Extrusion of defatted soy flour-hydrocolloid mixtures

Defatted soy flour containing low levels of added hydrocolloid (either sodium alginate or methylcellulose) was thermoextruded in a laboratory single-screw extruder, and the effect of operating parameters on selected textural properties (maximum peak force, determined in an Ottawa Measuring (OTMS) cell, and chewiness) and physical properties (bulk density and water absorption capacity) were studied. Adding sodium alginate generally increased OTMS peak force, chewiness and water absorption capacity and increased bulk density. Extruding at a feed moisture content of 22% w/w resulted in the best properties, regardless of the levels of other independent variables. Maximum force and chewiness were positively correlated while bulk density and water absorption capacity were negatively correlated to each other.