in Prague. The program is very promising. The Italian Minister of National Economy, Professor Corbine, will be the honorary chairman. The .number of communications and reports to be presented is well over two hundred. These papers concern fundamental questions, and will help to show the intimate relationship between soil science and agricultural industry. The proceedings of the conference will be published in the form of a volume of about 1000 pages, containing all communications, conferences, reports, memoirs, discussions, etc., and will be of interest to scientific institutes and laboratories dealing with agriculture, agricultural experiment stations, agricultural colleges, and fertilizer manufacturers. The price to members for copies of the proceedings is 15 s., and to others 30 s. Further particulars may be secured from the Organizing Committee of the Fourth International Conference on Soil Science, International Institute of Agriculture, Villa Umberto I, Rome 10. Uruguay Establishes a New Import Duty-By a decree effective January 29, many drug and chemical products formerly not specified receive definite classification. The valuations applying to oils and alcohols in most cases remain unchanged. There are varying increases in the valuations on acids, essences, and on nearly all other drugs and chemical products included in this section of the tariff.
