Soy

SOY, a plant belonging to the legume family (Leguminosae). The homeland of soy is Manchuria, Northern China, Japan, Korea, India, where it has been cultivated since ancient times. In the USSR, S. is cultivated in the southern regions, where it is known under the names "soybeans", "oil pea", "oil beans" and others. The most favorable area for cultivating S. is the most moistened steppe regions of the North Caucasus region. Early varieties of S. can mature around Rostov, in many places in Ukraine, in Primorye and other places in the USSR. The number of varieties of S. is very large, all of them come from wild S., which is very widespread in the Far East. Cultural varieties of S. differ from wild ones in their thick, strong stems with numerous lateral branches. Varieties of S. differ in color, in the shape and arrangement of flowers, pods, seeds and leaves. Different varieties have different taste qualities and yield. Beans belong to the number of nutritious food products containing a lot of protein and fat. Depending on the variety of S., as well as the place of its growth and other conditions, its chemical composition varies greatly. On the basis of numerous analyses of different varieties, the following limits can be accepted for the content of the main components of S. and the following average composition (according to Iol'son). Components Moisture Raw protein . . . . Raw fat....... Nitrogen-free extractive substances . . . Raw fiber . . . Mineral substances Total . Minimum Maximum Average on wet substance | on dry substance 5.5 30.0 10.0 On dry substance 24.0 14.0 22.0 3.0 4.0 60.0 25.2 32.5 12.0 6.3 36.5 17.5 26.0 4.5 5.5 40.5 19.5 29.0 5.0 6.0 100.0 The main protein of S. is globulin glycinin, which is close in hydrolysis products to the proteins of cow's milk and meat. Glycinin is often called vegetable casein, because it is similar in properties to casein of cow's milk. Regarding the carbohydrates contained in S., it is necessary to note the small amount of starch, which makes S. valuable as a material for the nutrition of diabetics. Regarding mineral substances, soy is significantly richer than other legumes in phosphorus content (according to Bowers - 0.649% phosphoric acid). Among vitamins, vitamins A, B and B have been found in S., whose presence has been established by animal nutrition experiments. Soy oil, obtained by extraction of soybeans, contains vitamin D, and when the oil is obtained by pressing, vitamin D remains completely in the meal (cake). In S. sprouts, vitamin C is contained in a significant amount. There are indications of the presence of vitamin E in S. (Daniels and Hutton). Among enzymes, S. contains urease, lipase, diastase, uricase, protease, peroxidase. The ureolytic action of S. is not a result of bacterial action, since even sterilized beans have a strongly expressed ability to decompose urea. An aqueous extract of S., containing urease, is a reagent for the quantitative determination of urea in urine and blood. Under the influence of diastase contained in S., starch gives ²/₃ sugar and 7₃ dextrin, while the diastase of barley malt gives significantly less sugar and more dextrin. On this basis, a patent was even taken out for the manufacture of yeast from soy. The nutritional value of soy is determined primarily by its chemical composition. Soy contains almost twice as much protein as beef. The methods of food use of S. are extremely diverse, the digestibility of rationally prepared soy dishes is very high. According to the data of Prof. London, the relative nutritional value of soy dishes compared to meat-fish dishes is: for proteins and fats - 88%, for carbohydrates - 100% and for fiber - 55%. However, it must be borne in mind that in Prof. London's experiments, exclusively dishes prepared from boiled soybeans were used, while the experience of the East shows that to increase the digestibility of S., it is necessary to extract from the whole grain water-soluble proteins and other nutrients, and then, after obtaining soy "milk", prepare the product "tofu", which is the basis for preparing a whole range of dishes that resemble meat and fish dishes in taste. By this method of processing S., it is possible not only to convert soy protein into a more digestible form, but also to remove substances that give S. a specific smell and taste. Soy milk, rich in the main nutrients, has long been widely used in the countries of the East. According to Japanese and Chinese authors, the protein of soy milk is physiologically complete. According to the data of the All-Ukrainian Institute of Nutrition (Kharkov), soy milk contains twice as much protein as women's milk, and twice as much albumin as cow's milk. The All-Ukrainian Institute of Nutrition came to the conclusion that soy milk, in terms of its chemical composition and its effect on a healthy and sick person, can be considered a very valuable food product. However, a significant drawback of soy milk is its unpleasant taste, which is why in the USSR soy milk has been used only as raw material in the confectionery industry until recently. But soy milk is so rich in the most important nutrients that its scope of application can and must be significantly expanded. In 1931, the microbiological laboratory of the Soy and Special Crops Institute solved the problem of obtaining a number of lactic acid products from soy milk - curdled milk, lactic acid cottage cheese, koumiss, etc. (Belen'kii, Popova). In the same laboratory, a bacterial method for obtaining soy tofu was developed, which makes it possible to do without the use of calcium chloride and other salts. The fiber contained in soybeans is completely absent in soy-milk products, which contributes to their easy digestibility and gives them the properties of dietary products. The possibility of obtaining the above fermentation products from soy milk so expands its scope for the needs of public nutrition that the question of the food use of S. is now being posed by the People's Commissariat of Agriculture and the People's Commissariat of Health in a completely new way. In 1933, in Moscow, Odessa, Rostov-on-Don and other cities, factories and workshops for the mass production of lactic acid fermentation products from soy milk have been equipped and are being equipped. Soy oil has mainly technical application. As a food product, soy oil has been used since ancient times in the Far East countries. Unrefined soy oil, prepared by primitive methods, has an unpleasant smell and taste, spoils quickly and when used as food can cause heartburn and stomach diseases. Refined oil, however, is completely devoid of unpleasant odor and with proper storage is no less stable than any other vegetable oil. In refined form, soy oil has become widespread in North America and Europe as a salad oil, as well as for the production of margarine. By hydrogenation of refined soy oil, edible lard can be obtained, which is produced in the Far East under the name "salamas". When extracting soy oil from soy grain by a special Bolman method (extraction with a mixture of alcohol and benzene), lecithin is obtained as a by-product, the content of which in S. ranges from 1-2%. Soy lecithin can be used in the production of pharmaceutical preparations, in the confectionery and margarine industries, where it replaces egg lecithin. Soy flour is used in China and Manchuria as an additive to the main flour when baking flatbreads. Freshly ground soy flour has a pea flavor, and after some time a bitterness appears in it. When preparing soy flour by improved methods, it can be deodorized and made suitable for long-term storage. Soy flour prepared by the Bertzel method (treatment with saturated water vapor) has no unpleasant taste and can be used in baking, in the confectionery industry and in public catering. Baking bread from soy flour alone is impossible, as it does not contain gluten and starch. From soy flour, cereal is also prepared, which can also be deodorized and used in public catering. Soy sauces ("shoyu", "tamari", "soy-kabul" and others) are widely used as seasonings by the peoples of the Far East, from where they have also penetrated into Europe and America. These sauces are products of fermentation of S. and are prepared from S. with the help of "koji" - a culture of a special fungus (Aspergillus oryzae) on boiled rice. According to Japanese authors, soy sauces have a beneficial effect on digestion due to the presence of various enzymes and histamine in them, which stimulates the action of intestinal muscles. It should also be mentioned about "miso" and "natto", products of fermentation of soybeans, widely used by Japanese as an addition to various dishes. Among other food products, one can also mention soy coffee, soy cocoa and chocolate, preserves from immature S. ("green peas") and soy sprouts, rich in vitamin C and which may be important in supplying northern regions and polar expeditions.

