Rice Polishing Machine

The white rice milled by the rice mill to the standard one-meter accuracy flows down from the feed port into the polishing room, and at the same time, the heated water (used when the room temperature is lower than 15°C) is passed through the flow meter through the rubber tube through the temperature-controlled water tank. The air-water mixing nozzle forms water mist through high-pressure air and enters the hollow main shaft impingement area.

Under the action of strong negative pressure suction, the water mist passes through the main shaft and the vent holes of the polishing roller and enters the surface of the polishing roller to mix with rice and adhere to it. On the surface of the rice grain, the surface of the rice grain is moistened and softened. Through the rotating movement of the polishing roller in the polishing chamber, the rice grains are continuously moved in the polishing chamber.

During the movement, relative movement, relative friction and squeezing occur between the rice grains, between the rice grains and the polishing roller, and between the rice grains and the rice sieve. Because the surface of the rice grains is wet and soft, this friction will remove the bran powder and acne on the surface of the rice grains on the one hand. On the other hand, the starch layer on the surface of white rice undergoes gelatinization and crystallization during the friction extrusion process to form a bright protective film, which improves the surface finish and prolongs the storage time of the later rice. The fine rice bran and fine chips produced during the polishing process are removed from the machine through the rice sieve under the action of negative pressure and strong suction.

Polishing of rice grains is done primarily for aesthetic and practical reasons, not for health benefits. Unpolished or brown rice is indeed more nutritious than polished white rice, as it retains more of the bran and germ layers which are removed during the polishing process.
The main reasons rice is polished include:
● Appearance: Polished white rice has a more uniform, appealing appearance preferred by many consumers. The brown bran layer of unpolished rice can be seen as less visually appealing.

● Shelf life: Polishing removes the oil-rich bran and germ, which can cause the rice to go rancid more quickly. Polished white rice has a longer shelf life.

● Texture and cooking properties: Polished rice has a softer, more delicate texture that some prefer. The bran in brown rice can make it chewier and harder to cook evenly.

● Cultural preferences: In many cultures, polished white rice is the traditional and preferred form, seen as more refined and desirable.
While unpolished brown rice is indeed more nutritious, retaining vitamins, minerals, and fiber, polished white rice remains the more common commercial product due to consumer demand and practical considerations around appearance, shelf life, and cooking properties.