High oil content maize: Physical, thermal and rheological properties of grain, masa, and tortillas

The objective of this study was to assess thermal, rheological and quality properties of grain, masa (ground nixtamalized corn), and tortillas made with high-oil maize hybrids and compare them with landraces. Grains of high-oil hybrids were harder (flotation index 10-36) with high onset, peak and final gelatinization temperatures, which were reflected in lower masa and tortilla yield. However, the tortillas had higher oil content (3.2-4.5 g/100 g) than those made with landraces (2.9-3.0 g/100 g). Tortillas made with the yellow hybrids were softer (1.8 N). Pepitilla had the highest viscosity in grain, masa and tortillas, reflected in greater water absorption and masa and tortilla yield (1.61 kg/kg maize). A close relationship was found between G′ and G″ and retained pericarp and oil content in masa; higher content of natural gums produced firmer masa with higher viscoelasticity. The high oil content in tortillas reduced their water absorption and starch swelling capacity but inhibited starch retrogradation, so they remained softer during storage.