History of Soybean Crushing: Soy Oil and Soybean Meal - Part 1
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A Chapter from the Unpublished Manuscript, History of Soybeans and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
Unlike the seeds of most other legumes (except the peanut), the soybean is rich in oil, and is often called an "oilseed." The value of the soybean, which contains about 18% oil and 35% protein, lies in the fact that there is a strong demand for both these ingredients, either directly or indirectly, in human foods. The separation of these two major components has given rise to the soybean crushing industry.
The great majority of the world's soybeans are processed by the soybean crushing industry to produce crude soy oil (also called "crude soybean oil") and soybean meal. The oil is then degummed (to remove the lecithin) and usually refined, bleached, partially hydrogenated, deodorized, and often winterized (to prevent clouding when its chilled??) to make a variety of popular products, such as salad and cooking oils, shortenings, and margarine. Soy oil also finds limited industrial use, as in paints, varnishes, and soaps. Soybean meal is used primarily as a protein source in animal feeds for the production of poultry, beef, pork, milk, butter, and eggs. A small proportion of the meal is used to make defatted soy flour, soy protein concentrates and isolates, and textured soy protein products. The idea of crushing soybeans to separate them into oil and meal is apparently a relatively recent development in the long history of soybean utilization.
Etymology . Since its first appearance in the 11th century AD, the Chinese term for "soy oil" has been written with the two characters meaning "bean" and "oil." Prior to the 1970s the Wade-Giles system romanized the standard Mandarin pronunciation of this term as tou-yu (pronounced dou-you; "bean oil") or huang tou-yu ("yellow bean oil"). Thereafter the new pinyin system romanized the term as douyou .
The Chinese term for the presscake that remains after expression of the oil from soybeans, a term which first appeared in during the 1400s, is written with the characters meaning "bean" and "cake" or "soybean" and cake." The Wade-Giles system romanized this term as tou-ping ("bean cake") or ta-tou-ping (pronounced dadou-bing ; "soybean cake"). The Chinese term for "soybean meal," prepared by the solvent extraction of soybean, a term which appeared in about 1915-20, is written with the characters meaning "bean" and "powder or flour." The Wade-Giles system romanized this as tou-fen or ta-tou-fen and the pinyin system as doufen or dadoufen .
In Japanese soy oil and soybean meal, written with similar characters. Soy oil is generally called daizu yu , but occasionally daizu no abura Soybean meal is called mame no kasu ?? In Korean, soy oil is called daedu yoo .
In the United States, the earliest terminology for soy oil followed the Chinese pattern. It was called "Chinese bean oil" by Roelofsen (1894) and "bean oil" by Carson (1909) and many other early writers well into the 1920s (Piper and Morse 1923; South Manchuria Railway Co. 1926). Other popular terms in the early 1900s were "soya bean oil" ( New York Oil, Paint and Drug Reporter 1910 Ref??; Toch 1912; New York Times 1916), "soy bean oil" (Thompson and Morgan 1912; Bailey and Reuter 1919), and "soy-bean oil" (Williams 1916a,b; Holmes 1918). The modern term "soy oil" was first used by Jordan in 1918, but it was not widely used until the 1940s. From the early 1920s until the present the term "soybean oil" (first introduced by Piper and Morse in 1923) was the one most widely used. However in 1944 Pellett of the American Soybean Association (ASA) recommended that this term be changed to the shorter "soy oil," which also avoided use of the word "bean." This change was slow to catch on, however, until the ASA began intensive market development and promotion for soy oil in the late 1970s and early 1980s, andactively stressed the benefits of the shorter term. Yet even in 1982 this oil is usually referred to in most scholarly publications and on most food product labels as "soybean oil." The term "soy oil," however, will probably become the standard eventually. Or will it be "soyoil," an even shorter term that began to appear here and there in the late 1970s (Thompson 1978; Soybean Update , 26 July 1982).
