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Soybean Oil

Production

In processing soybeans for oil extraction and subsequent soy flour production, selection of high quality, sound, clean, dehulled yellow soybeans is very important. Soybeans having a dark colored seed coat, or even beans with a dark hilum will inadvertently leave dark specks in the flour, are undesirable for use in commercial food products. All commercial soybeans in the United States are yellow or yellow brown.

To produce soybean oil, the soybeans are cracked, adjusted for moisture content, rolled into flakes and solvent-extracted with commercial hexane. The oil is then refined, blended for different applications, and sometimes hydrogenated. Soybean oils, both liquid and partially hydrogenated, are exported abroad, sold as "vegetable oil," or end up in a wide variety of processed foods. The remaining soybean husks are used mainly as animal feed.

The major unsaturated fatty acids in soybean oil triglycerides are 7% linolenic acid (C18:3); 51% linoleic acid (C-18:2); and 23% oleic acid(C-18:1). It also contains the saturated fatty acids 4% stearic acid and 10% palmitic acid.

Soybean oil has a relatively high proportion, 7–10%, of oxidation prone linolenic acid, which is an undesirable property for continuous service, such as in a restaurant. In the early nineties, Iowa State University developed soybean oil with 1% linolenic acid in the oil. Three companies, Monsanto, DuPont/Bunge, and Asoyia in 2004 introduced low linolenic, (C18:3; cis-9, cis-12, cis-15 octadecatrienoic acid) Roundup Ready soybeans. In the past hydrogenation was used to reduce the unsaturation in linolenic acid, but this produced the unnatural trans-fatty acid trans fat configuration, whereas in nature the configuration is cis. This external picture from North Dakota State University compares soybean oil fatty acid content with other oils.
 

Fats and oils substances derived from soy that are composed of triglycerides. Nominally, oils are liquid at room temperature, and fats are solid; a dense brittle fat is a wax. Although many different parts of plants may yield oil, [1] in actual commercial practice oil is extracted primarily from the seeds of soybean plants.
The temperature-based distinction between oils and fats is imprecise, since definitions of room temperature vary, and typically any one substance has a melting range instead of a single melting point.
Triglyceride vegetable fats and oils include not only edible, but also inedible vegetable fats and oils, used in lubricants, paints, cosmetics, pharmaceuticals, and other industrial purposes. Although thought of as esters of glycerin and a varying blend of fatty acids, in fact these oils contain free fatty acids and diglycerides as well.

Uses

Some soy oils are consumed directly, or used directly as ingredients in food - a role that they share with some animal fats. The oils serve a number of purposes in this role:

· Texture - oils can serve to make other ingredients stick together less.
· Flavor - less-flavorful oils command premium prices.
· Flavor base - oil can also "carry" flavors of other ingredients, since many flavors are present in chemicals that are soluble in oil.

Secondly, soybean oil can be heated, and used to cook other foods, soybean oils that are suitable for this purpose must have a high flash point.

Hydrogenated oils

Triglyceride-based vegetable fats and oils can be transformed through partial or complete hydrogenation into fats and oils of higher melting point. The hydrogenation process involves "sparging" the oil at high temperature and pressure with hydrogen in the presence of a catalyst, typically a powdered nickel compound. As each double-bond in the triglyceride is broken, two hydrogen atoms form single bonds. The elimination of double-bonds by adding hydrogen atoms is called saturation; as the degree of saturation increases, the oil progresses towards being fully hydrogenated. An oil may be hydrogenated to increase resistance to rancidity (oxidation) or to change its physical characteristics. As the degree of saturation increases, the oil's viscosity and melting point increase. The use of hydrogenated oils in foods has never been completely satisfactory. Because the center arm of the triglyceride is shielded somewhat by the end triglycerides, most of the hydrogenation occurs on the end triglycerides. This makes the resulting fat more brittle. A margarine made from naturally more saturated tropical oils will be more plastic (more "spreadable") than a margarine made from hydrogenated soy oil. In addition, partial hydrogenation results in the formation of trans fats, which have increasingly been viewed as unhealthy since the 1970s. (In the U.S., the USDA Standard of Identity for a product labeled as vegetable oil margarine specifies that only canola, safflower, sunflower, corn, soybean, or peanut oil may be used.[7] Products not labeled vegetable oil margarine do not have that restriction.)

