Optimization of an Extruded Formulation to Enhance Protein Content in Corn Grits-based Products Using Quinoa and Its By-products

Quinoa by-products remain an underutilized and valued alternative in developing protein-enriched extruded cereals, while maize grit-based formulations often lack sufficient protein content. To address both challenges, this study aimed to optimize the formulation of an extruded cereal by incorporating corn grits, quinoa flour, and quinoa agro-industrial residues, leveraging quinoa’s high protein content and adding value to its by-products. The extreme vertices mixture design method was applied using Minitab® 2019 for statistical modeling. The independent variables included corn grits, quinoa flour, and agro-industrial residues, while the dependent variables were protein content, expansion index, bulk density, and extrudate hardness. The optimal formulation was identified through a desirability test based on fitted regression models, maximizing protein content and expansion index while minimizing hardness and bulk density. The optimal composition consisted of 57.17 % corn grits, 34.3 % quinoa flour, and 8.5 % agro-industrial residue. The physicochemical analysis of this optimized formulation revealed a protein content of 10.83 %, an expansion index of 3.04, a bulk density of 0.193 g/cm3, and a hardness of 22.31 N. These findings suggest that incorporating quinoa by-products into extruded cereal formulations enhances the nutritional profile without significantly compromising key physicochemical properties such as expansion index and bulk density.