John K. Saichuk | 3/24/2005 4:10:18 AM
The mature rice kernel or grain is made up of several parts. The outer protective structures are called the hulls. The hulls are made up of two parts; the outer is called the lemma and the inner is the palea. The small structures labeled "glumes" are rudimentary structures sometimes called bracts instead of glumes. This unit is referred to as a spikelet before grain formation. By definition a spikelet consists of two glumes and one or more florets. In rice there is a single floret represented here by the lemma, palea and grain. Because rice has no well-developed glumes, the spikelet and floret are basically the same unit.
The first step in milling rice is to remove the hulls - the lemma, palea and glumes. The hulls make up about 20% of the rough rice weight. Rice in this form is called brown rice. After the hulls are removed, the bran layers are removed, producing the familiar milled white rice. In this step the area labeled "embryo" is also removed. The bran, embryo and other miscellaneous by-products make up about 10% of the original rough rice weight.
The embryo is also called the "germ" because it is the part of the seed that germinates or produces a new plant if the seed is planted rather than milled for consumption. The endosperm is mostly carbohydrates. Because of the oils and other compounds associated with the embryo, brown rice cannot be stored as long as milled rice.
The LSU AgCenter and the LSU College of Agriculture