The term "soybean meal" is now the standard one used to refer to the defatted meal resulting from the solvent extraction of soybeans. But historically "soy bean meal" or "soybean meal" had at least three completely different and sometimes overlapping meanings, which caused considerable confusion. From the early 1890s into the 1920s, "soy bean meal" was used to refer to ground soybeans, i.e. whole dry soybeans that had been dry ground without heat processing to make a full-fat meal (Brooks 1893). From about 1909 until the 1920s or 1930s "soy bean meal" or "soybean meal" also referred to ground soybean cakes, i.e. after crushed soybeans were mechanically pressed to extract the oil, either the firm hydraulically pressed cakes were ground to form a loose meal (Henry 1916 (1898?? 1902??); Piper and Morse 1923) or the meal that came out of a screw press was used as is (Lindsey 1909; Williams 1916b). The term "soy bean meal" was first used in 1912 by Thompson and Morgan to refer to (European) defatted meal resulting from the solvent extraction of soybeans, but from 1924 until about 1925 was largely replaced by several closely related, longer but more precise terms containing the words "oil meal" or "oilmeal," used to clearly differentiate the defatted product from ground soybeans. These included "soy bean oilmeal" (Fairchild and Wilbur 1924), "soybean oilmeal" (Hayden and Perkins 1926), and "soybean oil meal" (Seulke 1934). The latter term continued to be used into the 1960s. By the 1950s it had been shortened to the present "soybean meal" (who first??) From the late 1970s, this term was occasionally condensed even further to "soy meal" or "soymeal" (Thompson 1978).
Paralleling this linguistic evolution was that of the present term "soybean cake," which refers to the cake resulting from crushing whole soybeans then pressing out the oil mechanically. This product was initially referred to as "bean cake" (Carson 1909; Lindsey et al. 1909) and "bean cakes" were the 61-pound, cartwheel-shaped discs produced by the traditional Chinese oil presses, such as the wedge, hand-turned screw, and early hydraulic presses. Other early terms for these cakes were "soy bean cake: (Pammel 1911; Thompson and Morgan 1912) and "soybean cake" (Henry 1916; Piper and Morse 1923). After World War II, the increasingly rare residue from hydraulic or screw presses came to be called "soybean cake."
In British English, early names for the oil were "bean-oil" (Hosie 1901) and "soyabean oil" (Sawer 1911b), which continued to be used into the 1930s (Ferree 1929; Tsao 1930a). At about that time the now standard "soya oil" started to be used. Early terms for the defatted presscake were "Chinese oilbean cake" (Senft 1872), "bean-cake" (Hosie 1901), "soya cake and soya (or soja) meal" (Gilchrist 1909), and "soya bean cake or meal" (Stockman 1916). By the 1930s?? "soya cake" and "soya meal" had become the standards.
In German, the modern term Sojaoel was the first one used (Morawski and Stingl 1887). Other early terms were Soyabohnenoel and Soyaoel (Lewkowitsch 1910) and Sojabohnenol (Matthes and Dahle 1911). Early terms for the mechanically pressed cake were Oelkuchen der Sojabohnen (Haberlandt 1878; he used the term Sojaschrot to refer to a meal made by grinding whole soybeans), Sojabohnenkuchen (Kinch 1882), and Sojakuchen or Ruckstande der Sojasamen (E. Pott 1889) or Sojapressruckstand . Early terms for solvent extracted soybean meal were Sojamehl (Hansson 1910), entfetteter Sojaschrote (Samin 1932), and Sojaextractionsschrot (Richter and Herbst 1934) or Sojaextractionsruckstand . The modern terms are Sojakuchen ?? for the mechanically pressed cake and Sojamehl ?? for the solvent extracted meal.
In French, early terms for the oil were l'huile de pois oleagineux (Montgaudry 1855; Fremy 1855), huile de Soya (Paillieux 1880, p. 448), and the modern term huile de soja (Li and Grandvoinnet 1911-12). Early terms for the cake were le tourteau ( de pois oleagineux ; Montgaudry 1855), the modern term tourteau de soja (L'Engrais 1910), and torteau de soya (Wuyts 1912). Soybean meal is ??. In Spanish, soy oil is aceite de soya and soybean meal is ??.
