Rice is the one of the most consumed grains in the world, second only to wheat, according to John Griffith Vaughan and Catherine Geissler’s book “The New Oxford Book of Food Plants.” Oryza sativa and Oryza glaberrima are the most common species of the grain, which is primary cultivated in Asia, though there are other agricultural sites in the rest of the world. Each grain of rice is comprised of many components, from the hull to the germ.
When rice is first harvested, it has a tough protective husk known as the hull. This outer shell has two components: the outer part of the hull, “lemma,” and the inner segment of the shell, “palea.” The lemma covers two-thirds of the seed, while the palea is the lining that hugs the seed. The hull is indigestible, due to the opaline silica, which is a hydrated form of silica, and lignin, a complex component that helps to hydrate the rice grain.
The bottom part of the rice brain is called the rudimentary glume, and it attaches the grain to the hull. In the flowering stage, this part of the plant is called the “spikelet,” and can hold one or more flowers. Once the flowering stage passes, and the plant starts growing the rice, these glumes reduce to being the connector between the grain and the stem. Both the hull and the glume are the first to be discarded during the shucking process.
Once the hull is removed, the rice grain becomes brown rice, which is the seed plus the bran layer. The bran layer is edible and is very nutritious, containing high levels of antioxidants. Other nutrients include high levels of protein, iron and the vitamin Bs. Rice bran is also noted for its fiber, as it can be used to enrich breakfast cereals and breads. Once this layer is discarded, the final milled white rice grain is less nutritious.
The rice’s seed is comprised of the embryo and endosperm. The embryo, also known as the germ, is the reproductive part of the rice. It is the bottom part of the rice seed, which is necessary to be removed to produce the final milled white rice. The endosperm is the actual part labeled white rice. Furthermore, once the grain is produced into to white rice, it makes up less than 10 percent of the entire rice grain’s weight.