Extraction soybeans

Solvent Extraction. Extraction processes, used for separating one substance from another, are commonly employed in the pharmaceutical and food processing industries. Oilseed extraction is the most widely used extraction process on the basis of tons processed. Extraction-grade hexane is the solvent used to extract soybeans, cottonseed, com, peanuts, and other oilseeds to produce edible oils and meal used for animal feed supplements. Tight specifications require a narrow distillation range to minimize solvent losses as well as an extremely low benzene content. The specification also has a composition requirement, which is very unusual for a hydrocarbon, where the different components of the solvent must be present within certain ranges (see Exthaction). 

In many cases, the product is toxic as in the case of the conjugate of trichloroethylene, which is thought to be responsible for the aplastic anemia induced in calves fed trichloroethylene-extracted soybean oil meal (27). The unstable product shown in brackets (Fig. 7.20) has the potential to lose HC1 to form a reactive thioketene or tautomerize to form the reactive chlorothioacetyl chloride (27). 

Analysis of Volatile Compounds From Supercritical Extracted Soybeans by Headspace Gas Chromatography and Thermal Desorption of a Polymer Adsorbent (Snyder and King, 1994)... 

No chemically extracted feeds (such as solvent-extracted soybean meal). 

Bell, J.M., Tyler, R.T. and Rakow, G. (1998) Nutritional composition and digestibility by 80-kg to 100-kg pigs of prepress solvent-extracted meals from low glucosi-nolate Brassica juncea, B. napus and B. rapa seed and of solvent-extracted soybean meal. Canadian Journal of Animal Science 78, 199-203. 

Starch Meat extract Peptone Glucose Yeast extract Soybean meal... 

Soybeans owe their dominance of the oilseed market to the value of their protein, which is much greater than that of other oilseeds. Of the oilseed meals produced in 2003, 129.58 million MT out of a total of 185.69 milllion MT was soybean meal (1). Of the money made on extracting soybeans, the meal accounted for between 51% and 76% of the total in the last 10 years. Soybean oil of typical composition performs well as a salad oil, but it is usually hydrogenated for use as a margarine stock or frying oil. Soybean oil s stability to oxidation also is limited by its content... 

Figure 3. Process flow diagram for direct solvent-extracting soybeans.

Figure 4. Depiction of equipment and process flow diagram for direct solvent-extracting soybeans (courtesy of French Oil Mill Machinery Co., Piqua, OH).

Quality standards and trading rules for solvent-extracted soybean meal and oil are designated by the National Oilseed Processors Association and are available at a website (145). Soybean products are remarkably uniform in their quality characteristics compared with alternative sources of oil and meal. 

Lecithin recovered from solvent-extracted soybean oil had different phospholipid class compositions from those produced by mechanical pressing (198). The percentage of phosphatidylcholine was considerably higher in lecithin recovered from extruded-expelled oU than from solvent-extracted oil. The phosphatidylcholine- and phosphatidylinositol-enriched fractions produced by ethanol extraction of the crude lecithin also showed different functional properties (199). 

Extruders are also used for extrusion of secondary resources (coproducts rendering). Poultry mortalities, eggshells, feathers, shrimp heads, and various other meat and fisheries coproducts have been mixed with solvent-extracted soybean meal and extruded at sterilization temperatures for use as animal feeds. Significant amounts of fats can be recycled in this manner, while fresh and near the site of production (92). 

A small-scale chain conveyor type of extractor was developed in the 1940s at Iowa State University with the intent of using trichloroethylene solvent to extract soybeans. Crown Iron Works of Minneapolis, Minnesota, licensed the technology and extractor design, and supplied several continuous solvent extraction plants in 1951 using the new extractor and trichloroethylene solvent (6). The meal from these plants proved detrimental to animals, so the plants were either closed or converted to petroleum-based solvents (7). The chain-type extractor apparatus continued on and is the basis of the modern Crown Iron Works Model III extractor used today. 

TABLE 5. Residual Oil Contents of Extracted Soybean Meals. 

Socha and Satter (28) conducted a study to determine the production response of early lactation cows fed either solvent-extracted soybean meal, raw soybeans, extruded whole soybeans, or roasted soybeans with alfalfa silage as the sole forage source. They reported that dry matter intakes were lower for cows on the raw and roasted soybean treatments. Cows on the extruded soybean diet produced more milk, milk protein, and more 3.5% fat-corrected milk than cows fed the other diets. Body weight changes and body condition scores did not differ among the various treatments. 

