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Effect of Free Fatty Acids Addition on Corn Grits Extrusion Cooking

¹Département de Génie Chimique, Université de Technologie de Compiègne BP 529 Centre de Recherches de Royallieu, 60205 Compiègne Cedex, France. Present address: Département de Génie des Procédés Alimentaires, Ecole Nationale d'Ingénieurs des Techniques des Industries Agricoles et Alimentaires, Domaine de la Géraudière, BP 82225-44322 Nantes Cedex 03, France. ²Corresponding author. Phone: (33) 02-51-78-54-61. Fax: (33) 02-51-78-54-67. Email: desrumau@enitiaa-nantes.fr ³Clextral SA, Zi du Chazeau, BP 10, 42702 Firminy, France. ⁴Nestle R&D Center, 1350 Orbe, Switzerland.

The influence of added fatty acids on extrusion cooking of corn grits and extrudate properties was studied. Samples with three average corn grits particle sizes were processed in a twin-screw extruder; fatty acids content (0.2–0.8%, wb) varied, and experimental conditions were kept constant (moisture content 18.4% wb, barrel temperature 150°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 fatty acids were added, water solubility and absorption indices decreased, radial expansion index decreased, longitudinal expansion index increased, number of cells increased, and mechanical resistance of extrudates decreased. The influence of added fatty acids was attributed to the formation of fatty acids-amylose complexes.