BASIC CONCEPTS, TERMINOLOGY, AND PROCESSES
Basic Concepts. Worldwide, some 23 oils and fats are economically important. The majority of these come from plants, in each case from the seeds of the plant, which are called oilseeds. The many oils and fats are classified into five major groups: (1) Edible vegetable oils comprised about 55% of the world's total production in 1980. Major types, in descending order of amount produced, are soy, sunflower, rapeseed, peanut, cottonseed, olive, sesame, corn, and safflower; (2) Animal fats comprise about 26% of the total. They include butter, lard (hog fat), and tallow (cattle or sheep?? fat). (3) Palm oils, comprising about 14% of the total, include coconut, palm, palm kernel, and babassu. (4) Industrial oils, comprising 3% of the total, include linseed, castor, tung, and others. (5) Marine oils, including fish, fish liver, whale, and sperm whale oils, comprise 2% of the total. Of these, the percentage of edible vegetable oils has been increasing rapidly since 1940, while the percentage of animal and marine oils has decreased sharply (Fig. ??).
Worldwide, as well as in the US, soy oil is by far the most widely used oil or fat. World soy oil production is almost three times that of second-place sunflower oil or third-place butter. Yet it is interesting to note that soybeans contain less oil than all other major oilseeds, although they are rich in protein (Fig. ??). These two important and valuable products derived from the soybean, oil and protein, are called "co-products" or "joint products." The major reliance on the meal component makes soybeans unique among oilseeds (Houck et al. 1972).
Given the soybean's low oil content, what are the major factors that have contributed to the rise of soy oil as the world's leading oil? First, its highly competitive price, which is based both on the relatively low costs of soybean and soy oil production, and on the fact that soy oil is but one of two valuable products derived from the soybean. Since about 1946, the demand for (and thus the price of) soybean meal as a protein source for livestock has increased faster than that for oil (Fig. ??). Thus, the large supply of soy oil relative to the demand has kept prices low; in effect, soy oil has almost become a by-product of the meal. Second, the reliable supply of soy oil, based on soybean crop expansion. Because soy oil is essentially a joint product (rather than a true by-product like lard or cottonseed oil) and because the soybean is a quick-yielding annual crop (rather than a slow-to-yield tree crop, as for palm oil), soybean production can respond quickly to increased demand. Third, its good nutritional value. Low in saturated fats, it contains a high percentage of "polyunsaturates" (polyunsaturated fatty acids), is rich in linoleic acid (37-53%), the one essential fatty acid necessary for good health, and, like other products derived from plants, it contains no cholesterol. Fourth, because of major advances in processing technology, soy oil is now perceived by consumers as being a high quality, light oil, with a good flavor and aroma, brightness, and clarity.
Fig. Important Oilseeds: Oil Content and Meal Protein Content
Oil Meal Protein Lb. of Oil Lb. of Meal
Oilseed Content Content per Acre per Acre
Copra (Dried coconut meat) 65-68% ...
Sesame 50-55% ...
Palmfruit 45-50% 3,475
Peanut (Groundnut) 45-50% 50-55% 705 930
Rapeseed 40-45% 35-40% 365 625
Sunflowerseed 35-45% 45-50% 525 720
Safflowerseed 30-35% 680 1,135
Olive 25-30% ...
Cottonseed 18-20% 40-45% 350
Soybean 18-20% 45-50% 285 1,255
Source: Langstraat 1976. Lb meal/acre = Erickson. 1980 p. 4.
Lb oil/acre; can't find.
And fifth, increasing and very effective soy oil marketing efforts, especially by the ASA, have helped introduce its many virtues to the public.
Soybean meal is by far the world's most widely used oilseed meal and protein concentrate in livestock and poultry feeds. Its popularity is based on its low price, its high protein quantity and quality (its amino acids are an excellent complement for those of basic feed grains), and its good availability.
Basic Terminology . An understanding of the following terms is important to an understanding of the history of soy oil:
Lipids . This general term refers to fatlike substances, including fats (such as butter or lard, which are softly solid at room temperature, 20*C or 68*F), oils (such as soy or corn soil, which are liquid at room temperature), phosphatides or phospholipids (such as lecithin, which contains phosphorus), sterols (such as cholesterol, which are fat-soluble alcohols), and waxes (which have little nutritional significance, but have higher melting point than fats.) The term "lipid," derived from the Greek lipos meaning "fat," first appeared in the English language in 1925. The term "lipoid," however, had been used since 1876.