Industrial uses

Soy oils are used as an ingredient or component in many manufactured products such as soaps, skin products, candles, perfumes and other personal care and cosmetic products. Soybean oil is naturally clearer than petroleum distillates and other vegetable oils, making it easier to obtain brightly colored ink. Recent studies involving engineering of certain oils in the bean have resulted in even clearer oils.

Soybean oil has also been found effective as an insect repellent in some studies.[23] [24] The commercial product Bite Blocker contains soybean oil as one active ingredient.

· Some oils are particularly suitable as drying agents, and are used in making paints and other wood treatment products.

· Vegetable oil is being used to produce bio-degradable hydraulic fluid[8]and lubricant.[9]

Soy oil has been chemically modified to contain hydroxyl groups, are becoming increasingly important in the production of polyurethane plastic for many applications. These modified vegetable oils are known as natural oil polyols.

After testing over 2,000 different vegetable oil formulations, researchers for the NAA came up with the solution of using soybean oil. In 1987, soybeans were tested by The Gazette from Iowa in a practical printing run. The test was successful, and soy ink became increasingly popular. Now it has come to be used in over 95% of America’s daily newspapers that circulate more than fifteen hundred copies per run. In addition, about one quarter of commercial printers in the United States operate using soy ink.

To make soy ink, soybean oil is slightly refined and then blended with pigment, resins, and waxes. Even though soybean oil is an edible vegetable oil, soy ink is not edible or 100% biodegradable because the pigments and other additives that are mixed with the oil are the same as those used in petroleum-based inks. They are, however, overwhelmingly more environmentally friendly.

Pet food additive

Soy oil is used in production of some pet foods. AAFCO defines vegetable oil, in this context, as the product of vegetable origin obtained by extracting the oil from seeds or fruits which are processed for edible purposes. In some poorer grade pet foods, the oil is listed only as "vegetable oil", without specifying the particular oil. [10]
Soybean oil used as fuel
Soybean oils are also used to make biodiesel, which can be used like conventional diesel. Some vegetable oil blends are used in unmodified vehicles but straight vegetable oil, also known as pure plant oil, needs specially prepared vehicles which have a method of heating the oil to reduce its viscosity. The soybean oil economy is growing and the availability of biodiesel around the world is increasing.

Extraction

The "modern" way of processing soy oil is by chemical extraction, using solvent extracts, which produces higher yields and is quicker and less expensive. The most common solvent is petroleum-derived hexane.

Another way is physical extraction, which does not use solvent extracts. It is made the "traditional" way using several different types of mechanical extraction.[11] This method is typically used to produce the more traditional oils , and it is preferred by most "health-food" customers in the USA and in Europe. Expeller-pressed extraction is one type, and there are two other types that are both oil presses: the screw press and the ram press. Oil seed presses are commonly used in developing countries, among people for whom other extraction methods would be prohibitively expensive. [12] Supercritical carbon dioxide can also be used for the extraction purpose and is non toxic.[15]

Production

Crude oil, straight from the crushing operation, is not considered edible in the case of most oilseeds. The same is true for the remaining meal. For instance, animals fed raw soy meal will waste away, even though soy meal is high in protein. Researchers at Central Soya discovered that a trypsin inhibitor in soybeans could be deactivated by toasting the meal, and both licensed their invention, and sold soy meal augmented with vitamins and minerals as MasterMix, a product for farmers to mix with their own grain to produce a high quality feed.

