The Parts of Rice Grains

The Parts of Rice Grains. (Image: sutteerug/iStock/GettyImages)

Rice is more than just an inexpensive filler, that part of the Chinese buffet you pass over when you're in search of your favorite lemon chicken or garlic ribs. Of the world's most widely grown grains, rice is the one that's most likely to be eaten directly by humans instead of being first served as animal fodder. It's a supremely versatile cooking ingredient, and it's found in more varieties than most other grains.

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There's a classic French form of rice pudding that would put your school cafeteria's offering to shame. The rice is cooked in cream until it's soft, then stirred into a sweetened vanilla custard and lightened with whipped cream. The whole confection is chilled in a mold, then turned out onto a plate and decorated with red currant jelly. If you think this dish sounds fit for a queen, you'd be right. It's said to have been a favorite of Napoleon III's wife Eugenie, and the French call it "riz a l'Impératrice," or "the Empress's rice," to this day.

That elegant dessert is a far cry from the simple rice balls of Japan or the bowl of rice porridge — jook, or congee — that's a down-home comfort food in China. Yet, whether it's eaten by a farm worker in Asia or an empress in France, rice is one of the world's most important staple crops. It's the daily diet of about half of the world's population, so understanding rice both as a food and a crop is well worth a few moments' reading.

Basic Rice Anatomy

Like all the other true grains, rice grains are the seeds of grasses, and they share the same basic anatomy as their cousins. The outer layer is a tough, inedible husk, designed to protect the grain from the elements as well as from other threats, including insects, molds and grazing animals. That outer layer must be removed to reveal the grain inside before the rice can be eaten.

Inside the husk, you'll find another layer of tough, fibrous material. That's the bran of the rice grain, which is rich in fiber, vitamins and oil. Most of the individual kernel makes up the next layer, called the endosperm. That's the starchy part containing most of the calories, and it's there to provide a source of food for a new plant to grow from the seed. The final part of the seed is the germ, or embryo, which is the infant rice plant. This part of the grain is also rich in oil, fiber and nutrients.

Rice Is Highly Adaptable

Rice is native to the tropical and subtropical parts of Asia, though you can find wild and cultivated rice all around the modern world. It's surprisingly adaptable within that range of climates. It's grown in relatively cool areas, including Europe and northern China, and on the steep mountainsides of Japan and India, yet it's equally at home in humid tropical river valleys or the sweltering plains of Africa.

Depending on the variety of seed that's grown, rice can mature in as few as 90 days, or it can take twice that, up to 180 days. As a rule, the more heat, water and sunlight the rice gets, the less time it takes to produce a crop. That's why tropical regions generally are able to grow multiple crops of grain each year. Rice can be cultivated in volume with modern machinery or in small plots by hand in the traditional fashion, but with either way, the same two basic techniques are used. You can think of them as wet cultivation and dry cultivation.

Wet Cultivation of Rice

Rice needs lots of water through most of its growing cycle, but in the real world, rain doesn't fall consistently. It's usually more common at certain times of the year, so rice-growing cultures developed the technique of building banks around fields and then flooding them while water is plentiful. The fields act as shallow reservoirs, and the rice can be grown right in the flooded fields.

With this growing method, rice seedlings are usually transplanted into fields containing about 1 1/2 inches of water. As the plants grow taller, the water is deepened gradually up to about 4 inches and then drained about seven to 10 days before harvest. It's also possible to plant the seeds directly in a dry, prepared field and then flood it once the plants are well established. Keeping the rice well watered is the main benefit of wet cultivation, but it also keeps weeds from competing with the rice plants.

Dry Cultivation of Rice

Two methods of dry cultivation of rice are used. The first is "dry" only in the sense that the rice isn't kept growing in water for most of its life cycle. Instead, the fields are flooded periodically, whenever the level of moisture in the soil drops to more than 6 inches below the surface. To guarantee a heavy crop, the fields are kept fully flooded while the rice is flowering and for a week before and a week after it flowers. After that, as the rice grain grows and matures, the fields go back to periodic irrigation when the soil dries out.

There's also a true dry cultivation method, similar to the way other grains are grown. This is called aerobic cultivation to distinguish it from the wet cultivation technique, which keeps the rice underwater and blocks it from the air. Instead of flooding the fields or saturating the soil, irrigation is applied as needed to meet the rice plants' growth requirements, and no more.

Traditional techniques such as covering the soil with mulch to reduce moisture loss can help. The big advantage of aerobic cultivation is that it reduces the rice's need for water, but the corresponding disadvantage is that it needs more fertilizer and pesticides to help it compete with weeds.

