Abstract: A device for inactivating enzymes in soybeans comprises a generally air tight pressure cylinder having an axial screw which moves the soybeans from an upstream end to a downstream end where the inactivated soybeans are discharged. The screw has three zones, an upstream feed zone, a central agitation zone which runs about 1/2 the length of the pressure cylinder, and a downstream feed zone. A steam jacket is placed over the pressure cylinder especially in the area starting with the beginning of the agitation zone, and also an infeed pipe for the feeding therein of a buffer solution.