The processing of soy oil is typical of that used with most vegetable oils. Crude soy oil is first mixed with caustic soda. Saponification turns free fatty acids into soap. The soap is removed with a centrifuge. Neutralized dry soap stock (NDSS) is typically used in animal feed, more to get rid of it than because it is particularly nourishing. The remaining oil is deodorized by heating under a near-perfect vacuum and sparged with water. The condensate is further processed to become vitamin E food supplement, while the oil can be sold to manufacturers and consumers at this point.
Some of the oil is further processed. By carefully filtering the oil at near-freezing temperatures, "winter oil" is produced. This oil is sold to manufacturers of salad dressings, so that the dressings do not turn cloudy when refrigerated.

The oil may be partially hydrogenated to produce various ingredient oils. Lightly hydrogenated oils have very similar physical characteristics to regular soy oil, but are more resistant to becoming rancid.

Margarine oils need to be mostly solid at 32 °C (90 °F) so that the margarine does not melt in warm rooms, yet it needs to be completely liquid at 37 °C (98 °F), so that it doesn't leave a "lardy" taste in the mouth.

Another major use of soy oil is for fry oils. These oils require substantial hydrogenation to keep the polyunsaturates of soy oil from becoming rancid.

Hardening soy oil is done by raising a blend of vegetable oil and a catalyst in near-vacuum to very high temperatures, and introducing hydrogen. This causes the carbon atoms of the oil to break double-bonds with other carbons, each carbon forming a new single-bond with a hydrogen atom. Adding these hydrogen atoms to the oil makes it more solid, raises the smoke point, and makes the oil more stable.

Hydrogenated soy oil differ in two major ways from other oils which are equally saturated. During hydrogenation, it is easier for hydrogen to come into contact with the fatty acids on the end of the triglyceride, and less easy for them to come into contact with the center fatty acid. This makes the resulting fat more brittle than a tropical oil; soy margarines are less "spreadable". The other difference is that trans fatty acids (often called trans fat) are formed in the hydrogenation reactor, and may amount to as much as 40 percent by weight of a partially hydrogenated oil. Trans acids are increasingly thought to be unhealthy.

Sparging

In the processing of edible oil, the oil is heated under vacuum to near the smoke point, and water is introduced at the bottom of the oil. The water immediately is converted to steam, which bubbles through the oil, carrying with it any chemicals which are water-soluble. The steam sparging removes impurities that can impart unwanted flavors and odors to the oil.

Comparison oils

In the 2002–2003 growing season, 30.6 million metric tons of soybean oil were produced worldwide, constituting about half of worldwide edible vegetable oil production, and thirty percent of all fats and oils produced, including animal fats and oils derived from tropical plants.[22]

The following triglyceride vegetable oils account for almost all world-wide production, by volume. All are used as both cooking oils and as SVO or to make biodiesel. According to the USDA, the total world consumption of major vegetable oils in 2000 was:

Other significant triglyceride oils include:
· Corn oil, one of the most common, and inexpensive cooking oils.
· Hazelnut and other nut oils
· Linseed oil, from flax seeds
· Rice bran oil, from rice grains
· Safflower oil, a flavorless and colorless cooking oil.
· Sesame oil, used as a cooking oil, and as a massage oil, particularly in India.

History of edible vegetable oils in North America

Soybeans were an exciting new crop from China in the 1930s. Soy was protein-rich, and the light tasteless oil was extremely high in polyunsaturates. Henry Ford established a soybean research laboratory, developed soybean plastics and a soy-based synthetic wool, and built a car almost entirely out of soybeans.[16] Roger Drackett had a successful new product with Windex, but he invested heavily in soybean research, seeing it as a smart investment.[17] By the 1950s and 1960s, soybean oil had become the most popular vegetable oil in the US.

Waste oil

As of 2000, the United States were producing in excess of 11 billion liters of waste vegetable oil annually, mainly from industrial deep fryers in potato processing plants, snack food factories and fast food restaurants.

