Thermal and rheological properties of masa from nixtamalized corn subjected to a sequential protein extraction.

The aim of this work was to study the effect of a sequential extraction of proteins from nixtamalized corn(Zea mays L) on the thermal and rheological properties of the resulting dough (masa) from the residualcomponents. Proteins were sequentially extracted from nixtamalized and control corn samples. Masasresulting after each protein fraction extraction were subjected to thermal analysis and rheological tests.The thermogram data suggested that, even though albumins and globulins were in small amount in cornsamples cooked with lime, interactions albumins-lime and globulins-lime could probably be taking placeand these interactions stabilized the starch crystals. However, zeins and glutelin-like proteins probablyinteracted with gelatinized starch, weakening its crystal integrity. Rheological characterization showedthat all masas, behaved as ?weak-gel- like materials?, with a predominating elastic behavior (G0 > G00),over the involved frequency range. The elastic rheological response might be attributed to the formationof a lime-polymerized protein-starch network and G0 and G00 were affected by the applied treatments.