Chemical Composition, Thermal Behavior, and Structural Characteristics of Lupinus mutabilis Sweet Flours from the Southern Peruvian Andes

Andean crops can be efficiently incorporated into food industrialization after the characterization of their components. This study evaluated tarwi (Lupinus mutabilis Sweet) flours from three ecotypes: PNTF (punto negro), WTF (white), and MTF (moro), with a particle size of 125 µm, analyzing their color, proximate composition, amino acid profile, bioactive compounds, and spectroscopic, thermal, and microstructural properties. Significant differences among ecotypes were determined at p < 0.05. The white ecotype showed greater accumulation in Dx (50), while black point exhibited the highest Dx (90), indicating a higher proportion of large particles. Regarding color, WTF presented the highest lightness and whiteness index, PNTF intermediate values, and MTF the darkest coloration, with greenish tones in black point and reddish tones in moro. The MTF ecotype showed the highest protein content (56.28%) and higher levels of essential amino acids, with methionine being the limiting amino acid. It also contained phenolic compounds ranging from 29.97 to 35.49 mg GAE/100 g, flavonoids from 9.36 to 10.8 mg quercetin/100 g, and antioxidant capacity measured by DPPH ranging from 25.79 to 55.30 mg TE/100 g, particularly notable in MTF. PNTF stood out for its dietary fiber (5.93%) and carbohydrate (17.22%) content. Infrared spectroscopy analysis revealed a similar macromolecular fingerprint among the samples. Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) indicated greater thermal stability in MTF. Scanning Electron Microscopy (SEM) revealed greater compaction of irregular particles in MTF and greater dispersion in PNTF. These results support the differentiated valorization of tarwi ecotypes as complementary raw materials for the development of high-value-added foods in the current food industry.