Effect of some extrusion variables on fermented maize-soybean blend.

The effects of feed moisture, sugar and temperature on extrusion of fermented maize-soybean blend was investigated. Fermentation caused a reduction in sectional expansion index from 1.342 to 1.244, bulk density from 0.5005 to 0.5002 g/cm3 and water absorption index (WAI) from 5.9 to 5.2 but increased specific volume from 7.13 to 7.15 cm3/g and water solubility index (WSI) from 1.2 to 1.7. Increase in feed moisture (20-35 %) reduced sectional expansion index, specific volume, bulk density and water solubility index but increased the water absorption index. An increase in concentration of the sugar reduced extrudate sectional expansion index, specific volume and water absorption index but increased bulk density and water solubility index. Increasing the barrel temperature exhibited a predominant effect on the bulk density of the extruded products. Proximate composition of the samples revealed that the extrudate was high in protein content (between 19.2 and 23.0 %), low in fat and ash contents.