Effect of feed moisture, variety and single screw extrusion on physicochemical properties and acceptability of grain sorghum
David Iordehiin Gbenyi, Iro Nkama, Mamudu Halidu Badau
Four (4) cultivated varieties of sorghum were extruded in a single-screw extruder. Extrusion was done at 15, 20 and 25% feed moisture and a temperature of 130OC at 140 rpm screw speed and 2 mm die diameter. The grain dimensions and proximate composition of the sorghum cultivars were determined using standard procedures. The water absorption index (WAI), water solubility index (WSI), bulk density (BD) and expansion ratio (ER) of the extrudates were also determined. The grain thickness, length, width, weight, volume and density varied from 2.26 to 2.87 mm, 4.16 to 4.99 mm, 3.57 to 4.18 mm, 24.57 to 42.56 g/100grains, 25.61 to 61.00 cm3 and 0.709 to 0.942 g/cm3 respectively. There was significant difference (p<0.05) in grain thickness, length, width, volume and density respectively. The proximate composition of the sorghum varieties were; Carbohydrate 71.22 to 73.94%, protein 10.36 to 11.20%, moisture 10.67 to 11.64%, crude fat 2.34 to 4.51% and ash 1.85 to 2.41% respectively. The crude fibre content of the sorghum grains ranged from 2.0 to 2.4% with Chakalari white recording the lowest value while Kanoline had the highest value. The physical and functional properties of sorghum extrudates varied from 1.86 to 5.68 for expansion ratio and 0.134 to 1.114 g/cm3 for bulk density. The water absorption index of the sorghum extrudates varied from 3.97 to 6.21 g H2O/g sample while the WSI of the sorghum extrudates ranged from 3.7 to 9.07%. There was significant (p˂0.05) variation in the grain dimensions, proximate composition, physical properties and water absorption behaviour of the sorghum varieties.