Fatty Acids . The basic structural unit of most lipid molecules is a fatty acid. It consists of a chain of usually an even number of carbon atoms, each attached to two hydrogen atoms. At one end of the chain is a methyl group (CH3) and at the other end is an acid or carboxyl group (COOH). When each carbon atom in the chain is attached to two hydrogen atoms, the fatty acid is said to be a "saturated fatty acid." However if a pair of adjacent carbon atoms on the chain are each missing one of their hydrogen atoms, the carbon atoms satisfy the loss by forming a double bond between them. A fatty acid with one double bond and thus missing two of its full quota of hydrogen atoms is called an "unsaturated (or monounsaturated) fatty acid." A fatty acid having two or more double bonds, and thus missing four, six, or more of its full quota of hydrogen atoms, is called a "polyunsaturated fatty acid" (PUFA).
H H H H H H H H
H H H H H H
fatty acid fatty acid
The longer the carbon chain of a fatty acid, the higher the melting point and the more liquid the composition of the oil. The greater the number of double bonds (i.e. the greater the degree of unsaturation), the greater the reactivity with oxygen, which leads to rancidity. The number of double bonds and tendency to become rancid can be reduced by hydrogenation, as will be discussed later.
The fatty acids most widely found in edible oils and fats, and their abbreviations as used by oil chemists and nutritionists, are given below. The abbreviation C18:2, for example, which refers to linoleic acid, means that there are 18 carbon atoms in the basic chain and two double bonds. (Recall that double bonds are sites of unsaturation.) Note that most of the fatty acids in soy oil are composed of chains of 18 carbon atoms.
Palmitic (C16). A saturated fatty acid; abundant in palm oil.
Stearic (C18). A saturated fatty acid; small amounts precipitate out of soy oil when it is chilled, during winterization.
Oleic (C18:1). This monounsaturated fatty acid or monene, with one double bond, is found abundantly in olive oil and in lightly hydrogenated soy oil.
Linoleic (C18:2). This di-unsaturated (polyunsaturated) fatty acid or diene has two double bonds, and thus is missing four hydrogen atoms. It is the most abundant fatty acid in soy oil, comprising 37-53% of the oil. It is the only nutritionally essential fatty acid, required by the body for good health.
Linolenic (C18:3). This tri-unsaturated (polyunsaturated) fatty acid or triene has three double bonds, and thus can take on six hydrogen atoms. Considered undesirable for its tendency to promote off flavors and rancidity in soy oil, it can be reduced from 8-10% to about 3% by light hydrogenation.
Composition of Soy Oil. Unrefined soy oil, like most oils and fats, contains mostly (95-97%) triglycerides, which are glycerol esters composed of three fatty acids (not necessarily the same) attached to a glycerol molecule. It also contains a relatively large amount of phospholipids (up to 2.5%, which is separated out as lecithin), plus about 0.5% free fatty acids (they are formed when the enzyme lipase in the soybean acts on the fatty acids in the triglyceride molecule). Of the total fatty acids in unrefined soy oil, 12-15% are saturated, mostly palmitic, and 85-88% are unsaturated, of which 25-30% are oleic, 50-55% linoleic, and 5-10% linolenic.
Cis and Trans Fatty Acid Isomer. During hydrogenation many of the double bonds in soy oil, which exist originally and naturally in what is called the cis configuration, are converted to a new configuration, called trans . These forms of the same fatty acid molecule are called "isomers," since they represent different configurations of it. There are still some questions concerning the safety of trans fatty acids. A detailed discussion of trans acids, their safety, and nutritional value is given in the next chapter.
Iodine Value and Drying Character. The iodine value (IV) of an oil (formerly called the "iodine number" and determined by the amount of iodine taken up by the fatty acids under standardized conditions) is a measure of the degree of unsaturation and drying power of an oil. An oil with a high iodine value (such as linseed, whose IV is 180) is highly unsaturated and unstable; it will absorb oxygen, dry quickly to a nontacky finish, and can be used as a drying oil in paints, varnishes, and printing inks. Tung oil, made from the nuts of the Chinese tung tree, is also a good drying oil. Most drying oils owe their drying properties to the presence of a large percentage of linolenic acid (which derives its name from "linseed"), which is highly unsaturated. Linseed oil contains from 25.7-58.3% linolenic acid, while soy oil contains an average of 8-10%. Nondrying oils, such as olive, peanut, and almond oils, cannot be used in paints and varnishes. Unrefined soy oil, which has an IV of 128-135, is classified as a semi-drying oil. After its phosphatides (mainly lecithin, which inhibits drying) are removed, soy oil can be used with good results in paints and varnishes, if mixed with about three times its volume of a drying oil. A fully saturated fat would have an IV of zero.
