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

• Masas from control and nixtamalized corn were prepared after protein fractions extraction.
• Protein fractions were analyzed by SDS electrophoresis.
• Albumins and globulins stabilized starch crystals increasing gelatinization enthalpy in nixtamalized samples.
• All masa samples behaved as weak viscoelastic gels, with predominance of the storage modulus.
• Thermal and rheological differences were due to lime-polymerized protein-starch network.

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 residual components. Proteins were sequentially extracted from nixtamalized and control corn samples. Masas resulting 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 corn samples cooked with lime, interactions albumins-lime and globulins-lime could probably be taking place and these interactions stabilized the starch crystals. However, zeins and glutelin-like proteins probably interacted with gelatinized starch, weakening its crystal integrity. Rheological characterization showed that all masas, behaved as “weak-gel- like materials”, with a predominating elastic behavior (G′ > G″), over the involved frequency range. The elastic rheological response might be attributed to the formation of a lime-polymerized protein-starch network and G′ and G″ were affected by the applied treatments.