Rice is primarily classified according to its kernel form and grain shape. However, within the grain shape categories there are differences in cooking qualities. The various grain shape and specialty rice categories are described below.
Rice that has been harvested from the plant with its hull (husk) intact is known as rough or paddy rice. See a description of the rice plant and how it grows at the Rice Knowledge Bank. The hull is not eaten by humans but is sometimes burned for use as an energy source.
When the hull is removed from rough rice it is known as brown rice. However, not all rice with the hull removed is brown in color. The bran and germ that gives brown rice its color can vary from light yellow to red to dark purplish black. Rice bran and germ contains greater amounts of dietary fiber, vitamins, minerals and other health-related components than the white center portion of the kernel (endosperm). But those outer portions of the kernel also contain more lipid (fats) material, making brown rice more susceptible to becoming rancid. It therefore has a shorter shelf life compared to milled white rice. Storage under cool conditions will lengthen its shelf life. Cooked brown rice is chewier in texture than its white rice counterpart and is described as having a slightly nutty flavor.
Rice that has had its bran and hull layers removed by milling is called white, table, and polished or milled rice. White rice cooks faster than brown rice and has a longer shelf life. In the U.S., most white rice is fortified with iron, niacin, thiamin and folic acid.
The category known as long grain contains milled rice that is approximately three times longer than it is wide. A conventional U.S. long grain rice has an intermediate gelatinization temperature, and from 19 to 23% apparent amylose content. After cooking it is firm and fluffy (not sticky). Consumers in areas of the world such as North and South America, Southern China, Europe, and the Middle East often prefer this type of rice. California long grain rice generally has slightly higher apparent amylose content and lower gelatinization temperature compared to southern grown U.S. long grain rice.
The medium grain rice category describes milled rice that is from 2.1 to 2.9 times longer than it is wide. U.S. medium grain rice after cooking is soft, moist and sticky in texture. This type of rice is in general preferred by people from Japan, Northern China and North and South Korea. Medium grain rice is generally lower in amylose content and has a lower gelatinization temperature compared to U.S. conventional long grain rice.
Rice that is less than two times longer than it is wide is classified as short grain. In general short grain rice has cooking quality, amylose content and gelatinization temperature similar to that of rice in the medium grain category. Because this type of rice is used for making sushi some call it sushi rice.
Rice that has cooking or processing quality different from the standard market classes described in the grain shape section above are known as specialty rices. These are used for special styles of cooking and in specific products. Production of these types of rice in the U.S. is much lower than rice that fits the long, medium and short grain market classes.
This rice type originated in Italy where it has traditionally been used for making risotto. Arborio rice is classified as a medium grain, but it has fairly firm internal texture and a unique creamy exterior. It often has a white core (chalky center) that is thought to be responsible for its ability to take up the flavor of the stock or sauce it is cooked in.
Rice of this type has the kernel dimensions of a long grain rice. It has a moderately firm cooked texture, is dry and not sticky after cooking and has an aroma often described as being popcorn like. This category is unique in that its grains become very long and thin (extreme elongation) after cooking. It has an amylose content and gelatinization temperature similar to conventional U.S. long grain rice. Basmati rice originated in India and Pakistan. Today, however, rices that have these same unique quality traits are also grown in the U.S.
Della or Dellmont Quality
This type of rice is a long grain aromatic rice whose aroma is said to be popcorn like. Although the aroma is similar to Jasmine- and Basmati-style rice its texture mimics that of conventional U.S. long grain rice.
Japanese Premium Quality
Japanese Premium Quality rice is similar to conventional U.S. medium grain rice in terms of grain length, amylose content and gelatinization temperature. But it has properties that have been traditionally desired by some people of Japanese and Korean descent. Those properties that make Japanese Premium Quality rice different from standard medium grain rice are said to be its glossiness, lack of flavor, aroma, sticky but smooth texture, and softness after cooling.
This style of rice is originally from Thailand. Much of the Jasmine-style rice sold in the U.S. is imported from Thailand. However, U.S. produced Jasmine-style rice is also available. Jasmine-style rice has long grains that when cooked are soft and cling to each other. It is considered aromatic rice because it possesses a distinctive aroma often reported to be popcorn-like.
Superior Processing Quality (Rexmont or Dixibelle Quality)
Long-grain rice that was developed to remain intact, firm and fluffy after processing into such things as canned soups and frozen dinners is said to have Rexmont or Dixiebelle quality (named after the commercial cultivars that possess this quality). This type of rice also has less solids loss and kernel splitting after processing compared to conventional U.S. long grain rice. It has a similar gelatinization temperature and slightly higher apparent amylose content compared to conventional U.S. long grain rice. But the cooked kernels are firmer and the Rapid Visco-Amylograph hot paste and setback are greater in comparison to conventional U.S. long grain rice.
This is long grain rice that after cooking is soft in texture and the kernels cling to each other. The apparent amylose content and gelatinization temperature of this type of rice is similar to that of conventional U.S. medium grain rice. Toro-Type rice is primarily used in certain ethnic (i.e. Cajun) style cooking.
Waxy (glutinous, sweet or sticky)
This style of rice can be in the long, medium or short grain form, and is eaten both milled and unmilled. Milled waxy rice appears opaque, as opposed to nonwaxy rice, which is translucent. Waxy rice has very little amylose and cooked milled waxy rice is very soft and sticky. When the bran is left on, waxy rice is slightly chewy and flavorful. Flour made from waxy rice is also used in products such as candy, salad dressings, baked crackers, and snack foods. It is an important ceremonial rice used in areas of Asia.
Wild rice is not rice nor is it wild. It is a grass, which is native to North America. It used to be just a natural grass found in shallow lakes and waterways, but it is now grown commercially in the U.S. Its nutty, chewy texture and dark brown to black color provide its appeal.
Rough rice that has been exposed to some combination of soaking in water and exposure to steam, dried, and then milled, is said to have been parboiled or converted. This process results in the natural vitamins and minerals being transferred from the rice bran layer into the starchy endosperm. Parboiling is thought to have originated in India and Pakistan more than 2,000 years ago. It came into use in the U.S. during World War II because it fit the military's need for nutritious food that had a long shelf life. Long grain is the type of rice that is generally parboiled for consumption as table rice. Medium grain rice is also parboiled and ground into flour for use as an ingredient in food products.
Quick cooking and Pre-cooked Rice
Quick cooking brown or white rice has been pre-cooked to reduce its cooking time; its starch may either be partially gelatinized (cooked) or not at all. The process sometimes entails cooking in water or steam and then drying.
White rice that has been ground into a flour or meal is used in many different types of food products around the world. A few examples follow. The relatively bland flavor of rice makes it well suited for use in products with mild flavors. It has advantages over other grains in that it will not obscure what natural flavors are present and less added flavor is needed. Waxy rice is often used to make baked crackers, which are light and crispy. When a firmer less delicate baked cracker is desired medium grain rice is often used. Fried snack foods made using a blend of waxy rice flour and other grains will tend to be crisper and take up less fat than if made without the rice flour. Rice flour made into a cereal is ideal as an initial food for babies because it is hypoallergenic. Being hypoallergenic, plus having the ability to prevent and correct dehydration has resulted in beverage mixes being developed which are rice-based and used in the treatment of diarrheal diseases such as cholera and AIDS.