Soybeans are very sensitive to storage conditions and with excessive moisture quickly spoil under the influence of the life activity of various mold fungi and bacteria. Therefore, the storage facility for S. should be dry, possibly more frequently and better ventilated. The temperature during storage should be as low as possible. The height of the layer of S. during storage should be the less, the moister the S. Soybeans with a moisture content of over 16% can be stored only in a bulk pile on the floor, not more than 30 cm thick, or in bags. When transporting S., the moisture content of which does not exceed 14%, cars can be used to full capacity. With higher moisture content, it is best to transport soy only in winter in a frozen state.

D. Bepepel'skiy. In bacteriological technique, soy is used for preparing nutrient media. The composition of soybeans includes protein substances (30-45%), carbohydrates (22-29%, depending on the variety and degree of maturity of the soy), fats (15-23%) and mineral substances (2-6%), mainly potassium and phosphorus, in significantly smaller quantities calcium. Thus, S. contains everything necessary for growing microbes; the protein substances of S. are chemically and biologically close to proteins of animal origin. Nutrient media are prepared from S. in its pure form or from S. in combination with yeast or yeast and lactic acid bacteria. The growth of bacteria on soy media is more abundant than on ordinary nutrient media. Preparation methods: 100 g of soybeans is poured with 600-800 cm³ of water; after 24 hours, the mixture is placed in an autoclave at 120° for 2 hours. Then the liquid is decanted from the sediment, 1% peptone and 0.5% NaCl are added to it, and after establishing the reaction, it is again boiled in an autoclave at 120°. The resulting broth is filtered, poured into appropriate dishes, and sterilized at 120°. On the broth obtained by this method, after dilution 2 or 4 times, agar is prepared in the usual way. Soy-yeast agar is prepared from a decoction of S. and autolyzed brewer's yeast. 30 g of soybeans is poured with 1 l of distilled water and placed in an autoclave at 120° for 20-30 minutes; the mixture is filtered through paper or cotton and topped up with distilled water to the original volume. Then 0.5% NaCl is added, sterilized at 120° for 30 minutes. Liquid brewer's yeast is heated to 50° with constant stirring and left in an incubator at 45° for 18-24 hours; it should be diluted with tap water at the rate of 3 l of water per 2 l of yeast, thoroughly mixed, and sterilized at 120° for 30 min. To prepare agar, the transparent layer of yeast decoction is decanted from the sediment; it is then mixed with an equal amount of soy decoction, the required reaction is established; then agar is prepared in the usual way. In order to obtain a nutrient medium suitable for preparing strong toxins and for differential diagnosis and study of the biochemical properties of microbes by adding appropriate carbohydrates, it is recommended to first remove the carbohydrates contained in soybeans. For this purpose, the method of treating S. with yeast and lactic acid bacteria is recommended. For 1 l of tap water, 200 g of soybean flour and 50 g of sourdough (yeast + lactic acid bacteria) are taken, thoroughly mixed and placed in an incubator at 37°. After 24 hours, it is neutralized with a normal NaOH solution, 1% HCl and 0.2% dry pepsin are added, mixed, and inactivated at 50° for 48 hours. After this, an equal amount of water is added, filtered through gauze and then through cotton. The filtrate is heated to 80° and neutralized with a normal NaOH solution to neutral reaction by litmus, filtered again, the required reaction is established by an ionoscope, 0.5% NaCl and 0.2% phosphate salt are added, mixed with egg white, boiled, and after filtering and pouring into the required dishes, sterilized in an autoclave at 172-atmospheric pressure. The resulting transparent medium has the color of concentrated broth. The best growth of microbes of the intestinal group is observed when the medium is diluted 1:4. Loeffler's bacilli grow better when diluted 1:2, gonococci and streptococci - when the main solution of S. is diluted with ascitic fluid twice. A. Korzhinskaya.