an agitator for use on an agitator shaft having an axis of rotation . the agitator has a blade mount configured and dimensioned to receive the agitator shaft and being further configured and dimensioned so as to hold a plurality of agitator blades radially with respect to the axis of rotation . each agitator blade has a plurality of segments , including an upper segment relative to the axis of rotation and a lower segment relative to the axis of rotation . the segments are inclined at an acute angle relative to the axis of rotation in the direction of rotation , wherein the acute angle changes continuously or stepwise from about 25 ° at the upper segment to about 65 ° at the lower segment .