History of Soybean Crushing: Soy Oil and Soybean Meal - Part 2

by William Shurtleff and Akiko Aoyagi


A Chapter from the Unpublished Manuscript, History of Soybeans and
Soyfoods, 1100 B.C. to the 1980s


Copyright 2007 Soyinfo Center, Lafayette, California

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The earliest known removal of edible oils from oilseeds was practiced by the Egyptians before the Christian era. Historically people living in warm or tropical regions have derived their edible oils primarily from plant sources, while the early inhabitants of more temperate or cold climates have used animal fats obtained by roasting the kill and collecting the dripping fat or, later with domesticated animals, by rendering the lard or tallow (Markley 1950). However, in temperate northern China, with its high population density, both lard and oilseeds (including soybeans) have been used as sources of oils and fats since early times.

Origins and Early References . The earliest Chinese cooking fat was probably lard and China's earliest vegetable oil, sesame oil, was probably introduced prior to AD 600 (Chang 1977). Very little is known about the origin of soy oil ( douyu ) in China. The earliest known reference to it appears in the Wu-lei hsiang-kan chih , said to have been written by Su Shih in the late 11th century AD. It stated that "Soy oil may be mixed with tung oil when caulking boats."

In the authoritative Food in Chinese Culture (Chang 1977), soy oil and meal are first mentioned in connection with the Yuan and Ming dynasties (1279-1368). F. Mote, an expert on this period, notes in his chapter of the book that soy oil was probably an important edible oil and source of vitamins during this period, and that, according to the Huang ming tsu-hsun^-lu (1381), the imperial wine bureau, run by palace eunuchs, oversaw the production of soybean meal (presumably made by crushing soybeans??). Perkins (1969) believes that soybean cake appeared after 1400 and probably by 1500. Because of its use as a nitrogen fertilizer, it may have been considered more important than soy oil.

The earliest known reference to soy oil as a food appears in the Pen-ts'ao kang-mu (1578-97), China's famous and voluminous materia medica written by Li Shih-chen. The passage reads: "Yellow soybean. The flavor of soy oil is acrid and sweet. It is heating and mildly toxic. As a cure, it may be applied as a plaster on sores and to alleviate baldness." This passage was probably based on an earlier source, which was not identified.

A number of authorities ascribe an ancient origin to soy oil. Tsao (1930a), in an excellent article on China's soy oil industry, states that "In China, bean oil milling is probably as old as the history of our culinary art . . . Beans were pressed for oil long before (perhaps thousands of years) Europe came to discover this botanical curiosity." Horvath (1930), who spent many years studying the soy oil industry in China, writes: "The pressing of oil from bean seeds in China is of equally as ancient origin as the culture of the bean itself. It is to this day performed at the native Chinese mills on wedge presses, the invention of which reverts to the most distant periods in the history of technology." In 1927 he wrote that prior to 1907 soybean oil had been "used for cooking purposes by a few Chinese only." Neither of these writers cites the sources of their information.

Early Observations by Foreigners . A number of European travelers from the mid-1800s to the early 1900s commented on the use of soy oil. Yet it is interesting to note that it is not even mentioned in the long section on soybeans in the Imperial Encyclopedia ( T'u shu shih ch'eng ) published in 1728, nor in Wu Ch'i-chu^n's tome on The Soy Bean ( Ta tou ), published in Chinese in 1848. In 1855 the Baron of Montgaudry wrote that "Soybean oil is used in many ways; it is preferred to rapeseed oil and colza oil (refined rapeseed oil)." In about 1880 Eugene Simon, former French Consul in China, wrote:

Each person makes his own soy cheese. Very often, also, each person makes his own soybean oil, if not at his place, at least at his parents' place, which is usually nearby. The manufacture of oil has not become the object of a special industry, except in those townships near which there are a large number of soybean fields.

