5th Grade - Social Studies

LESSON PROBLEM: Economics: How is harvested rice made ready to eat?


STUDY GUIDE


Even after rice is harvested, threshed, winnowed and cleaned, it is still not yet ready to be eaten. In order for the rice to be ready for cooking, it has to undergo the process of milling. Traditional, manual processes are used to mill a majority of the cultivated rice in the world. A much smaller percentage of rice is milled in modern rice mills.

The Husk and Skin of Rice
Rice is an edible grain inside an inedible protective tough outer husk, which is called the hull. This hull or shell must be removed (shelled) before the rice can be eaten. Beneath the hull is a bran layer, which forms the skin of the seed. During the milling and polishing process, this layer is also removed to reveal the white grain. While most grains, like wheat, are ground to fine flour before use, rice is mostly eaten as a whole grain.

Manual Milling of Rice
In the traditional process of underdeveloped countries, rice is shelled by hand. This work is very hard. It is most often done by women who crush the rice by pounding it in a wooden bowl with thick wooden staffs. The staffs are hard enough, to break the grain free from the hull without damaging the grain. After the pounding, it has to be winnowed again to get rid of the husk. This chaff is removed by allowing air to flow through the grain, sometimes done by tossing or fanning the grains. To remove the bran, the farmers rub the rice on a metal sieve leaving the white rice.

When the rice is milled by hand, some bran is left on the grain. When the rice is milled in small local mills all of the bran is removed. These small mills have rollers rotating inside metal drums, which remove the hull but keep the grain intact.

The by-products of the traditional milling process: the husk, bran and broken rice pieces are used either as chicken feed or as fuel.

Modern Rice Mills
Twenty-five percent of the worldÂ’s rice crop is processed in large modern rice mills, which can mill as much as one thousand tons of rice a day. Rice is poured in at one end of the mill. It is winnowed and re-winnowed to clean it of the last bits of unwanted chaff (seed covering) and dirt. Winnowing in the rice mills is done by passing the grain through a series of seives.

Pearling of Rice
After it is hulled (the husk is removed), the grains are pearled, which means their bran layers are removed. This can also be called milling or polishing the rice. Because most consumers like white rice, the grains are often also polished by an abrasive process where the grains are rubbed against each other and the special surface of the polishing machine.

Grading of Rice
The finished rice is graded according to the amount of broken rice it contains. The lower the proportion of broken grain, the higher the quality of rice. Machines do the grading. Modern electronic sorting machines classify the size, the type and the color of each batch of rice; and automatically separate the different grades for packing. These modern sorting machines have electric "eyes" that look at each grain of rice. Rice that is broken or discolored is not accepted. These machines make rice sorting very fast and efficient. Some rice producing countries like Indonesia and India, do have large commercial mills. Most of the rice consuming countries have also set up commercial mills, preferring to import rough rice, and then process it locally. Britain and Holland follow this practice.

By-Products of Milling
The by-products of milling are as valuable as the rice itself. Husk, bran, and polish are carefully separated and sold for different uses, like fuel, vitamins and animal feed. You might wonder what polish is. Perhaps, shoe polish, nail polish or other polishes come immediately to mind. However, in rice processing, polish is fine rice powder produced during the polishing process.

After this long process rice is finally ready to be traded, and consumed.




ACTIVITIES

Find a rice mill in your area and visit it. If you are not near a rice mill, find information on the Internet about a rice mill. Learn how the mill processes rice. Observe the different processes being performed in the mill. Make a chart of the different processes in milling rice.




EXTENDED LEARNING

In your geographic area, study climate, land type, and its suitability for rice cultivation. Develop your own general criteria for rice production where you live.










VOCABULARY
  • polishing
  • abrasive
  • pearling
  • hull
  • winnow
  • chaff


Click here to play Rice Rampage!
American Rice:
More than 90% of the rice eaten in the United States is grown by U.S. farmers.
Click here to learn more about where Rice is grown in the United States.
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