Grain Polishing Machine Manufacturers

Grain polishing in rice and grain milling

Grain polishing removes the outer bran layers and produces a bright, glossy surface on the milled grain kernel. In rice milling, polishing is the stage after whitening that produces the characteristic shine consumers associate with premium white rice. Polishing machines use a combination of friction (grain-on-grain abrasion as grains are pushed through a cone, drum, or cylinder) and water mist (a small quantity of water is sprayed onto the grain in the polisher, creating a gelatinised starch layer on the surface that fills micro-cracks and produces a bright, smooth finish when the water evaporates). The degree of polishing affects the surface appearance of the rice, the residual bran content, and the nutritional profile (polishing removes more of the remaining aleurone layer, reducing B vitamins and minerals). For premium export rice and high-value domestic branded rice, water mist polishing is the standard. In wheat milling, wheat grain scouring (a similar abrasive process) is used as a cleaning step rather than for cosmetic polishing.