Both of these authors were cited by Paillieux in 1880. Hosie (1901), who had been in charge of the British Consulate at Newchwang, Manchuria, from 1894-1900, noted that during that period most of Manchuria's soybean exports went to southern China, through the ports of Swatow, Amoy, and Canton, where mills were erected for extracting the oil; the cake was used for fertilizing sugar plantations there and in Java. Nearly all of the soy oil exported from Manchuria was consumed in China. Carson (1909) reported that every small center of soybean production had its native mill, that soy oil was used extensively by the Chinese for cooking, and that while this oil was made mostly from yellow soybeans, it was also made from black soybeans. King (1911) reported that cottonseed and rapeseed oil, along with soy oil, were widely produced. Stuart (1911), in a materia medica based on the Pen-ts'ao kang-mu wrote that

soy oil is considered to be slightly deleterious, and is used as a local application to ulcers and skin diseases, and for removing bandoline (??) from the hair. This oil is manufactured in large quantities, especially in Manchuria, and is shipped to every part of China. It is used as food, chiefly by the poorer people, and was formerly used as a burning oil; but kerosene has now almost superseded it for this purpose. It is usually dark colored and has not a very pleasant odor.

Shaw (1911), who knew China well, wrote that for centuries the provinces of Fukien and Kwantung had imported soybean cake from Manchuria and, to a lesser extent, Shantung.

The oil is used, as a substitute for lard, in cooking. Although it is inferior to rapeseed and sesamum oils for this purpose, these oils cannot compete with it in point of price . . . In spite of its unpleasant characteristic odour and unpalatability, the poorer classes in China consume it in its crude state, but among the rich it is boiled and allowed to stand until it has become clarified.

The Japanese-run South Manchurian Railway Co. (1926) stated that

The bean milling industry was founded in China a few hundred years ago . . . Bean cake has been popular as an excellent cattle feed from old times . . . In China proper, most oil is pressed out of soybeans in private homes as a sort of side job, except in Hankow. But most imported beans from Manchuria are used for food, only little being milled for oil.

The Crush-Stone Mill and Wedge Press . The earliest known devices used in China for the commercial crushing of soybeans and expression of their oil were the crush-stone mill and the wedge press. Good firsthand descriptions of these have been given by Hosie (1901), Carson (1909), King (1911), Shih (1918), Tsao (1929), Horvath (1930) and Hommel (1937). Those by Shih, Hosie, and Tsao are the most detailed. Whole, sun-dried soybeans, preferably the variety called "oil beans," were first crushed beneath a giant stone roller (4 feet in diameter and 5-24 inches thick, that rolled like a wheel around a central pivot, being drawn by a cow or mule) or between 5-foot-diameter millstones (first a coarse, then a fine-toothed pair; hence the name "oil mill"). The flakes were then put into sacks or spread on a hempen cloth and steamed on a rack over a kettle of boiling water for about 15 minutes. Two-foot lengths of a special grass ( lai tsao ) were tied at one end then used to line the bottom of a circular bamboo or iron hoop, 4-6 inches deep and 17-18 inches in diameter. The steamed flakes were packed into this ring, stamped underfoot, to form a flat disc; 5-20 of these filled hoops were placed one above the other in vertical presses (there were also some horizontal presses), consisting of four upright 10-foot-high massive wooden pillars with cross beams at the top and bottom. Pressure was then applied by means of wedges driven in between the cross beams and beams placed on top of the frames. The wedges were struck by stones suspended from the ceiling on ropes or by wooden mallets. The oil, forced out by the heavy pressure applied for 4 hours, ran through a wooden trough and was collected in an earthen vessel beneath the press. From time to time the wedges were knocked out, another log inserted, and the wedges driven in again. The remaining flat, round cakes, typically 23-24 inches in diameter, 4 inches thick, and weighing 61 pounds (or as much as 100 pounds) each, resembling large millstones, were sun dried then stored for later use. Roughly 9% of the beans' weight was extracted as oil (Hosie 1901). As noted above, the poor often used crude soy oil whereas the rich generally boiled it then allowed it to stand until it was clarified. According to Smith (1949), at that time it was also heated in large tanks containing steam coils, then filtered.

Freshly pressed, crude (unrefined) soy oil is pale yellow. According to Lewkowitsch (1904) and Horvath (1927), if pressed from sound soybeans, it has a sweet smell and mild flavor, that is not unpleasant. On standing however, it gradually turns dark brown and, despite its abundance of natural antioxidants (tocopherols and lecithin), it eventually develops a rancid flavor (due to oxidation) and a very unpleasant odor, well known to all who have lived in China. Filtration was said to retard oil decomposition.

