Rice is a staple crop globally, and the term “seed” commonly refers to the harvested grain used for both consumption and planting. The grain’s appearance changes dramatically depending on whether it is still protected or has undergone processing. This transformation involves removing several outer layers, revealing different anatomical structures. The visual characteristics of the rice grain are highly dependent on its stage of preparation.
The Seed in its Natural State (Paddy Rice)
The rice grain immediately after harvest is known as paddy rice or rough rice, which is the actual seed of the plant. The edible kernel is fully encased in a tough, inedible protective layer called the hull or husk. The hull is rigid, rough, and abrasive due to a high silica content, providing defense against pests and environmental damage.
Paddy rice color varies but generally appears in shades of yellow, tan, or light brown. The husk is formed from two tightly interlocked parts, the lemma and the palea, which completely enclose the inner kernel. This rough, unhulled form is used for sowing, as the husk shields the delicate components necessary for germination.
Internal Structure of the Rice Grain
Once the tough outer hull is removed, the remaining structure is known as brown rice, revealing the kernel and its layered anatomy. The outermost layer is the bran, a brownish layer surrounding the starchy center. This bran layer, which includes the pericarp and aleurone, gives brown rice its characteristic color and is rich in fiber and nutrients.
The germ, or embryo, is located at one end of the kernel and possesses the ability to sprout into a new plant. The largest component is the endosperm, the main starchy body that constitutes about 70% of the grain’s weight. The endosperm appears opaque white and is packed with starch granules, serving as the energy reserve for the seed.
How Processing Changes Appearance
The transformation from brown rice to common white rice involves milling or whitening, which significantly alters the grain’s appearance. This mechanical process removes the outer bran layer and the germ from the kernel. As the bran layer is peeled off, the brown or tan color disappears, and the white endosperm is fully exposed.
The resulting white rice kernel has a smoother, shinier, and more polished look compared to the rougher texture of brown rice. This polishing stage increases the grain’s whiteness value and can make the surface appear translucent. The removal of the outer layers causes a slight reduction in the grain’s overall size and a change in shape, often leaving a small indentation where the germ was located.