Interactions of Native Maize Starch Components with Pectin Using Extrusion

Native starch exhibits undesirable properties in the final product when used as an additive. Recently, the effects of the interaction between starch and hydrocolloids on the techno-functional properties of starch have been studied. However, this interaction has not yet been applied to a real food system. Therefore, in this work, the techno-functional properties of starch-pectin complexes formed by extrusion are investigated. Mixtures of isolated native Pozolero maize starch "HPZ1" and pectin of low degree of methyl-esterification at four concentrations (0%, 2%, 5%, and 7%) are used. The starch-pectin blends are processed in a single screw extruder with constant variables: temperature, screw speed, and moisture. Morphology, X-ray diffraction, thermal properties, and techno-properties are studied. A protective effect of pectin on the starch granules is observed, as evidenced by a matrix involving starch granules. Extrusion results in a partial gelatinization of the starch granules and alters their thermal and pasting properties with the peak temperature increasing with increasing pectin concentration. Extrusion allows both carbohydrates to interact with each other. Finally, the results show that the starch-pectin complexes are ingredients with desirable techno-functional properties that can be integrated into a food system and add value to Mexican criollo maize. Extrusion causes a partial gelatinization of starch granules and alters their thermal and pasting properties with the peak temperature increasing with increasing pectin concentration. This thermo-mechanical process allows both carbohydrates to physically interact with each other.image