Milling is an essential step in the post-production of rice. The goal of rice milling is to reduce mechanical stresses and heat build-up in the grains i.e. by removing the layers of husk and bran, to yield edible, uniformly polished grains free of impurities.
Rice milling involves three basic stages; that of cleaning and husking, whitening and polishing, and finally the grading, color sorting, packaging and storage.
- The pre-cleaning stage removes impurities and unfilled grains from the paddy.
- Husking/Hulling removes the husk from the paddy.
- Husk aspiration separates the husk from the unhusked paddy/brown rice.
- Paddy separation involves separating from the brown rice, the unhusked paddy.
- De-stoning, as the name suggests is separating small stones from the brown rice.
- Whitening involves removing all or part of the bran layer from the brown rice.
- Polishing is the process of enhancing the appearance of the milled rice by polishing the exterior of the milled kernel. This is the step that makes the final product visually appealing, transforming the grains into rice pearls.
- Sifting to remove small impurities or chips.
- Length grading to segregate the small and large broken from the head rice.
- Blending that is a predetermined mix of head rice with broken, in accordance to the consumer demands.
- Weighing and bagging is getting the milled rice ready for transport.