The effects of feed rare (10-20 kg/h) and screw speed (100-300 rpm) on the residence rime distribution (RTD) were studied in the extension of tarhana in a twin-screw extruder. The Peclet number (Pe) was used to determine the extent of axial mixing in the extruder. Increasing tile screw speed or feed rate reduced tile mean residence time (t(m)). Feed rate had more effect on t(m) than screw speed. The value of Pe varied from 1.1 to 8.7. The pow in die extruder approached plug flow as the feed I-are was increased or the screw speed was decreased.