Effect of temperature and screw speed on stability of fumonisin B1 in extrusion-cooked corn grits

Corn grits spiked with fumonisin B(1) (FB(1)) at a level of 5 mu g/g were extrusion cooked in a corotating twin-screw extruder at different temperatures (140, 160, 180, and 200 degrees C) and screw speeds (40, 80, 120, and 160 rpm). Good recoveries of FB(1) were obtained from the nonextruded as well as the extruded grits by using high-performance liquid chromatography. Both the barrel temperature and the screw speed significantly (P less than or equal to 0.05) affected the extent of fumonisin reduction in extruded grits. As expected, the FB(1) recovered decreased with an increase in temperature and a decrease in screw speed. The amount of FB(1) lost from cooking grits at the different extrusion parameters used in this study ranged from 34 to 95%. About 46-76% of the spiked FB(1) was lost when the grits were cooked at temperatures and screw speeds that resulted in acceptable product expansion and color.