Production and Usage . Very little is known about the amount of soy oil produced in China in the first half of the 20th century, or of its relative importance to other oils. Perkins (1969) in discussing Chinese oilseed production from 1914-1918 does not even list soybeans as an oilseed (although 5,470,000 tonnes a year were produced), presumably because they were not widely used for oil. The major oilseeds and their average annual production were peanuts (2,260,000 tonnes), rapeseed (1,890,000 tonnes), and sesame seeds (334,000 tonnes).

Traditionally, soy oil was used both in cooking (especially for stir-frying and deep-frying) and as an illuminant. In 1929 Tsao, an authority in the field, said that in China soy oil was "perhaps the most popular oil for cooking." This seems unlikely but conceivable.

The main traditional nonfood use of soy oil was as an illuminant in homes and temples lit with wicked oil lamps. By 1929, however, it had been replaced by kerosene. Both crude and refined soy oil and rapeseed oil were used in railroad lamps in Manchuria in 1930. Shaw (1911) reported that as a lubricant soy oil was used to a very considerable extent in north China and Manchuria for greasing axles and parts of native machinery. Various Chinese writers, however, note that, since it is a semi-drying oil, it was not used in that way, unless mixed with nondrying oils. By 1930 it was widely used to make soft soaps that were known for their ability to give a good lather in hard water, which was very common in China. In about the 1920s, Lever Brothers, which had a factory in Japan, was producing soy-oil-based Sunlight Soap, which was very popular in China, even though it was somewhat expensive (Horvath 1930). By the 1920s soy oil was also being used in China in the manufacture of lacquers (it may have been used in these for centuries), paints, waterproof cloths and umbrellas, and printing inks. The soybean cakes, after being ground into a coarse meal, were most widely used as a fertilizer (Hosie 1901) primarily as a source of nitrogen and organic matter, but also for its rich content of phosphorus and potassium. It was used to a limited extent to feed hogs or cattle, then later used as fertilizer in the form of manure (Carson 1909; Shaw 1911). It was rarely made into soy flour for use in human foods, although it was used as food during the north China famine of 1920-21 (Adolph 1922).

Industrial production and trade of soy oil in China and developments with soy oil in China after 1949 under the People's Republic will be discussed in the next two sections??


The world's modern soybean crushing industry was born in Manchuria and built on exports. The development of this industry closely paralleled the rise of soybean production, as described in Chapter 3. It is not known when soybean crushing began in the three provinces known as Manchuria nor how many tonnes of soybeans were crushed during the 1800s or early 1900s. The region, however, was very sparsely populated, with only about 5 million people in 1890. Thereafter the population increased rapidly as immigration was encouraged; it reached 10 million by 1900 and 20 million by 1913. This population inflow helped fuel a soybean growing and crushing boom after 1900.

Shaw (1911) reported that for centuries soybean cake (and probably some oil and beans) had been shipped from Manchuria to Fukien and Kwantung provinces in southern China, the chief ports being Amoy, Swatow, and Canton. It was used mostly as a fertilizer on sugar plantations, but also on yams. In 1930?? Morse noted that commercial soybean crushing was probably introduced into Manchuria in about 1850, some 20-120 years after it had originated in China proper, and 15 years before Chinese ports were opened to foreign ships (Dorsett and Morse 1928-31]).

1860-1899 . According to a report by the South Manchuria Railway Co. (1926), the only oil mills in Manchuria prior to the 1860s were those used for processing hemp seeds. In the mid-1860s hemp oil mills at T'ieh-ling and Ch'ang-ch'un in southern Manchuria began processing soybeans with good results. The mills were very small scale operations, run by hand- or donkey-power. The main product was the oil; the cake was a by-product used mainly for feeding work animals and cattle. Newchwang (Niu-chuang) apparently served as the sole center for exports of soybean products, and did some oil milling as well. The earliest known statistics show that in 1864 some 443 tonnes of soy oil, 50,900 tonnes of soybean cake, and 49,300 tonnes of soybeans were exported from Newchwang, probably to China proper. In 1867 these figures had risen to 1,390 tonnes of oil, 70,300 tonnes of soybean cake, and 60,300 tonnes of soybeans.

