Effect of processing and germination on the nutritional and bioactive properties of black amaranth ( Amaranthus hybridus ) cultivated over 2,700 m above sea level in Apurimac

Black amaranth (Amaranthus hybridus), an Andean pseudocereal, was evaluated to assess the effects of germination, roasting, and cooking on its nutritional profile, protein structure (SDS‒PAGE and FTIR), color, polyphenol content, antioxidant capacity (DPPH and ABTS), and flavonoids. Grains from Atancama and Marcahuasi (Apurimac, Peru) were analyzed using analysis of variance, Tukey's test (p < 0.05), and principal component analysis (PCA). Proximate analysis showed that both roasting and germination increased the protein content from both locations, notably more, and crude fiber. Increases were also observed for polyphenols, antioxidant capacity, and flavonoid content. Glutelin and globulin fractions exhibited greater structural stability, maintaining protein quality during processing, while albumins and prolamins were partially degraded, facilitating the release of polyphenols and flavonoids. PCA revealed a strong correlation between color parameters (L*, a*, b*) and antioxidant capacity. These results suggest that germination and roasting enhance the nutritional and functional properties of black amaranth, supporting its application as a nutraceutical ingredient.