Optimisation and studies on lentil and pumpkin incorporated barley extrudates

Barley based extruded snacks containing pumpkin and lentil were produced using a twin screw extruder. Response surface methodology was used to optimize and evaluate the effect of three independent variables viz. feed composition (50-90% barley flour; 2.5-42.5% lentil flour and 7.5% pumpkin flour), moisture content (13%-21%) and barrel temperature (115-155 °C) on lateral expansion, bulk density, water absorption index, water solubility index, specific mechanical energy and breaking strength of extrudates. Low barrel temperature and low moisture content were found to enhance the lateral expansion (37-70.8), whereas low barley content significantly reduced lateral expansion of the extrudates. A significant increase in water absorption index was (5.34-6.23 g/g) observed at high moisture content. The negative regression coefficients of feed composition, barrel temperature and moisture content revealed that these parameters reduced water solubility index of the extrudates. Higher moisture content depicted positive effect on breaking strength (178.71-325.77 N), whereas increased barley content significantly reduced breaking strength. Lower values of bulk density were observed at lower values of moisture content. Low moisture content significantly reduced bulk density. The specific mechanical energy of barley based extrudates ranged from 221.07 to 327.45 W hr/kg, a significant decrease in specific mechanical energy was observed at low moisture content. Feed composition, high moisture content and high barrel temperature enhanced the luminosity, redness and yellowness of extrudates. The extruded samples were evaluated organoleptically for appearance, texture, flavour and overall acceptability by a semi-trained panel of 10 judges using a 5 point scale