Hull-less barley flour supplemented corn extrudates produced by conventional extrusion and CO2 injection process

The effects of feed moisture content (20, 25%), exit-die temperature (80, 130 degrees C), and extrusion-cooking method (with/without CO2 injection) on beta-glucan (BG) levels and physicochemical properties of hull-less barley flour (HBF) supplemented (15, 30, 45%) corn extrudates were investigated. The highest HBF supplementation level (45%) resulted in higher BG levels (2.87-3.28%) in all extrusion conditions. In general, increasing feed moisture content from 20 to 25% and exit-die temperature from 80 to 130 degrees C resulted in small increases in enzyme resistant starch type-3 (RS3) levels. However, the investigated extrusion conditions did not form substantial amount of RS3 and the highest RS3 content was 540 mg/100 g. Lower feed moisture content and higher exit-die temperature resulted in higher water solubility (WS) and lower water-binding capacity (WBC) values. Cold-paste viscosity (CV) was observed in all extrudates. High WS and WBC values of extrudates and the existence of CV values in RVA curves indicated complete starch gelatinization.