Effect of extrusion feed moisture content on physico-chemical properties of sorghum cowpea composite extrudates

Abstract

The blending of common staple foods and the application of suitable processing technologies can facilitate the development of food products with high energy and nutrient density. This study investigated the effect of feed moisture content on the physicochemical properties of sorghum-millet-cowpea composite flour extrudates. A composite flour containing sorghum, cowpeas and finger millet was extruded at two levels of feed moisture content namely, 10% and 20% while other extrusion conditions were kept constant. Proximate composition, physical, chemical, pasting and functional properties of the extrudates were determined. The results showed that increasing the feed moisture content significantly affected (p˂0.05) the expansion ratio, bulk density, hardness and moisture content of the extrudates. Increasing the feed moisture content significantly affected (p>0.05) the proximate composition of the extrudates. The functional properties of the flours made from the extrudates were higher (p<0.05) than those of the control (unextruded) flour. Extrusion generally reduced the peak time, peak, final and setback viscosities. The findings promise potential application in production of instant composite flours for porridges.