Peroxide Value. Peroxides are formed when an oil reacts with oxygen and becomes rancid. The peroxide value of an oil is a measure of its rancidity.
The Soybean Crushing Industry. The industry which processes soybeans to release the two major commodities locked in them, soy oil and soybean meal, is called either the "soybean crushing industry" or the "soybean processing industry." For the sake of clarity, we will consistently use the former term, since there are also a number of other fairly large industries worldwide that process soybeans, including those that make tofu, soymilk, soy sauce, miso, tempeh, etc. Likewise, we will refer to a company that crushes soybeans as a "soybean crusher," avoiding the more common but, we feel, less precise term "soybean processor."
Mechanically Pressed Versus Solvent Extracted Oil. There are basically two ways of removing the oil from soybeans: pressing it out mechanically, or crushing the beans into thin flakes, then percolating these with a solvent to extract or dissolve it out. From ancient times until the early 1900s, most oil was removed by mechanical pressing. After the soybeans were ground and steamed, the oil was pressed out in primitive wooden wedge presses in East Asia, then later in hand-turned screw presses, and more recently in hydraulic presses. To move from a batch to a continuous process, the motor driven screw press or expeller was developed. Built somewhat like a large meat grinder, it heated the crushed beans by friction and pressure, and pressed out the oil through narrow slots in the metal barrel surrounding the screw. Solvent extraction systems began to replace pressing systems in the early 1900s, especially in Europe. Because soybeans have a relatively low oil content and because solvents remove a higher percentage of the oil than do mechanical pressing systems, solvent extraction came to be widely used by soybean crushers. By 1970 over 90% of the world's soy oil was solvent extracted.
Modern Soybean Crushing and Oil Refining Processes. The following is a brief description of the modern solvent extraction, degumming, and refining processes. A detailed description of each step in these processes is given later in this chapter at US History, after the 1940s.
Prior to crushing, the soybeans are cleaned, cracked, dehulled, and heat tempered, then rolled into very thin flakes. The flakes are percolated with or immersed in hexane, a liquid petroleum-based solvent, which extracts the oil by dissolving it out of the flakes. The volatile solvent is then reclaimed from the oil and from the flakes using heat and a strong vacuum, and recycled for further use. The flakes, having been "toasted" by moist heat to improve their nutritional value, and in many cases mixed with the hulls, are ground to a meal. The crude oil is degummed to remove the lecithin and typically sent to an oil refinery.
At the refinery the oil is alkali refined to remove undesirable free fatty acids, bleached with bleaching earths to remove dark pigments, often lightly hydrogenated to improve the stability, then deodorized under a vacuum to give a bland flavor and odor. Antioxidants and a defoamer may be added before bottling. Or the oil may be further processed to make salad and cooking oils, margarine, or shortening.
HISTORY OF SOYBEAN CRUSHING WORLDWIDE: OIL AND MEAL PRODUCTION AND TRADE
The history of world soybean crushing fairly closely parallels the history of world soybean production and trade (see Chapter 2), except that prior to 1910 only a small portion of the soybeans produced worldwide (i.e. in East Asia) were crushed and since 1910 Europe and Japan have been major crushers without being major soybean producers; they have imported their soybeans for crushing. A number of general periods in the history of world soy oil and meal production and trade can be identified:
AD 1000-1907 . All of the world's earliest soybean crushing took place in East Asia, primarily in Manchuria and China, using primitive stone mills. Most of the oil was used for cooking and the meal for fertilizer. Exports of meal to Japan increased after 1895. Soy oil and meal were of very minor importance, even in Asia.