An excellent description of the Manchurian soybean crushing and exporting industries between 1894 and 1900 was given by Hosie (1901), who was in charge of the British Consulate at Newchwang during those years. Newchwang was the only Manchurian port open to foreign trade and the only place at which reliable trade statistics were kept. The key event of this period was the Sino-Japanese War (1894-95), following Japan's invasion of southern Manchuria. After winning, Japan became the principal market for Manchurian exports, especially soybean cake, which was used as a fertilizer on rice paddies. By 1904 some 160,000 tonnes of soybean cake were being exported by Manchuria to Japan in 1904 (Lewkowitsch 1910). In 1896 Manchuria's first mechanically powered (steam-driven) roller mill, consisting of machinery made in Hong Kong, was installed in Newchwang. The soybeans were crushed between steam-driven iron cylinders, then crushed flakes were steamed, and pressed in iron screw presses using hand-turned capstan bars to extract the oil, which was sold in wicker baskets lined with waterproof paper. Most mills, however, were still the animal-powered crush-stone type, with oil expression done in a wedge press, which Hosie described in detail, stating that 100 tons of beans yielded on average 9 tons of oil.

Hosie noted that soybeans, with their cake and oil, constituted by far the most valuable item of Manchurian exports, and these exports were growing rapidly. In 1899 (1901??) Hosie estimated that 555,000 tonnes (612,000 tons) of soybeans, cake, and meal were exported from Manchuria, including 254,348 tonnes of soybeans, 236,543 tonnes of soybean cake, and 8,627 tonnes of soy oil, which passed through the Imperial Maritime Customs at Newchwang in 1899, and were worth 2.5 million British pounds--truly the wealth of Manchuria. These figures were up 12% from the year before. Hosie had observed that Manchurians used relatively little of their soy oil and cake, but he was not sure how much more than 555,000 tonnes of soybeans were produced annually in Manchuria. Prior to the Sino-Japanese War, practically all of the exported soybeans and meal had been shipped to southern China (through the ports of Swatow, Amoy, and Canton), where local mills had extracted soy oil from the beans and the cake had been used in fertilizing sugar plantations or shipped from Canton to sugar fields in Java. But by 1899 exports of these products going to Japan exceeded those going to southern China. In Japan soybean cake was replacing the traditional fish manure on rice paddies and mulberry plantations, since the falling herring catch had driven up prices, the herring fertilizer was too rich in oil, and it tended to promote breeding of insects harmful to the crops. The soybean cake, valued principally as a nitrogen source, was also fairly rich in phosphorus (phosphoric acid) and potassium (potash). Nearly all of the soy oil exported from Manchuria was shipped by steamer of junk through Newchwang to all parts of China, where it was used for both cooking and lighting. From the Yangtze River south its main competitors were peanut oil and tea oil (from the seeds of Camellia sasanqua ) (Hosie 1901).

Relatively little of Manchuria's soybean cake was used for livestock fodder, for various reasons: In East Asia not much meat was consumed because land and protein concentrates were too scarce and expensive to use them for livestock, the meal was found to be more cost effective when used as a nitrogen fertilizer, and Buddhism discouraged the eating of "four leggeds." Piper and Morse reported in 1923, however, that soybean cake or meal, mixed with soybean and kaoliang (sorghum) stalks, was used as feed for horses and mules, but only when very hard work was done. Small amounts were also used to feed work animals and hogs in China.

1900-1919 . Before the completion of the South Manchuria Railway in 1905, soybeans, oil, and cake were brought down the Liao river by junks to Newchwang. At that time Antung (Tan-tung), also a port city like Newchwang but at the mouth of the Yalu River, was Manchuria's second largest soybean milling and exporting center. In 1907, 1908, and 1909 respectively, the mills in Newchwang produced 16,926, 19,344, and 21,763 tonnes of soy oil and 175,071, 200,220, and 225,247 tonnes of soybean cake respectively. In 1909, Newchwang, still Manchuria's leading export center, exported 34,430 tonnes of oil, 324,000 tonnes of cake, and 215,400 tonnes of soybeans, all of which were grown in Manchuria. After the completion of the railway in 1905 Dairen (Dalny), a port near the railway's southern tip rapidly rose in importance until by 1909 it had almost equalled Newchwang as a soybean milling and exporting center; Antung was now a distant third. By 1911 Newchwang had 22 mills crushing soybeans, including 9 Chinese crush-stone mills driven by animals, 7 large Chinese steam mills, 5 small oil-motor driven mills, and 1 Japanese hydraulic mill. Antung had 12 crush-stone mills and 1 steam mill (Shaw 1911). These statistics show that the industry, though small and relatively primitive, was growing and modernizing.

