Effect of proteins on the formation of starch-lipid complexes during extrusion cooking of wheat flour with the addition of oleic acid

The formation of starch-lipid complexes plays an important role in extruded products. The effect of gluten proteins on thermal conditions at which the starch-lipid complexes formed during extrusion cooking of wheat flour with the addition of oleic acid was evaluated, considering wheat starch as a reference. The presence of gluten proteins in wheat flour extrudates brought about a reduction of the formation of starch-lipid complexes compared to blend of wheat starch and oleic acid extruded at the same operating conditions (melting enthalpy: 0.4 vs. 1.6kJkg(-1)). Moreover, the lubricant effect of oleic acid observed during extrusion of wheat starch (low values of specific mechanical energy and residence time) was not found during extrusion of wheat flour with addition of oleic acid because of the interaction between gluten proteins and oleic acid. This research points out the importance of proteins on biopolymer modifications and their effect on extrudate quality.