Characterization of Partially Defatted Peanut Flour Using Dry Extruder and Screw Pressing

This study investigated oil removal from peanuts using dry, wet extrusion and screw pressing. Dry extrusion removed about 50% of the original oil in the peanuts and extrudates were pressed immediately after extrusion using a continuous screw press with a horizontal bar cage. About 66% of the residual oil present in the extrudates was removed, resulting in 8% oil, 47% protein and 6% moisture in the press cakes. Heat treatment during extrusion and pressing reduced the protein dispersibility index (PDI) in the raw peanuts from 88 to 69%, and 66% in the extrudates and press cakes, respectively. The trypsin inhibitor was quite stable in its reaction with the heat treatment; 23 and 26% of the trypsin inhibitor activity was destroyed only by the dry extrusion and the screw press, respectively.