Properties of corn grits extrudates with addition of wheat bran
Extrusion, classified as a high temperature/short time process, is an important food processing technique used worldwide for the production and modification or improvement of quality of various products. The aim of this study was to determine the effect of wheat bran addition to corn grits (ratio grits:bran = 80:20) on properties of extrudates. Wheat bran are readily available and low cost by-product, and contain a large amount of dietary fibers. Prepared samples with 15% of moisture content were extruded in the laboratory single screw extruder at temperature profile 135/170/170 °C, using screw with compression ratio 4:1 and die with 4 mm diameter. Obtained extrudates were air-dried, and expansion ratio, texture, viscosity and fibre content were determined. The obtained results showed that addition of wheat bran to corn grits resulted in decrease of expansion ratio (ER) and fracturability, whereas bulk density (BD) and hardness of extrudates increased. Extrusion process resulted in increase of water absorption index (WAI) and water solubility index (WSI), but in decrease of peak, hot and cold viscosity. Addition of wheat bran to corn grits resulted in increase of fibre content, and extrusion cooking didn’t significantly influence fibre content. The obtained extrudates can be used as final products or as modified flours in bakery industry.