Antioxidant activity of amaranth flours obtained by extrusion and partial analysis of their protein quality in vivo

The antioxidant activity was evaluated and partially characterized of the in vivo protein quality of amaranth flours obtained by extrusion at three levels of feed moisture (HA) and two temperature levels (T). We performed proximal chemical analysis, total phenols (FT), and antioxidant activity (AA). Treatments with higher and lower levels of HA and T were evaluated in their protein quality using a murine model, commercial and unprocessed amaranth inflated flours were included as reference. The net protein ratio (RNP), apparent digestibility (DAN) and true nitrogen (DVN) were evaluated. The FT and AA decreased by 30 and 56%, respectively, due to the extrusion process. In vivo protein quality analysis showed that amaranth extrudates have higher DVN (85 and 86.72 % for the lower and higher levels of HA and T, respectively) with respect to inflated amaranth (84.55 %) and unprocessed amaranth (83.01 %). The RNP tests were significantly different between extruded flours (4.11-4.32), commercially inflated (3.76) and unprocessed (3.81). In conclusion, processing by extrusion improves RNP and protein digestibility, however, total phenols and antioxidant activity are diminished.