Prior to 1914 and the outbreak of World War I, even though a fair number of mills were operating in Manchuria, soybean processing for oil and meal was a rather minor seasonal industry, operating only from October to May, inclusive. The big industries were growing and exporting soybeans. The war, however, changed everything, thrusting the soybean crushing industry into world prominence and making soy oil the soybean's most important product, again giving it precedence over soybean cake. The majority of Manchuria's soy oil was exported in unrefined from, and by far the biggest customer was the United States. As shown in Figure 25.??, exports of soy oil from Manchuria jumped from only 5,440 tonnes in 1898 to about 44,000 tonnes in 1914, up to 175-185,000 tonnes in 1918-19. US soy oil imports, mostly from Manchuria, jumped from a mere 6,000 tonnes in 1914 to a whopping 165,000 tonnes in 1918 (Page et al. 1920). Europe's imports of soybeans and soy products during the war were reduced to almost nothing since it was too dangerous for foreign ships to enter the strife-filled European seas. The booming US demand for soy oil, which continued until 1920, led to a major expansion and modernization of the Manchurian soybean crushing industry.

1920-1940 . After the war, America's newly established soybean industry realized that American farmers could be growing the soybeans that were being imported from Manchuria. Thus in 1921 a stiff tariff was imposed on Manchurian imports; it virtually closed the American market to Manchuria, dealt Manchuria's expanding crushing industry its first heavy blow, and led to a brief postwar slump. Fortunately, starting in the early 1920s, Europe began to import increasingly large quantities of soy oil, with Germany, the Netherlands, and England being the leading importers. China and Hong Kong were also major oil importers from 1925-1935. Most of the actual oil exports were handled by foreign shipping firms, which reaped the majority of the profits. Virtually all of the exported oil was in its crude (unrefined) form. After extraction it was allowed to settle, then filtered and pumped into iron tanks for storage. Abroad, it was used mostly for industrial products (soaps, paints, etc.) with only a small percentage going into food uses. Some refined oil was also produced. In 1921 the Japanese-owned Nisshin Oil Mills at Dairen and Yokohama purchased oil refining equipment from the US and by 1927 was producing 20 tons?? a day of Superior Salad Oil from soybeans at Dairen. In 1923 the Anglo-Chinese Trading Company at Harbin also started refining soy oil to make Acetco Salad Oil, which by 1927 was said to be equal to the best Wesson oil (Horvath 1927).

In 1923 Kempski reported that Dairen, Manchuria's leading soybean crushing center, had 72 mills and a daily capacity of 225,000 soybean cakes (each weighing about 61 pounds). In 1922 Dairen produced more than 28 million cakes; all of the mills were press mills except the Luzaki mill. Manchuria's total output in 1922 was 55 million cakes (1,521,818 tonnes) and 333.3 million pounds (151,184 tonnes) of soy oil. The great majority of the oil was exported to Japan and Europe, with only a small portion being used in Manchuria for food and industrial purposes. Manchuria's main oil customers in 1919 were the US, Japan, and England, in that order. In 1921, after the US tariff was passed, they were the Netherlands, England, and the US.