Waste vegetable oil, sold as the commodity yellow grease has a market value of approximately $1.09 per US gallon ($0.29/l or $335 per metric tonne), expected to rise to $1.21 by 2013, enough to make collection economically viable.[19]

Currently, the largest uses of waste vegetable oil in the U.S. are for animal feed, pet food, and cosmetics. Since 2002, an increasing number of European Union countries have prohibited the inclusion of waste vegetable oil from catering in animal feed. Waste cooking oils from food manufacturing, however, as well as fresh or unused cooking oil, continues to be used in animal feed. [20]


1.  Compare, for example, the list of raw materials from which essential oils are extracted.
2.  4,000-year-old 'kitchen' unearthed in Indiana. Retrieved on 2006-07-31.
3.  External blockade...by polyunsaturated fatty acids. pubmed. Retrieved on 2007-01-18. - see page 1 of this link
4.  Antiarrythmic effects of omega-3 fatty acids. pubmed. Retrieved on 2007-01-18.
5.  Alpha-linolenic acid, cardiovascular disease and sudden death. pubmed. Retrieved on 2007-01-18.
6.  Omega-3 and health. pubmed. Retrieved on 2007-01-18.
7.  USDA Standard of Identity.
8.  Linda McGraw (April 19, 2000). Biodegradable Hydraulic Fluid Nears Market. USDA. Retrieved on 2006-09-29.
9.  Cass Scenic Railroad, West Virginia. GWWCA. Retrieved on 2007-07-03.
10.  Ingredients to avoid. The Dog Food Project. Retrieved on 2007-06-26.
11.  Kalu (oil presser). Banglapedia. Retrieved on 2006-11-12.
12.  Janet Bachmann. Oilseed Processing for Small-Scale Producers. Retrieved on 2006-07-31.
13.  B.L. Axtell from research by R.M. Fairman (1992). Illipe. Minor oil crops. FAO. Retrieved on 2006-11-12.
14.  Ghani. Banglapedia. Retrieved on 2006-11-12. A ghani is a traditional Indian oil press, driven by a horse or ox.
15.  M. Eisenmenger, N. Dunford, F. Eller and S. Taylor (2005). "Pilot Scale Supercritical Carbon Dioxide Extraction and Characterization of Wheat Germ Oil". AOCS Proceedings 96.
16.  Soybean Car. Popular Research Topics. Benson Ford Research Center. Retrieved on 2006-10-23.
17.  Barry M. Horstman. "Philip W. Drackett: Earned profits, plaudits", Cincinnati Post, May 21, 1999. Retrieved on 2006-10-22. 
18.  Canola oil. Retrieved on 2006-07-31.
19.  Anthony Radich. Biodiesel Performance, Costs, and Use (PDF). Retrieved on 2006-07-31.
20.  Waste cooking oil from catering premises. Retrieved on 2006-07-31.

22.  United States Department of Agriculture, Agricultural Statistics 2004. Table 3-51.
23.  Barnard, D.R. and R. Xue. 2004. Laboratory evaluation of mosquito repellents against Aedes albopictus, Culex nigripalpus, and Ochlerotatus triseriatus (Diptera: Culicidae). J. Med. Entomol. 41(4):726-730.
24.  Fradin, M.S. and J.F. Day. 2002. Comparative efficacy of insect repellents against mosquito bites. N. Engl. J. Med. 347:13-18.

