Effects of location and spacing of reverse screw and kneading element combination during twin-screw extrusion of starchy and proteinaceous blends

Abstract

The influence of location and spacing of reverse screw and kneading elements on specific mechanical energy input and product attributes during twin-screw extrusion of rice flour and pink salmon blends was investigated. The incorporation of reverse screw and kneading element combination increased the specific mechanical energy, expansion ratio and water solubility index but decreased bulk density and Warner-Bratzler (WB) shear stress. The opposite trend was observed with increasing fish content, except for shear stress which was little affected either for rice flour or its blends with 30% fish solids. A non-linear relationship existed between WB shear stress and specific mechanical energy for all the screw configurations and feed compositions studied. The WB shear stress and water solubility index were linearly related to bulk density and specific mechanical energy, respectively.