Barley a minor cereal

Cereals are the edible seeds or grains of the grass family, Gramineae. A number of cereals are grown in different countries, including rye, oats, barley, maize, triticale, millet and sorghum.

Barley (Hordeum vulgare L.), originally from the Middle East, was one of the first plants domesticated for human consumption and was known for its vast geographical distribution. Barley has many uses, for instance it can be served as animal fodder, as base malt for beer and certain distilled beverages, and as a component of various health foods. It is used in soups and stews, and in barley bread of various cultures.

Pearled barley is eaten in soups and stews in the UK and in the Far and Middle East; barley is also used in bread (as flour) and ground as porridge in some countries.

The major parts of the barley grain are the endosperm, the embryo and their covering layers of maternal origin. The endosperm consists of the starchy endosperm and a surrounding aleurone layer (Figure 2). The starchy endosperm forms the largest morphological part of the barley grain comprising c. 75% of its weight. The function of the starchy endosperm is to serve as a nutrient storage for the growing embryo during germination.

Barley is characterized by a thick fibrous coat, a high level of ß-glucans and simply-arranged starch granules. World production of barley is about 30 % of that of corn. In comparison with corn, barley has more protein, methionine, lysine, cysteine and tryptophan.

Barley grain is an excellent source of soluble and insoluble dietary fiber (DF) and other bioactive constituents, such as vitamin E (including toco-tri-enols), B-complex vitamins, minerals and phenolic compounds.

Barley is also a rich source of tocols, including tocophenols and toco-tri-enols. Barley contains3-11% dietary fibers made up of pentosans, beta-glucan and cellulose. Barley has an attractive nutrient make-up which makes it an excellent food for health-conscious people.
Barley a minor cereal

Wheat grain morphology

Wheat grains, botanically, are the fruits (caryopsis) of the wheat plant. Mature wheat grain or kernel is roughly ovate or egg shaped. Wheat structure is a single seeded fruit, 4 to 10 mm long, consisting of three main parts namely the bran, the endosperm and the germ or embryo.

The fruit coat or pericarp (45 to 50 um thick) surrounds the seed and adhere closely to the seed coat.

Wheat grains are bone on a spike, also called an ear, which is a branched structure. The major axis of this spike bears two rows of alternating secondary axes known as rachillas.

The wheat color, depending on the species and other factors is red to white and is due to material present in the seed coat.

Wheat also is classified based on physical characterizes such as red, white soft, hard spring or winter.

Wheat kernel cross section

The grain obtained from the wheat plant is a nut-like fruit called by botanist a caryopsis. It includes a single seed or kernel enclosed within a thin shell derived from the ovary wall of the maternal parent.

The outer pericarp is consisting of the epidermis and hypodermis. The epidermis consists of a single layer of cells that from the outer surface of the kernel.

On the outer walls of the epidermal cells is the water impervious cuticle. Some epidermal cells at the apex of the kernel are modified to form hairs.

The hypodermis is composed of one to two layers of cells. The inner pericarp is composed of intermediate cells and cross –cells inward from hypodermis.

Long and cylindrical tube cells constitute the inner epidermis of the pericarp. A deep groove or crease extends the entire length of the wheat kernel. It cuts almost to the center of the kernel. In the crease, the seed coat joins the pigment strand, and together they form a complete coat about the endosperm and germ.

Three layers can be distinguished in the seed coat: a thick outer cuticle, a “color layer” that contains pigment, and a very thin inner cuticle.

The bran comprises all outer structures of the kernel inward to, and including the aleurone layer. The aleurone, which forms the outer periphery of the endosperm and the innermost layer of the bran, accounts for 3%-4% of the weight of the kernel; it is usually removed with the bran during milling.

The endosperm is composed of peripheral, prismatic and central cells that are different in shape, size and position within the kernel.

The endosperm cells are packed with starch granules, which lie embedded in a protein matrix. Wheat endosperm contains mainly to types of granules a larger type, mostly about 20-35 micrometers (um) across (A-starch), being lenticular in shape, and a smaller spherical type, ranging from 2-8um in diameter (B-starch).
Wheat grain morphology

The structure of corn

The corn kernel is not merely a seed but as one seeded fruit. The kernel consists of the pericarp or skin, germ or embryo and the endosperm.

Corn grain is composed of endosperm (82-83%), germ (10-11%), pericarp (5-6%) and tip cap (0.8-1.0%).

The pericarp is the outmost layer that is characterized by high crude fiber content, mainly consisting of hemicellulose, cellulose and lignin. The pericarp protects the kernel and resists penetration by water. Endosperm contains approximately 87-88% of starch that consists of amylose and amylopectin.

The endosperm consists of a thin layer of aleurone cells containing oil an protein and a large inner portion of storage tissues containing starch and protein.

The germ is high in oil, protein, sugars, vitamins and minerals with little starch.

The aleurone is a single layer of cells in the pericarp that contain a larger proportion of oil, protein, minerals, ash, vitamins and enzymes that other cells.
The structure of corn