Rice is the main diet in many countries

Use and History of Rice

It is not usually eaten cooked or boiled. In some areas, such as Spain, rice is first fried in olive oil or butter, then cooked with water or soup. In other areas, such as India, rice is eaten with sauce or curry. Rice can also be used to make alcohol, such as Japanese sake.

Rice is mostly eaten steamed or boiled, but it can also be dried and ground into a flour. Like most grains, rice can be used to make beer and liquors. Rice straw is used to make paper and can also be woven into mats, hats, and other products.

Since it has been such an important grain worldwide, the domestication and cultivation of rice is one of the most important events in history that has had the greatest impact on the most people. When and where the domestication of rice took place is not specifically known, but new archaeological evidence points to an area along the Yangtze River in central China and dates back as far as 11,000 years. Researched by a team of Japanese and Chinese archaeologists and presented at the 1996 International Symposium on Agriculture and Civilizations in Nara, Japan, radiocarbon testing of 125 samples of rice grains and husks, as well as of rice impressions in pottery, from sites located along a specific portion of the Yangtze unanimously indicate a median age of over 11,000 years. Another discovery of possibly the oldest settlement found in China, which is located closely upstream from the other sites, gives credence to the new findings.

Preparation

  • 1 Prior to planting, minimal soil manipulation is needed to prepare for cultivation. If the rice will be grown on a hilly terrain, the area must be leveled into terraces. Paddies are leveled and surrounded by dikes or levees with the aide of earth-moving equipment. Then, the fields are plowed before planting. In the United States, rice is most often planted on river deltas and plowing is accomplished with a disk plow, an off-set disk plow, or a chisel. Adequate irrigation of the terrace or river delta bed is required and accomplished by leveling and by controlling water with pumps, reservoirs, ditches, and streams.

Planting

  • 2 Rice seeds are soaked prior to planting.
  • 3 Depending on the level of mechanization and the size of the planting, seeding occurs in three ways. In many Asian countries that haven’t mechanized their farming practices, seeds are sown by hand. After 30-50 days of growth, the seedlings are transplanted in bunches from nursery beds to flooded paddies. Seeds can also be sown using a machine called a drill that places the seed in the ground. Larger enterprises often found in the United States sow rice seed by airplane. Low-flying planes distribute seed onto already flooded fields. An average distribution is 90-100 lb per acre (101-111 kg per hectare), creating roughly 15-30 seedlings per square foot.

Harvesting

  • 4 Once the plants have reached full growth (approximately three months after planting) and the grains begin to ripen—the tops begin to droop and the stem yellows—the water is drained from the fields. As the fields dry, the grains ripen further and harvesting is commenced.
  • 5 Depending on the size of the operation and the amount of mechanization, rice is either harvested by hand or machine. By hand, rice stalks are cut by sharp knives or sickles. This practice still occurs in many Asian countries. Rice can also be harvested by a mechanized hand harvester or by a tractor/horse-drawn machine that cuts and stacks the rice stalks. In the United States, most operations use large combines to harvest and thresh—separate the grain from the stalk—the rice stalks.
  • 6 If the rice has been harvested by hand or by a semi-automated process, threshing is completed by flailing the stalks by hand or by using a mechanized thresher.

Drying

  • 7 Before milling, rice grains must be dried in order to decrease the moisture content to between 18-22%. This is done with artificially heated air or, more often, with the help of naturally occurring sunshine. Rice grains are left on racks in fields to dry out naturally. Once dried, the rice grain, now called rough rice, is ready for processing.

Hulling

  • 8 Hulling can be done by hand by rolling or grinding the rough rice between stones. However, more often it is processed at a mill with the help of automated processes. The rough rice is first cleaned by passing through a number of sieves that sift out the debris. Blown air removes top matter.
  • 9 Once clean, the rice is hulled by a machine that mimics the action of the handheld stones. The shelling machine loosens the hulls from the rice by rolling them between two sheets of metal coated with abrasives. 80-90% of the kernel hulls are removed during this process.
  • 10 From the shelling machine, the grains and hulls are conveyed to a stone reel that aspirates the waste hulls and moves the kernels to a machine that separates the hulled from the unhulled grains. By shaking the kernels, the paddy machine forces the heavier unhulled grains to one side of the machine, while the lighter weight rice falls to the other end. The unhulled grains are then siphoned to another batch of shelling machines to complete the hulling process. Hulled rice grains are known as brown rice.

Milling

Since it retains the outer bran layers of the rice grain, brown rice needs no other processing. However along with added vitamins and minerals, the bran layers also contain oil that makes brown rice spoil faster than milled white rice. That is one of the reasons why brown rice is milled further to create a more visually appealing white rice.

  • 11 The brown rice runs through two huller machines that remove the outer bran layers from the grain. With the grains pressed against the inner wall of the huller and a spinning core, the bran layers are rubbed off. The core and inner wall move closer for the second hulling, ensuring removal of all bran layers.
  • 12 The now light-colored grain is cooled and polished by a brush machine.
  • 13 The smooth white rice is conveyed to a brewer’s reel, where over a wire mesh screen broken kernels are sifted out. Oftentimes, the polished white rice is then coated with glucose to increase luster.

Enriching

The milling process that produces white rice also removes much of the vitamins and minerals found primarily in the outer bran layers. Further processing is often done in order to restore the nutrients to the grain. Once complete, the rice is called converted rice.

  • 14 White rice is converted in one of two ways. Prior to milling, the rice is steeped under pressure in order to transfer all the vitamins and minerals from the bran layers to the kernel itself. Once done, the rice is steamed, dried, and then milled. Rice that has already been milled can be submersed in a vitamin and mineral bath that coats the grains. Once soaked, they are dried and mixed with unconverted rice.

Byproducts/Waste

Straw from the harvested rice plants is used as bedding for livestock. Oil extracted from discarded rice bran is used in livestock feed. Hulls are used to produce mulch that will eventually be used to recondition the farm soil.

The Future

With one out of every three people on earth dependent on rice as a staple food in their diet and with 80-100 million new people to be fed annually, the importance of rice production to the worldwide human population is crucial. Scientists and farmers face the daunting task of increasing yield while minimizing rice farming’s negative environmental effects. Organizations such as the International Rice Research Institute (IRRI) and the West African Rice Development Association (WARDA), and Centro Internacional de Agricultura Tropical (CIAT [International Center for Tropical Agriculture]) are conducting research that will eventually lead to more productive varieties of rice and rice hybrids, use of less water during the growing season, decrease in the use of fresh organic fertilizer that contributes to greenhouse effect, and crops more resistant to disease and pests.

Different Rice Types

MOST COMMON