CEREALS

INTRODUCTION Cereal grains are seeds of cultivated grass. They are probably the most important commodities forming the bulk of the diet in many developing countries either as food for human or indirect food of animals The most important cereals are:- a) Wheat b) Rice c) Oats d) Rye e) Maize f) Barley In Europe and North America Australia and some part of Asia, wheat is most significant crop where as part of Asia, the Far East, West Africa and some Latin America countries is replaced by rice and in America and Africa by maize WHEAT It is a grain consisting of a tough fibrous coat which protects the germ/embryo and food reserves found inside. Figure I

Husk (bran)

Aleurone Embryo layer contains B1

Endosperm and vitamins Embryo Aleurone layer contain minerals and vitamins

When wheat grain germinates the germ develops into a new plant using a food reserves in endosperm, aleurone layer and germ itself. The bulk of food reserves are found in endosperm which contains large amount of starch as well as protein and BS` vitamin The aleurone and germ are rich in B vitamins and also contains protein Different varieties of wheat are produce different types of flours because of protein concentrate The most important protein in wheat is ``gluten ‘which usually contain two proteins i.e. glutenin and gliadin Gluten is important in dough formation and varies from 11 to 15 % in hard wheat.canadian and North America to 8 to10% Durum wheat has gluten content of 11-13% and is used for manufacture of spaghetti and other pastas and macaroni.

RICE The structure of a grain of rice is very similar to that of wheat grain. It consists of a hard outer coat which is usually removed. Rice grow well in wet tropical climate and it is a very important crop in many parts of the world particularly in Asia Since the milling process removes the bran and germ, large amount of thiamine are lost and this can because deficiency disease called beriberi. Infact beriberi is not uncommon in many part of Asians but in occurrence should reduced if the rice is par-boiled (soaked and steamed) because much of thiamin is stored in endosperm Brown rice consist of wholegrain rice from which only the outer most layer has been removed MAIZE Maize or corn has quite different structure of wheat or rice. It can be eaten as corn-on the cob or when to produce corn oil, cornflour, breakfast cereals such as cornflakes and wetabix Maize is considered to the slightly less nutritious than other cereals because it has fewer vitamins B1

OATS, RYE AND BARLEY Oat grain contain more protein and fat than other cereal grain and used extensively for animal and human consumption The oat grains are often rolled into flakes and used to produce muesli, biscuit, porridge and others Rye is cereal with a low gluten content which grow on poor soils It can be milled like wheat and is often combined with wheat to make breads as well as being used to manufacture whisky Barley is another resilient cereal which is used in brewing and distilling as well as for animal food The husk can be removed to produce pearl barley which is used in some soups and stews

A COMPARISON OF THE NUTRITIONAL CONTENT OF CEREALS IS GIVEN BELOW Table 2.nutritional content of various cereals per 100g protein fat carbo Vit/m water fibre wheat 12 2 70 2 12 2 maize 11 4 69 2 12 2 Rice 7 1 77 2 12 1 Oats 11 9 66 2 10 2 Barley 8 1 75 2 12 2 Rye 8 2 72 2 15 1

FLOUR Most of cereals that have been considered in this chapter are processed in order to make it more palatable Perhaps the most obvious of this in western world is conversion of wheat into flour and then bread The manufacture of flour from wheat is a detailed process and includes the following stages 1. CLEANING:-the wheat grains are cleaned to separate them from stones soils and other waste that were gotten from the shamba when harvesting as well as when transporting 2. CONDITIONING:-this produces the collect moisture level for grain for ``breaking’ it. 3. A series of break rollers are used with successful small gap to be separate from the bran with increasing sufficiently

BREAKROLLER ////////////// wheat grain // //////// slow ///// Revolving break Rollers moving Fast

///////// ////// flour produced They are series of break rollers with tips to reduce the particles in fine flour 4. REDUCTION:-smooth rollers reduce the particles to a fine flour EXTRACTION RATE Wheat is processed in various types of flour which are graded according to how much the grain they contain TABLE 1 MAIN TYPES OF FLOUR FLOUR PARTS OF GRAIN EXRACTION RATE INCLUDED IN 100G Whole meal Whole grain- 100% endosperm, germ and bran Wheat meal Endosperm, germ 80-95% and some bran(outer layer are removed) Wheat germ Endosperm and 85% germ, to which extra germ has been added White flour Endosperm(germ 72-75% and bran are removed patent endosperm 40-45%

In flour of low extraction rate there is requirement by law to enrich them with thiamine, nicotinic acid, iron, calcium These vitamins and minerals are lost during the milling process as germ and bran are removed EFFECTS OF COOKING AND USE OF FLOUR FLOUR:-the two main component flour that is affected by cooking and gives flour its properties are starch and gluten The role of flour is to make:- 1. Sauces e.g. roux 2. Creamed sauces coagulation of gluten during cooking is another important property of flour and indeed flours are selected for their gluten content e.g. in bread making a high gluten is required to give a strong elastic network capable of holding gas produced by yeast which give bread a good structure Conversely in products which do not require gluten development such as short cake, light cake, short crust pastry, biscuits, flour with lower gluten are desirable TABLE 2: SOME OF USES OF DIFFERENT TYPES OF FLOUR FLOUR USES Whole meal Bread and biscuits Wheat meal Bread and biscuits White strong Bread,pudding,pastries soft Light cakes and biscuits Self raising Some cakes, corns which require some raising agent Starch reduced Bread with reduced energy patented Bisquits,short bread and cakes durum such as spaghetti,macoroni,noodles

ORDINARY BREAD FAULTS AND THEIR CAUSES

Poor Less Much Dough Less Dough Dough Dough Dough mixing salt salt weighed yeast proved under temperature temperature much too proved Too high Too low much Lack volume x x x x x Too much x x volume Crust colour x pale Crust colour x too dark Crust with blisters Shelling top x x of crust Poor texture x x crumby