· Beare-Rogers, J.L. 1983. "Trans and positional isomers of common fatty acids." In H.H. Draper (ed.) Advances in Nutritional Research. Vol. 5 Plenum Press, New York, pp. 171-200.
· Berry, E.M. and Hirsch, J. 1986. "Does dietary linolenic acid influence blood pressure?" American Journal of Clinical Nutrition. 44: 336-340.
· Beyers, E.C. and Emken, E.A. 1991. "Metabolites of cis, trans, and trans, cis isomers of linoleic acid in mice and incorporation into tissue lipids." Biochimica et Biophysica Acta. 1082: 275-284.
· Birch, D.G., Birch, E.E., Hoffman, D.R., and Uauy, R.D. 1992. "Retinal development in very-low-birth-weight infants fed diets differing in omega-3 fatty acids." Investigative Ophthalmology and Visual Science 33(8): 2365-2376.
· Birch, E.E., Birch, D.G., Hoffman, D.R., and Uauy, R. 1992. "Dietary essential fatty acid supply and visual acuity development." Investigative Ophthalmology and Visual Science. 33(11): 3242-3253.
· Brenner, R.R. 1989. Factors influencing fatty acid chain elongation and desaturation, in the role of fats in human nutrition. 2nd edn. (eds A.J. Vergroesen and M. Crawford), Academic Press, London pp. 45-79.
· British Nutrition Foundation. 1987. Report of the task force on trans fatty acids. London: British Nutrition Foundation.
· Central Soya annual report, 1979.
· Emken, E. A. 1984. "Nutrition and biochemistry of trans and positional fatty acid isomers in hydrogenated oils." Annual Reviews of Nutrition. 4: 339-376.
· Enig, M.G., Atal, S., Keeney, M and Sampugna, J. 1990. "Isomeric trans fatty acids in the U.S. diet." Journal of the American College of Nutrition. 9: 471-486.
· Ascherio, A., Hennekens, C.H., Baring, J.E., Master, C., Stampfer, M.J. and Willett, W.C. 1994. "Trans fatty acids intake and risk of myocardial infarction." Circulation. 89: 94-101.
· Gurr, M.I. 1983. "Trans fatty acids: Metabolic and nutritional significance." Bulletin of the International Dairy Federation. Document 166: 5-18.
· Hui Y. H., editor, "Bailey's Industrial Oil and Fat Products," Edible Oil and Fat Products
· Koletzko, B. 1992. "Trans fatty acids may impair biosynthesis of long-chain polyunsaturates and growth in man." Acta Paediatrica. 81: 302-306.
· Lief, Alfred, It floats: The story of Procter & Gamble, published 1958 by Rinehart.
· MacMillen, Harold W., Mr. Mac and Central Soya: the foodpower story, published 1967 by Newcomen Society
· Marchand, C.M. 1982. "Positional isomers of trans-octadecenoic acids in margarine." Canadian Institute of Food Science and Technology Journal. 15: 196-199.
· Mensink, R.P., Zock, P.L., Katan, M.B. and Hornstra, G. 1992. "Effect of dietary cis-and trans-fatty acids on serum lipoprotein[a] levels in humans." Journal of Lipid Research. 33: 1493-1501.
· Siguel, E.N. and Lerman, R.H. 1993. "Trans fatty acid patterns in patients with angiographically documented coronary artery disease." American Journal of Cardiology. 71: 916-920.
· Troisi, R., Willett, W.C. and Weiss, S.T. 1992. "Trans-fatty acid intake in relation to serum lipid concentrations in adult men." American Journal of Clinical Nutrition. 56: 1019-1024.
· Willett, W.C., Stampfer, M.J., Manson, J.E., Colditz, G.A., Speizer, F.E., Rosner, B.A., Sampson, L.A. and Hennekens, C.H. 1993. "Intake of trans fatty acids and risk of coronary heart disease among women." The Lancet. 341: 581-585.
 

• Hydro Safe Biodegradable Oil. Hydrosafe.
• Hyfoma. Retrieved on 2006-11-05.
• Oil yields and characteristics. Journey to forever. Retrieved on 2006-11-05.
• Oil Crops. National Non Food Crops Centre. Retrieved on 2006-11-05. Information on the use of vegetable oils in fuel, lubricants, polymers, solvents and surfactants.

Retrieved from "http://en.wikipedia.org/wiki/Vegetable_fats_and_oils"