Effect of Composition of Ingredients, Temperature and Screw Speed on Nutritional, Functional and Sensory Properties of Tuber Crop Extrudates

In the present paper tuber crop extrudates has been prepared from Arrowroot flour, Lesser yam flour and Potato flour. Potato flour has been taken as base flour 50% and rest of the two flours varied i.e. Arrowroot flours were (0, 10, 20, 30, 40 and 50%) and Lesser yam flour (50, 40, 30, 20, 10 and 0%). These three flour combinations at 10% MC (db) were extruded using twin screw extruder at screw speed 330, 360 and 390 rpm and barrel temperature 130, 150 and 170°C. The extrudates were analysed for its physico-chemical properties (moisture content, protein, fat, crude fibre, ash content, carbohydrates and colour) and functional properties (water absorption index, water solubility index, expansion ratio, bulk density and hardness). The sensory analysis of the developed extrudates was performed through a panel of 45 trained judges for all 54 samples. The extrudates were optimized for its desirable better functional properties (like lower bulk density, more expansion ratio, lower hardness; protein, fat, fibre, ash and carbohydrates). The optimum extrudates combination was observed at flour combination (Arrowroot: Lesser yam: Potato as 10:40:50) at screw speed 385-390 and temperature 130-135°C. The functional properties at optimum zone was 0.15 g/cm³, 3.10, 1460g, 4.22g/g and 31.30% bulk density, expansion ratio, hardness, water absorption index and water solubility index respectively. The nutritional properties at optimum zone was 2.80%, 1.40%, 1.96%, 85.01%, 1.20% and 6.0 % (db) protein, fat, ash, carbohydrates, fibers and moisture content respectively. The sensory score was highest at Arrowroot: Lesser yam: Potato (10:40:50) at 390 rpm screw speed and 130°C temperature. The sensory properties at the optimum zone was 7.5, 7.2, 8.5, 7.4, 7.0, 7.3 and 7.5 i.e. appearance, colour, taste, texture, crispiness, expansion and overall acceptability respectively.