Extrusion Lab Report

Extrusion process

Extrusion experiments were carried out using a laboratory-scale co-rotating and intermeshing twin-screw extruder (Model BC 21, Clextral, Firminy, France). The screws of the extruder were 25 mm in diameter and 400 mm in length. The barrel which contains screws was divided in to four zones; the temperature of the first, second and third zone during extrusion cooking was maintained at 40, 70 and 100oC respectively, while the temperature of the fourth zone was changed according to each run of experimental design. The die has four openings with diameter of 1.5 mm for each; extrudates were cut by controlled speed cutter with four bladed knives attached with the die. Extruder was operated by 8.5 kilowatt motor with speed range from 0 to 682 rpm. A single screw volumetric feeder (D.S. and M, Modena, Italy) was utilized to adjust the feeding rate of the flour mixture. Feed moisture was controlled by injecting the water into the extruder by a water pump.

Product responses

SME

SME (Wh/kg) was calculated from the values of actual screw speed, rated

Extruded samples were ground using laboratory-scale super mill (type 3303, Perten Instruments AB, Sweden) and passed through 200 μm sieve. Ground samples of 1 g was mixed with 2 ml distilled water and kept at room temperature for 1-2 h to reach equilibrated moisture content. A hermetic aluminium pan was filled with 20 to 30 mg of the preconditioned samples and inserted into the DSC; samples were heated from 20 to 100oC at a heating rate of 10oC/min; a sealed empty sample pan was considered as a reference. Measurements and calculations were carried out by thermal analysis software (STARe system, version 9.20). DG was estimated by comparing enthalpy (ΔH) of extruded samples with that of raw flour mixture according to Marshall et al. (1993) and Kraus et al. (2014) by using the following