EFFECT OF EXTRUSION COOKING ON PHYSICAL PROPERTIES AND CHEMICAL COMPOSITION OF CORN-BASED SNACKS CONTAINING AMARANTH AND QUINOA: APPLICATION OF PARTIAL LEAST SQUARES REGRESSION

The effects of amaranth and quinoa supplements and extrusion-cooking on the physical properties and chemical composition of corn-based extrudates were investigated by using PLSR and L-PLSR. Grain type, content of amaranth or quinoa flour (20-50% of solids of blend), temperature of die (140-160 degrees C), screw speed (200-500 rpm), water content of mixture (14-18%) as well as contents of protein, ash, dietary fiber and main fatty acids of blend were the predictors in the PLSR and L-PLSR. Water content of mixture and screw speed had the distinctly greatest importance for physical response variables such as torque and pressure at the die during extrusion, SEI, stiffness and water content of extrudate. Extrusion reduced the content of fatty acids and tocopherols in the solids but it had only a slight effect on the content of total phenolic compounds and folate. This study proved that extrudates containing up to 50% amaranth or quinoa can maintain some key physical properties (e.g., high SEI, low stiffness) and the added nutritional value (e.g., increased content of folate). This study applied successfully PLSR and L-PLSR modeling techniques to study the incorporation of amaranth and quinoa to corn-based snacks.