Conditioning of oil‐bearing materials for solvent extraction by extrusion

Abstract

AbstractA new procedure, based on extrusion, was developed to prepare soybeans for direct solvent extraction. The procedure eliminates the need of controlled cracking, partial shell remotion, heating and flaking, requiring only an adequate communition to particles passing Sieve USS 14 followed by extrusion in a specially developed extruder. Extruded soybeans were obtained in the form of hard and porous agglomerates, without any dusting tendency, higher extraction, draining and percolation rates, lower solvent hold up and higher apparent density than the best possible flakes. Extruded soybeans were processed by solvent extraction in batch and continuous industrial installations, enabling substantial increases in capacity (up to 100%) and reduction in overall steam consumption (up to 30%) when compared with flakes processing. Extracted oil from extruded soybeans seems to show lower levels of gums and toasted meal at higher soluble protein levels for the same urease activity. Peanut press‐cakes were preconditioned by extrusion before solvent extraction in batch‐type installations, enabling a substantial reduction in residual oil for similar conditions with nonextruded press‐cake. For existing plants, the new procedure allows a substantial increase in plant capacity and lower steam consumption. For new plants, the new procedure allows substantial capital savings in equipment and space. The new procedure enables soybean processing by direct solvent extraction in small batch‐type installation, which may be very convenient for some underdeveloped areas.