Modern processing plants extract soyabean oil by solvent liquid transfer. Soyabeans are cleaned, cracked, dehulled and conditioned into a thin flake before they enter the extractor. Extraction is by successive, countercurrent washes of hexane solvent. The extracted flakes are then carried by a sealed conveyor to be desolventized in enclosed vessels by application of jacket and sparge steam. Hexane is removed from the oil in rising film evaporators and with final vacuum distillation. Hexane is recovered from the meal and the oil in atmospheric condensers. The complete plant installation is explosion-proof and all equipment is sealed and vapor-proof. For a good operation, soyabeans must be clean, undamaged and at the correct moisture and temperature. Parameters of the process in the plant are: tonnage, hexane loss and energy usage. Oil quality is measured in terms of free fatty acids, absence of residual hexane and crude oil color. Meal quality is determined by residual oil, moisture, protein, urease activity protein solubility and mesh size in the finished product. Innovations at modern plants include degumming of the oil, lecithin drying and blending and production of soyabean meal with high protein solubility for human consumption.
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Serrato, A.G. Extraction of oil from soybeans. J Am Oil Chem Soc 58, 157–159 (1981). https://doi.org/10.1007/BF02582327
- Soybean Flake
- Solvent Extraction Plant
- Hexane Vapor
- American Soybean Association
- Sparge Steam