At 24 MPa, the calculated amount extracted was 54.4% of the available lipid versus 45% for the experimental amount. At 31 MPa, the values were 58% and 42%. Lee et al. (7) indicated that 57% of the total lipid composition in Skeletonema costatum consisted of acyl glycerols. The calculated yields of 58% and 54% in the present study indicated that almost all of the nonpolar lipids were extracted by CO,. Friedrich et al. (14) claimed that no significant difference was observed in the quantity of total saponiflables between SC CO2 and hexane extracted soybean oils. This is in agreement with the results for SC CO2 extracted and solvent extracted oils of Skeletonema. 

Eldridge, A.C., Kalbrener, J.E., Moser, H.A., Honig, D.H., Rackis, J. J., and Wolf, W.J. 1971. Laboratory evaluation of hexane alcohol azeotrope-extracted soybean flakes as a source for bland protein isolates. Cereal Chem. 48 644-646. 

Mechanically pressed soybean oil Solvent extracted soybean oil Solvent extracted wheat germ oil... 

Soybean proteins are widely used as food additives in European derived societies, primarily in processed foods, and this trend continues to grow annually. This makes soybean proteins a pervasive component of the human diet in industrialized countries. Solvent extracted soybean meal is also widely used as an animal feed additive (ref. 5, for review), because it is an inexpensive source of high quality protein that contains more of essential amino acids lysine and tryptophan than most cereal crops. Combined with corn, the other primary feed grain used in the United States, a ration can be assembled that is adequate in both sulfur amino acid and lysine contents, and provides a high protein diet that is well balanced for poultry and pigs. 

Arnica Oil CLR. [Hei l/Cospha] Arnica extract, soybean oil, tocoi ierol emollient, condititmer protective skin and hair care prods. 

Protease Production Profile in Different Substrates by Solid-State Fermentation Mediums containing 10 g of soybean extract (soybean milk), soybean flour, milk powder, rice, and... 

The solubility of soybean extract, soybean flour, and milk powder had a positive influence on the results from SmF. For milk powder, the higher amount of water decreased the damaging effects of sterilization, especially regarding the texture, increasing enzyme production. 

Tocopherol Mechanically Pressed Soybean Oil Solvent-extracted Soybean Oil Solvent-extracted Wheat Germ Oil... 

For simplicity, solvent extracting soybeans, or for that matter any oilseed, has been likened to cleaning paint from a brush. To get the brush clean, the solvent must have good contact and penetration into the brush s bristles, sufficient heat to quickly do the cleaning, and enough clean solvent and time to remove all the paint. 

Soybeans are an important source of edible oil, but many have argued that soybean is actually a protein crop because 60-70% of the returns in processing soybeans is due to the sale of meal (Table 11.1). No other oilseed contains as much protein. Thus, processes used to extract soybean oil are designed to maximize meal quality for use in livestock feeds. 

Fig. 11.4. Flow diagram for direct soivent extracting soybeans.

Fig. 11.6. Aerial (A) and interior (B) photographs of direct-solvent-extraction soybean plants (aerial photograph provided by Bunge Corporation, St. Louis, MO interior photograph provided by Crown Iron Works, Minneapolis, MN).

Only when soybeans are processed in plants designed for other oilseeds (e.g., cottonseed, sunflower seed, etc.), which must be prepressed, are soybeans subjected to prepress solvent extraction. Soybeans do not contain sufficient oil to require or justify prepressing and are rarely, if ever, prepress solvent extracted. In prepress solvent extraction, part of the oil, that which is easily removed, is pressed out, generally as de-... 

The best quality oil, low in phosphatides, free fatty acids, nonsaponifiable matter and pigments, is extracted first, while poorer quality lipids are extracted with more exhaustive extraction. The industry, however, strives for the most complete extraction possible. Residual oil contents of finished solvent-extracted soybean meal range 0.5-1.5% (toasting defatted soybean meal liberates oil, and toasted meal will test higher in oil content than do drained untoasted extracted flakes). Some have advocated doing less complete oil extraction to reduce refining costs, but not ail extraction plants have capabilities to alkali refine and, thus, there is little incentive to extraction plants to minimize refining loss. 

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