Physicochemical, functional and structural characteristics of grains, flour and protein isolates of Indian quinoa lines

Abstract

The physicochemical and functional properties of grains, flour and protein isolates (QPI) from different quinoa lines were evaluated. Quinoa flour and protein isolates were characterised by high protein (14.1-15.4% and 78.7-86%, respectively) and phenolic content (419 to 655 mg GAE/100 g). Water and oil absorption capacity of QPI (2.0-3.6 g/g and 2.71-3.32 g/g, respectively) was significantly higher than quinoa flour (1.22 and 2.17 gand 0.9 and1.54 g, respectively). QPI showed desirable functional properties in terms of high foaming capacity (50.8 to 60.2%), foam stability (38.5 to 50.4%), protein solubility (30 and 53.3%), and emulsification index (EAI- 19.2-26.1 m²/g and ESI- 96.7-149.8 min, respectively). Digestibility of QPI ranged between 70.8 and 77.8% and was negatively correlated to random coils. Quinoa lines with higher grain density (GD) showed higher total phenol content (TPC) and WAC and lower FRSA and OAC. QPI with higher proportions of β-structure and random coils had enhanced protein surface activities leading to improved emulsification and foaming capabilities. Among the highly conserved polypeptides (PPs), variations were observed in accumulation of 53, 59 and 32 kDa PPs for grains and 33 and 21-24 kDa PPs for QPI.

Keywords: Antioxidant; Gel electrophoresis; Gluten free; Protein digestibility; Pseudo cereal.