In 1926 the Japanese-run South Manchuria Railway Co. published a 40-page report, Soya Beans in Manchuria , containing detailed statistics plus many good photographs of soybean production and processing for oil and meal. It was calculated that of the 3.87 million tonnes of soybeans produced in Manchuria, 48.6% were crushed for oil and meal; 41.1% of the oil and meal was exported and 7.5% was consumed domestically. Thus total oil production was estimated at 188,300 tonnes (398.2 million pounds). The four largest processing centers (all ports) were Dairen (by far the biggest), Harbin, Antung, and Newchwang (Yingkow??). In Manchuria there were 447 oil mills using 9,937 hand-turned screw presses, 2,728 hydraulic presses, and 362 primitive wedge presses. Together they produced 1,587 tonnes of oil and 528,000 soybean cakes per day. From 75-92% of the oil and soybean cake exported were produced in south Manchuria. The great majority of the cake was exported to Japan for fertilizer, with small amounts going to China proper and Korea for the same use. A very small amount was shipped to Europe and the US for cattle feed. The main oil importers, in order of importance, were China proper, England, Italy, and Holland. By 1930 some of the world's most advanced research on soy oil was being conducted at the laboratories of the Japanese-run Chinese Eastern Railway and the South Manchurian Railway in Manchuria. Yet further refining or processing of the crude soy oil to make additional products was very undeveloped, so crude Manchurian oil was shipped overseas then imported back as margarine, soap, candles, glycerine, rubber articles, printing ink, waterproof goods, paint, varnishes, linoleum, etc. Horvath (1930) urged the people of Manchuria to learn to produce these foods themselves.

Exports of soybean cake paralleled those of oil, reaching a peak of 2.07 million tonnes in 1927; 76% of this total was imported by Japan and 23% by China. The Manchurian cake was too high in oil and water content to be shipped through the tropics to Europe without excessive spoilage and shrinkage. Some cakes were imported by the US in the form of "beanboards," which contained less oil and moisture than the typical cakes. These were used mostly in chicken feeds. US imports reached a peak of 50,000 tonnes in 1937, but fell to zero by 1939, as the US became self-sufficient in soybean meal.

During the early 1920s Manchurian exports of soy oil and cake climbed dramatically, reaching a peak in 1926, which was followed by a second market collapse in 1928 (Fig. 25.X). There was very little information during this period about total soy oil production in Manchuria. Horvath (1927), studying soy oil in Manchuria, calculated that in 1926 the country was producing 181,000 tonnes (399 million pounds) of soy oil and 1,385,000 tonnes of soybean cake (50 million millstone-shaped pieces). This implies that in 1926 Manchuria was crushing at least 1.6 million tonnes of soybeans and recovering about 11% of the total weight in oil. And the country was exporting almost 90% of its soy oil. In 1930 Horvath calculated processing capacity to be 1,269,800 tonnes of soybeans, but other evidence suggests that 1.5 million tonnes or more would be more realistic. According to the Japanese publication Contemporary Manchuria (1937a), Manchuria was growing 5,000,000 tonnes of soybeans that year and crushing half of these. However, given the plummeting exports, a crush of less than 2 million tonnes seems more realistic. In short, between 1918 and 1939, the Manchurian crush, in its heyday, probably ranged from 1.5 to 2.5 million tonnes. It was not until 1942 that the USA passed this top figure.

There were various causes for the collapse of 1928. Europe, which had now rebuilt and expanded its oil processing capacity, found it more economical to import whole soybeans from Manchuria and process them into oil and meal locally. Using modern solvent extraction systems, the European mills were able to extract a larger percentage of the oil in soybeans than was possible using antiquated Manchurian hydraulic presses. Moreover, processing in Europe produced a higher quality and lower cost soybean oil than the often rancid oil shipped in leaky 5-gallon tins from Manchuria, and a much higher quality, lower-fat meal. Exports of soybean cake to Japan had also been hurt, primarily by the increased popularity of chemical fertilizer (ammonium sulfate), which was less expensive and easier to apply, and by the development of the nitrogen fixation industry making inoculants for soybeans and other legumes.

The crash of oil exports from Manchuria in 1928 took a heavy toll on the local industry. In 1918, at the peak of World War I, there were 300 oil mills of various sizes in Manchuria; after 1928 many of these suspended business. By 1930 the number had fallen to 150; 41 in Dairen, 39 in Harbin, and the remaining 70 in other cities, mostly along the railways or in ports. Two-thirds of the mills were in southern Manchuria. In 1928 a delegation of Manchurian oil mill owners went to Hamburg to study the problem and learn how to modernize (Tsao 1929 and 1930a). By 1930 an Oil Mills Association of Manchuria had been formed. Results were good and by 1932 Manchuria had managed to recoup some of its losses, yet thereafter there was a steady decline, which fell to almost zero at the beginning of World War II. After the war, the US took over the position that Manchuria had so long occupied as the world's leading exporter of soy oil. Manchuria was no longer heard of.

