Performance analysis of a novel cyclone-type pneumatic rice polisher

Energy intensive commercial abrasive-friction rice polishing systems with heavy moving parts induces considerable breakage of rice. Jet polishing, used for metals with high speed air-abrasive particles, could be adopted to develop a simple pneumatic rice polishing system without any moving parts. Its construction is similar to a gas-cyclone system. The effect of four abrasive surfaces, viz., coarse (CR, 483 μm), medium (MD, 254 μm), fine (FN,122 μm) and very fine (VF, 89 μm) on degree of polishing (DP) and broken yield (Br) was studied. Particle-trajectory, particle-abrasive surface interaction, grain rotation pattern and progress of bran removal were also studied. DP and Br increased linearly with number of passes for all the abrasive surfaces. Higher DP (8.49 ± 0.2 and 8.49 ± 0.3%) with CR and MD was attributed to removal of bran layer along with endosperm fractions while FN and VF removed proportionally more bran layer (DP, 6.27 ± 0.3 and 8.31 ± 0.4%) with negligible endosperm fraction. Br was least (24.13 ± 0.5%) with VF and highest (34.0 ± 2.2%) with CR.