Structural and textural characterization of corn–lentil extruded snacks

Structural and textural properties of extruded corn and corn–lentil mixtures were investigated as a result of process conditions, including extrusion temperature (170–230 °C), feed rate (2.52–6.84 kg/h) and feed moisture content (13–19% wb). Lentil was used in mixtures with corn flour at a ratio of 10–50% (legume/corn). Apparent density increased with feed rate, moisture content and material ratio and decreased with temperature, while expansion ratio showed an opposite behavior. Modulus of elasticity increased with feed composition and decreased with extrusion conditions. Number of peaks during compression decreased with extrusion temperature and feed composition. Similar behavior was also found for sensory evaluated structural and textural characteristics. The examination of macrostructure confirmed the effects of extrusion conditions and feed composition on structural and textural properties. The properties correlation revealed critical relationships among instrumental and sensorial characteristics. Hence, simple power model equations were developed, which enable their prediction and consequently the design of extruded snacks with acceptable quality characteristics.