Changing Types of Mills and Efficiencies . As Manchuria's soybean crushing industry developed, the types of mills and presses used constantly changed, as noted briefly above. Prior to 1896 all of the mills had used primitive crush-stones and wedge presses. With the introduction of the first steam roller mill at Newchwang in 1896, the wedge presses also began to be changed, first to hand-turned screw presses and then to the much more powerful hydraulic presses, many of which were steam activated. Dairen's first steam mill was in operation prior to 1909 at the Nisshin Bean Mill. Yet old-fashioned methods using cheap labor were often found to be more profitable than capital-intensive modern methods. Thus as late as 1937 wedge presses were still used at small mills in remote interior districts; hand-turned screw mills were the most popular nationwide, but hydraulic presses with steam-powered roller mills were used by the majority of mills in the main production centers such as Dairen. Two big mills (Nisshin Oil Mills at Dairen and Anglo Chinese Trading Co. at Harbin) were using an improved, higher-pressure rectangular plate hydraulic system, and two mills were using solvent extraction.

The world's first solvent plants were developed in Europe prior to 1920. When?? The Suzuki Bean Mill (later Hohnen Oil Mills) had started Manchuria's first solvent extraction at Dairen prior to 1922 (probably prior to 1914?? Contemporary Manchuria 1937) using benzene extraction and equipment patented in Germany. By 1923 the Hohnen Oil Mills had a capacity of 80 tons of soybeans a day (Piper and Morse 1923) and by 1937 a capacity of 700 tons a day. The first studies on solvent extraction using alcohol (ethanol) were done in 1927 at the Central Laboratory of the South Manchuria Railway Company at Dairen. Extensive research was done by Japanese investigators: Sato et al. (1928-32), Okano et al. 1929), Mahino (1929), and Ohtomo (1937; these 4 need Refs??). By 1937 the hot alcohol process was used commercially at the Manchurian Soyabeans Industry Company's 100-ton plant at Dairen. The meal and lecithin were sold under the brand name Soyalex. The meal, containing 0.5-1% oil, was used in making shoyu (Japanese-style soy sauce), miso, candy, noodles, and Ajinomoto (monosodium glutamate); it sold at a 25% premium price over other meals. Chinese were reported to prefer the flavor of alcohol-extracted, unrefined oil to that refined with benzene or benzol. The main advantages of the alcohol extraction method were the ease of by-product recovery, the superior quality of the oil and meal, and the fact that ethanol was the most readily available solvent there, and could be produced domestically by fermentation. The disadvantages were the higher cost of alcohol over some imported hydrocarbon solvents, the higher temperature to which ethanol had to be heated, and its greater latent heat of evaporation ( Contemporary Manchuria 1937b; Goss 1941; Markley and Goss 1944). In 1937 the cost of setting up a solvent extraction plant with a capacity of 100 tons of soybeans per day was 6.5 times as great as setting up a hydraulic plant with the same capacity ( Contemporary Manchuria 1937). Virtually all of the oil mills in Manchuria were owned by Chinese/Manchurians; however many of the larger mills (Hohnen, Nisshin, Mitsubishi, etc.) were Japanese owned.

With each modernization of the systems, oil extraction efficiency improved. Tests reported by the South Manchuria Railway Co. (1926) and by Tsao (1929) showed that on average 100 kg of Manchurian soybeans contained 17 kg of oil (range 14-19 kg). Commercially, from 100 kg of soybeans, one could obtain 10 kg (59%) of oil by the round cake hydraulic system, 12 kg (70%) by the rectangular plate hydraulic system, and 14-15 kg (82-88%) by the solvent extraction system. Thus one could obtain 40-50% more oil by solvent extraction than by standard hydraulic presses, a huge increase in efficiency. Moreover, the less the oil in the cakes or meal, the greater their value as fertilizer, since oil retards the growth of young plants. Solvent meal contained only 1.5-2% oil versus 7.2% for round rakes.


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