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_1.87O_0.81N_0.06S_0.0015, CH_1.90O_0.82N_0.05S_0.0019 and CH_1.76O_0.73N_0.06S_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.