Engineering properties and optimization of the dehulling process for hairless canary seed

Abstract

This work aimed to determine the engineering properties of hairless canary seeds (Phalaris canariensis L.) of the variety “CDC Maria” and the optimum combination of operating conditions of the dehulling process with a pilot-scale centrifugal dehuller. The engineering properties analyzed in this study were the principal dimensions, length (4.8 mm), width (1.95 mm) and thickness (1.41 mm); geometric mean diameter (2.36 mm); the sphericity (49.2%); apparent and true densities (752 and 1191.47 kg/m3, respectively); the porosity (0.37); 1000 grains weight (7.28 g); angle of repose (15.89°) and the static coefficient of friction (galvanized steel, 0.325; plywood, 0.372; aluminium, 0.316). For the process optimization, a two-variable Doehlert design was used, analyzing the effect of impact dehuller rotor speed (peripheral speed 30.4 to 47.1 m/s) and seed moisture content (10 to 14% d.b.) by maximizing the dehulling ability (DA) and maintaining the production of fines by 3%. Under the experimental conditions of 36.7 m/s (peripheral speed) and 10% d.b. (seed moisture), with a double pass through the dehuller, the optimum value of DA (94%) was obtained, with a fine production of 3%. The optimized dehulling process allows removing a large percentage (98%) of the canary seed hull.