1907-1939 . In about 1907 the first soybean crushing began in the West, initially in England, which quickly became the dominant crushing country in Europe. Shortly thereafter soybean crushing also began on the Continent, especially in Germany, and after 1911, in the US. Most of the oil was used in soaps and the meal in mixed livestock feeds. During World War I, the US imported huge amounts of soy oil from Japan and Manchuria, as did Europe during its postwar recovery. Starting in the late 1920s Germany's output of soy oil and meal, most of which was produced by the relatively new solvent extraction process, almost equalled that of Manchuria. But by the late 1930s production of soy oil and meal in both Manchuria and Germany was plummeting. Between 1936 and 1942, the US passed both these countries to become the world's leading soybean crusher, a lead that has never been relinquished. In 1934, when soy oil was at its pre-World War II peak, it constituted only 11.6% of the world's production of vegetable oils (Horvath 1936).
1940-1949 . During the 1940s, with Manchuria and Europe being ravaged by the war, the US greatly increased its lead as the world's major soybean crushing country. The four keys to this growth were: (1) a large and rapidly growing domestic soybean crop (Europe always had to rely on imports), (2) a large and rapidly growing domestic demand for soy oil and meal (which Manchuria never had), (3) an advanced technological based in oilseed processing and utilization (which Manchuria never had), and (4) a strong economy free of fighting on its own land. World War II, in fact, stimulated the US crushing industry, with strong demand for soy oil from Europe. During the 1940s and 1950s major advances were made in soy oil refining, which greatly increased its acceptability in cooking and salad oils, margarine, and shortening. Also during the 1940s, for the first time in history, the majority of the world's soybeans were crushed to yield oil and meal.
1950-1982 . Starting in about 1946 and increasing thereafter, the demand for soybean meal increased faster than the demand for soy oil, as the West dramatically increased its consumption of meat, poultry, and dairy products. This trend kept soy oil prices low, which further encouraged oil consumption. After the mid-1950s exports of soy oil and meal increased dramatically, as the US became the world's top supplier of these two products. In 1966 soy oil passed butter to become the world's leading edible oil or fat. Between 1960 and 1982, world production of soy oil skyrocketed (Fig. ??). In 1982 palm oil was in second place worldwide, sunflower seed oil in third, butter (fat content) in fourth, and rapeseed (canola) oil in fifth, all far behind soy oil.
Soybean meal was even further out in front of its nearest competitor, cottonseed meal, followed by fish meal, sunflower seed meal, rapeseed meal, and peanut meal (Fig. ??). In 1982 soybean meal supplied 67.5% of the protein from the world's oilseed protein meals, the main source of protein in livestock feeds. The next largest meal, cottonseed meal, supplied a mere 7.5% of the total protein (USDA Foreign Agricultural Service 1982). A rapid rise in meat (primarily chicken) consumption among the middle and upper classes in Third World countries during the 1970s, a major change in eating habits, had helped fuel this boom (Crittendon 1981).
Between 1955 (when the first statistics on world production began to be kept) and 1981, world production of all oils and fats (edible and industrial) increased from 25.5 million tonnes (metric tons) to 59.2 million tonnes (up 132%), and per capita production during that period increased from about 7.03 kilograms to 13.1 kg (up 86.3%). Soy oil production during that period increased from 2.1 million tonnes to 13.6 million tonnes (up 548%) and per capita production increased from 0.758 kg-3.03 kg (up 300%). During this period soy oil production as a percentage of total world oil and fat production, increased from 9.2% in 1955 to 22.5%, a truly dramatic increase (Fig. ??). Moreover, in 1981, soy oil accounted for about 44% of the world's edible vegetable oils (35% if palm oils are included). At that time, more than 95% of the world's soy oil was used in human foods.
During the 1970s Brazil emerged as a major soybean crusher, challenging the US lead. By 1982 Brazil was crushing 14 million tonnes of soybeans annually, almost half of America's 29.3 million. Other leading soybean crushing nations in 1982 were the 10 European Economic Community Nations (taken as a bloc; 11.2 million tonnes. Capacities of major member countries in million tonnes were West Germany 4.3, France 3.5, Netherlands 3.0), China 4.1 million tonnes, Japan 3.6 million tonnes, Spain 3.3 million tonnes, and Mexico 1.75 million tonnes.