Structural, thermal and energetic properties of Andean-pseudocereal flours with high nutritional values

Structural, thermal and energetic properties of quinoa, kiwicha and kañiwa native Andean-pseudocereal flours have been studied. Moisture, protein and fat contents and also metallic and semi-metallic levels were, in general, within of the range values reported in the literature. Empirical formulas of quinoa, kiwicha and kañiwa flours have been determined as CH 1.87 O 0.81 N 0 . 06 S 0.0015 , CH 1.90 O 0.82 N 0 . 05 S 0.0019 and CH 1.76 O 0.73 N 0 . 06 S 0.0017 , respectively. The elemental carbon concentration (C flour ) in organic matter follows the trend, C kañiwa (45.6%) > C kiwicha (43.2%) ≈ C quinoa (43.3%), which reflects the greater structural similarity between the quinoa and kiwicha flours, with respect to kañiwa flour. Regarding thermal and energetic properties: (i) in the temperature range of 261.15–343.15 K, we found no significant differences among the specific heat capacities of the three flours, which are ranged between 1.3 and 1.9 J g −1 K −1 ; (ii) the organic matter decomposition temperature ( T dec ) followed the trend, T dec,kañiwa (489.8 ± 1.6 K) > T dec,kiwicha (479.1 ± 1.5 K) ≥ T dec,quinoa (477.1 ± 1.5 K) indicating a greater thermal stability range of kañiwa flour; (iii) the gelatinization temperatures and also the gelatinization enthalpy of kañiwa flour (4.3 ± 1.6 J g −1 ) were lower than corresponding thermal gelatinization parameters of quinoa and kiwicha flours; and (iv) the standard massic energy of combustion (− Δ c u °) or its associated net calorific value ( q NCV ) of kañiwa flour (18.77 ± 0.15 kJ g −1 or 4487 ± 36 kcal kg −1 ) was slightly greater than for kiwicha (18.47 ± 0.11 kJ g −1 or 4415 ± 26 kcal kg −1 ) and quinoa (18.60 ± 0.16 kJ g −1 or 4445 ± 39 kcal kg −1 ) flours. Taking into account the associated uncertainties, q NCV trend is similar to the C flour and T dec trends. Accordingly, our results indicate a greater range thermal stability and greater net calorific value for kañiwa flour than for kiwicha and quinoa flours.