Growth of the Rice Plant

However it's cultivated, rice grows in much the same way. It's a large grass, and it resembles a scaled-up version of the grasses you see in any field. As it grows, each stem puts out jointed side stems called tillers. Eventually many — though not all — of these tillers produce what's called a panicle, a sort of bud. The rice plant flowers blossom from each panicle, shedding pollen on each other and fertilizing the grain. The grain can be fully mature in as few in 15 days in tropical growing regions, or, in cooler areas, it might take as long as 65 days.

Milling the Rice

The mature grain can be harvested by large machines or by hand with a blade, but once it has been cut, the grains must be separated from their stems and milled to remove the inedible outer husk. If the husk is removed but the bran layer is left in place, the result is brown rice. If the grain is milled further, removing the bran layer and the embryo or germ, what's left is polished white rice.

Sometimes, the rice is steamed or par-cooked while it's still in the bran, then cooled and dried again. This process infuses the grain itself with some of the nutrients from the bran and germ, which are then milled away to leave a more nutritious grain than plain white rice. This parboiled or "converted" rice may sound like an industrial product, but it's actually been performed at the village level for centuries.

Brown vs. White Rice

Brown rice is a whole grain product, which means it contains every part of the rice seed structure, even if it's processed into a breakfast cereal or a snack product. The bran and germ contain much of rice's fiber, oil and vitamins, so nutritionally, that's a good thing.

Unfortunately, the grain's oils spoil a lot more easily than its starch, especially in the hot climates where most rice is grown. That improved shelf life is one reason why most growing regions prefer to cultivate white rice instead of brown. A second reason is that white rice cooks more quickly, which is important in areas where fuel for cooking is costly.

Unfortunately, if you rely on white rice for too high a percentage of your calories and can't afford other foods to balance it, this can lead to malnutrition in a number of forms. One common example is a lack of thiamine, also known as vitamin B1. A diet low in thiamine can result in an illness commonly known as beriberi, which historically has killed and crippled poor people in large numbers throughout the rice-growing regions.

Colored Rices

Some whole-grain rices aren't the usual plain and dowdy brown. Instead, they boast vivid hues of red, purple and black. Those colors are created by pigments called anthocyanins in the bran layer of the grain. They're the same compounds that give dark grapes and blueberries their color, and they're known to have powerful antioxidant effects. That said, colored rices are mostly valued for their visual appeal and nutty flavor rather than their added nutrition.

The marshy Camargue region in southern France grows a distinctive red rice, as do Thailand and the tiny kingdom of Bhutan in the Himalayas. Black and purple rices are grown in Japan and other parts of Asia, as well as in the Po Valley in Italy. These pigments are all water soluble, so they'll give your finished rice dish a deep red, black or purple color.

Two Kinds of Rice

Two species of rice are grown commercially. One is Oryza glaberrima, which is grown in West Africa. The other, and more important, is Oryza sativa. Unless you live in an area with a large African population, chances are you've only ever seen O. sativa at your local supermarket. There are two subtypes of O. sativa, called indica and Japonica, which account for the whole variety of rices that line supermarket shelves.

Indica varieties make up the long grain rices, including fragrant Indian or Pakistani basmati and Thai jasmine rice. Japonicas comprise the shorter and stickier rice varieties used in many other Asian cuisines, as well as the Italian rices used in risotto and the Spanish rices used for paella.

Aside from the commercial varieties, there are hundreds of species growing wild around the world. These wild rices represent a level of genetic diversity that scientists see as a crucial resource, a kind of "life insurance policy" for the commercial varieties of rice. If disease, parasites or climate change should threaten the world's rice crops, hybrids or genetic material drawn from the wild rices could prevent widespread famine.

Wild Rice Isn't Rice

It's important to note that the wild rice you see in supermarkets isn't the same kind of wild rice that acts as a natural seed bank for commercial rice production. The long, dark grains of "wild rice" you see in your supermarket, grown originally in a stretch of wetlands along the Midwest and Canada's southern border, are an entirely different plant.

There are two commonly grown and closely related species, Zizania aquatica and Zizania palustris, that account for most production. There's a third variety in Texas and another in Asia, but they're not important in the overall North American market. Z. aquatica and Z. palustris love water just as much as true rice, growing naturally in the mud at the edges of lakes, marshes and slow-moving streams. These long, dark kernels are cooked in much the same way as rice, but have a distinctively bolder flavor that pairs well with game and other full-flavored entrees.

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