Cereals - Structure & Components PDF

**CEREALS** Cereal grains are the fruit of plants belonging to the grass family (*Gramineae*). India is the world\'s second-largest producer of Rice, Wheat and other cereals. The important cereals are - wheat, paddy, sorghum, millet (Bajra), barley and maize, etc.  - RICE - Oryza sativa -...

**CEREALS** Cereal grains are the fruit of plants belonging to the grass family (*Gramineae*). India is the world\'s second-largest producer of Rice, Wheat and other cereals. The important cereals are - wheat, paddy, sorghum, millet (Bajra), barley and maize, etc.  - RICE - Oryza sativa - Staple food - 3 races: Indica, Javonica & Sinica (Japonica) - WHEAT - Triticum aestivum, Triticum durum - CORN - Zea mays - BARLEY -- Hardeum vulgare - Gladiators were known as hordearii, means eaters of barley - Barley -- king of grains **STRUCTURE OF CEREAL GRAINS** - Cereal grains -- dry fruit called caryopsis; plant seeds - 3 distinct structure endosperm, hull & bran, embryo / germ Cereal grains are the fruits of the grass family of plants. The grain develops from flowers or florets which are enclosed in a pair of bracts or leaves, called lemma and palea. +-----------------------------------+-----------------------------------+ | **Caryopsis/ naked grains** | **Covered or coated caryopsis** | +===================================+===================================+ | The lemma and palea become free | The lemma and palea adhere to the | | from the grain at threshing and | grain and do not come away during | | form chaff. | threshing. | +-----------------------------------+-----------------------------------+ | Eg: Wheat, rye, common varities | Eg: Rice, oats, some varieties of | | of maize, some varieties of | barley, and Sorghum. | | sorghum and barley. | | +-----------------------------------+-----------------------------------+ | Consist of fruit coat (pericarp) | Consist of fruit coat (pericarp) | | and seed. The seed comprises the | and seed. The seed comprises the | | seed coat, germ and endosperm. | seed coat, germ and endosperm. In | | | addition, fused palea and lemma | | | which constitute the husk outside | | | the | | | | | | fruit coat. | +-----------------------------------+-----------------------------------+ Rice grains resemble wheat but is smaller than that of wheat. It is flattened laterally and has no ventral furrow. Most cereal grains have four major components: the **hull or husk, the bran layer, the endosperm, and the embryo or germ.** **BRAN:** - - - - Bran is the outer coating or shell on grain that is removed while processing white flour. Bran consists of the **[[pericarp],](https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/pericarp) the seed coat, and the [[aleurone layer]](https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/aleurone-layer)**. The pericarp itself consists of three layers of differentiated types of cells Pericarp: ========= The pericarp, which lies in the outermost layers of the caryopsis, is composed of three layers, namely, the epicarp, mesocarp, and endocarp. - **Epidermis / Epicarp** The outer layer of the cereals consist of thin walled, long, rectangular cells. - **Mesocarp / Hypoderms** Next to the epidermis is the hypoderm of varying thickness. - **Endocarp** The innermost layer of the pericarp tears during the ripening of the seed and in the mature grain they are represented by a layer of branching hypha-like cells known as \"tube cells.\" Seed coat: ========== The seed coat or testa is a thin single or double layer, with the cellular structure almost obliterated. The seedcoat consists of an epidermis (outer layer) and several inner layers. Next to the testa is the hyaline layer (mucellar layer), which is colourless and devoid of any obvious cellular structure. Aleurone layer ============== The endosperm is surrounded by one or more layers of cells known as aleurone. The aleurone layers generally surround only the starchy endosperm and cease where the latter abuts on the scutellum. Endosperm: ========== The endosperm itself consists of cells of various sizes, shapes and different compositions. The endosperm cells consist mainly of **starch and protein**, the starch being in the form of **spherical granules** which are single granules or tightly packed together, and embedded in a matrix of protein. Embryo: ======= The germ or embryo consists of many parts. It is separated from the endosperm by the **scutellum,** which has the function of mobilizing the stored food reserves in the endosperm and transmitting them to the embryo, when the grain germinates. The germ and scutellum are rich in **protein and fat**, while most of the **B vitamins** in the grain are present in the scutellum. -- -- -- -- -- -- -- -- +-----------------------------------+-----------------------------------+ | Varieties of rice are classified |  | | according to kernel weight, | | | length and breadth. Based on | | | ratio of the length to the | | | breadth, the grains are described | | | as slender, medium or bold. | | | | | | --------------- -- -- | | | Long slender | | | | | | Media slender | | | Short slender | | | | | | --------------- -- -- | | | | | |  | | +-----------------------------------+-----------------------------------+