Composition:- The structure of cereals grains is similar in that they are all a nut-like fruit containing only one seed. The embryo occupies only a small portion of the seed, the bulk of it taken up by the floury portion, or endosperm, which makes up the food reservoir. The outer covering, or bran layers, are high in protein, cellulose, hemicelluloses and mineral constituents while the endosperm consists largely of starch granules embedded in a matrix of protein. The germ is rich in protein, lipids, sugar (chiefly sucrose) and in ash constituents.
Nutritive Value:- cereals are the most concentrated and cheapest sources of food energy known. Though their chemical composition varies widely due to varietals, soil and climatic factors, they are characterized by their relatively low protein content and high nitrogen-free extract of which 90 percent or more is starch. The protein content of cereals is an important index of quality for certain types of food products but, as a class, cereal proteins are not so high in biological value as those of certain legumes or animal products. Wheat and corn proteins, for example, are lacking in the essential amino acids, lysine and tryptophan. However, the normal American diet at present includes sufficient animal products to effectively supplement the cereal proteins and cereals are important and valuable sources of amino acids for the building of body proteins.
Cereals are generally low in the nutritionally important element calcium and its concentration along with other ash and vitamin constituents is reduced by the refinements of million processes. Methods of enrichments have been developed, however, which maintain or even increase the nutritional value of the cereal grains in their processed products.
Enrichment. “ Enriched’ is the term chosen by government and industry in 1941 to describe the characteristics of foods which have been improved through the addition of nutrients for the purpose of fulfilling the nutritional needs of the mass of population. Enrichment of cereal foods on a large scale began in 1941 with the addition of a finely powdered mixture of thiamine, niacin and iron to wheat flour during the milling process. Riboflavin was including in 1943. Since 1941, Public Hearings have been called by the Food and Drug Administration to consider enrichment of a number of staple foods, and Standards have since been established. The magnitude of the enrichment program in the United States is emphasized by the fact that, in 1950-53, sufficient ingredients were sold to enrich from 77 to 81 percent of the total amount of flour sold for family use or for commercially baked bread, rolls and buns for civilian consumption. Many countries, including Canada, Sweden, Denmark, England, Chile, Brazil, and others permit, require, or are about to enact laws requiring some type of enrichment of white flour.
Harvesting and Storage. In addition to high yields and good adaptability, ease of cultivation has helped develop the importance of cereal crops. Sowing and reaping operations have been mechanized to a point where a large area sown and the grain are harvested quickly and efficiently by use of such machines as the self-propelled combined harvesters. Worldwide use of cereal grains for food has resulted in part from the ease with which they can be stored. Under ideal conditions, grains that is sound and dry can be kept for several years without loss of quality, and even under poor conditions grains can usually be stored for several months and still be fit for food.
Insects are a greater problem in hot countries than in more temperature climates, especially when grain is stored in sacks. Fumigation with mixtures of ethylene dichloride and carbon tetrachloride, with methyl bromide, and with fumigants of other types, is widely practiced. Systematic fumigation every few weeks, and use of dusts to inhibit reinfestation, is often required for sacked grain stored in hot climates. Bulk storage can generally be made relatively insect-proof, facilities fumigation, and also reduces the surface presented to insect that do not penetrate deeply.
The type of storage selected depends on amount of grain, storage time, need for maintaining quality (e.g, requirements of enforced government grading), need for improving quality (by drying, cleaning, or mixing), on frequency and speed requirements in filling and emptying and on general economics. Economics are generally paramount. No generalization can be offered; a home-made clay vessel with lid, and plugged outlet at bottom, holding 5 bushels, in a hut in India, may be as sound as solution of a practical problem as a million bushels, concrete elevator, in some city in the United States.
With this general background, each of the cereal grains will be considered individually with respect to the current status of production, processing and utilization. Especially types of cereals products will then be discussed followed by a summary of non-food uses for cereals and cereal products.