Influence of spelt flour addition on properties of extruded products based on corn grits

• The effects of spelt flour addition on properties of corn grits extrudates were studied.
• The addition of spelt flour decreased expansion and fracturability, but increased bulk density and hardness.
• Extrusion process and spelt flour addition significantly changed color and viscosity.
• Extrusion increased WAI, WSI and starch damage, while decreased resistant starch.

Production of corn extrudates with addition of various types of flours is widely used in the food process industry, both for final products and for the modification of flours for the bakery industry. Because of its chemical composition spelt is recently used for production of various types of food products. The aim of this study was to determine the effect of spelt flour addition to corn grits (ratios grits: flour = 95:5; 90:10 and 80:20) on extrudates properties. Prepared samples with 15% of moisture content were extruded in the laboratory single screw extruder, and then physical and rheological properties were determined.The obtained results showed that addition of spelt flour to corn grits resulted in decrease of expansion ratio (ER) and fracturability, whereas bulk density (BD) and hardness of extrudates increased. After extrusion process water absorption index (WAI), water solubility index (WSI) and damage of starch (DS) significantly increased, while resistant starch (RS) content decreased. Spelt flour addition and extrusion process significantly changed the color, decreased peak, hot and cold viscosities, and the extruded samples were less prone to retrogradation.