Structural, functional, thermal and rheological properties of nixtamalised and extruded blue maize (Zea maysL.) flour with different calcium sources

Summary The effects of different concentrations of calcium hydroxide [Ca(OH) 2 ] and calcium lactate [C 6 H 10 O 6 Ca] on the functional and physical properties of extruded ( EF ) and nixtamalised ( NF ) blue maize flours were evaluated. Calcium source and concentration showed no significant effects on the EF expansion index. The water absorption index ( WAI ) of EF decreased as the concentrations of both calcium sources increased, and NF with C 6 H 10 O 6 Ca had the lowest WAI . The thermal and pasting properties of NF s were higher than those of EF . NF with C 6 H 10 O 6 Ca showed the highest final viscosity (FinV), indicating less damage to the starch granules, and this was correlated with microscopic analysis. In contrast, the FinV of EF s was significantly affected by calcium source and concentration. Extrusion with 0.3% and nixtamalisation at 2.95% of C 6 H 10 O 6 Ca yielded high WAI value and the best rheological properties in maize flour, respectively. These results suggest the use of C 6 H 10 O 6 Ca in extrusion or nixtamalisation to produce blue maize flours for tortilla or snacks with antioxidants.