Effect of free fatty acids addition on corn grits extrusion cooking

The influence of added fatty acids on extrusion cooking of corn grits and e xtrudate properties was studied. Samples with three average corn grits part icle sizes were processed in a twin-screw extruder; fatty acids content (0. 2-0.8%, wb) varied, and experimental conditions were kept constant (moistur e content 18.4% wb, barrel temperature 150 degrees C, screw speed 165 rpm). The effect of adding fatty acids was studied by analyzing water solubility and absorption indices, expansion indices, and mechanical (puncture test) and structural (computerized image analysis) extrudate properties. When fat ty acids were added, water solubility and absorption indices decreased, rad ial expansion index decreased, longitudinal expansion index increased, numb er of cells increased, and mechanical resistance of extrudates decreased. T he influence of added fatty acids was attributed to the formation of fatty acids-amylose complexes.