Food study main foods – cereal grains
WEEK 1
DATE:___________
SUBJECT: FOOD AND NUTRITION
TOPIC: food study; main foods – cereal grains
CONTENT:
i. Types of cereal grains
ii. Nutritive value of cereal grains
iii. Processing of cereal grains
SUBTOPIC 1: types of cereal grains
Cereals are the edible seeds of the grass family e.g. rice, corn, guinea corn, millet, wheat etc. The chief food nutrient of cereal is carbohydrate (starch). They therefore belong to the energy food group. They contain protein and the B vitamins which are found in the germ or embryo and in the outer part of the grains.
Meaning and definition of cereals grain
Cereal is the broad term used for the plants belonging to the grass family. The seed they produce are known as grains. They are a very important class of food to mankind throughout the whole world. Animals and birds depend on cereal grains for their food. Cereals form the staple food in many countries of the world. Some of the common grains are: rice, maize, guinea corn, millet, wheat, oats, rye, sorghum etc.
SUBTOPIC
1: types of cereal grains
Some of the common types of cereal grains include:
(a) Maize: maize is one of the most important grain crops in the world. It is a tall cereal plant which contains the corn kernel. The different varieties of maize are: dent corn or fried corn, flour corn, pop corn, flint corn and sweet corn. Maize has a lower nutritional value than wheat and is deficient in vitamins.
(b) Rice: rice is such an important part of the diet of world’s population. About 50% of the intake of calories is provided by it. It is grown in the river deltas or riverine areas, flooded or irrigated coastal plains, terraced hill side, it can also be grown in many climactic conditions, but it is most often cultivated in sub-tropic and temperate regions. Rice varieties are available in both white and brown forms.
(c) Wheat: in addition to rice and corn, wheat is one of the three most important grain groups in the world. Unlike some grains, especially corn, most of the wheat that is cultivated is used as food for humans. Most wheat is grown in temperate climates, with a large proportion grown in the great plain region of the United States and other parts of the world. Wheat is classified into hard and soft wheat.
(d) Sorghum: sorghum is a cereal plant that is native to Africa, but it is also cultivated in many parts of the world. Sorghum grows in a variety of climates and in a hot arid location. The grain ranges in colour from white to red depending on the variety of sorghum grown. Sorghum grain has a sweet flavour that is delicious when steamed or added to soup. It is used as a staple food crop in Africa.
(e) Millet: millet is a variety of related plants because small seeds. It is an important food crop in some of the hot, arid national of Africa. Millet has a mild sweetness and crunchy texture and is eaten as a cereal – a side dish and an addition to soup, stews and as desserts. The seeds are good if roasted when they are fresh.
(f) Barley: barley is a member of grass family. It is a major cereal grain. Other cereals include buckwheat.
SUBTOPIC 2: Nutritive Value of Cereal Grains
Nutritive Value of Cereal Grains
Like all seeds, cereals are very nutritive because they contain vital nutrients. Unrefined cereals are valuable sources of proteins, carbohydrate, and vitamin B and also contain some fat, iron, vitamin E and trace minerals. They are very good sources of fibre in the diet. The proteins in cereals are incomplete like other vegetable proteins which lack one or more essential amino acids. They are well utilized when they are supplemented by more complete proteins of fish, meat, milk and legumes like soya beans.
Most of the food energy in cereal grains comes from carbohydrates. The fat content of wheat cereal is greater than that of refined cereals. The mineral and vitamin in cereals are low and are found in the aleurone, germ and scutellum layers. However, yellow maize is richer in carotene. The protein in wheat is called gluten.
SUBTOPIC 3: Processing, uses and choice of cereal grains
Processing cereal into flour
Cereal grains can be in the form of a whole cereal with no part of the layers removed and the refined form with almost all the layers of the grains removed. The refined form of processing through the machine is called milling. Machine milling affects the nutritional value of the refined cereals where the layers containing the important nutrients such as the vitamins, proteins, iron, etc are removed leaving only the endosperm which contain only starch. Cereals that go through these processes are maize, sorghum (guinea corn), millet, wheat, rice etc.
Rice can be milled brown or polished. The brown rice is that which the bran and other layers are retained while polished rice is that which almost all the layers have been removed.
During the milling process, the husk is removed followed by the aleurone, the scutellum and the germ layers. When only the husk is removed, the resulting rice is called brown rice which still has the aleurone, scutellum and germ layers. However, when milling is continued to remove these layers, the resulting rice is called colour rice. Such rice is whiter than the brown rice since all the layers have been removed; the vitamins and minerals are lost.
a. Wheat is usually milled into flour before it is prepared into food. The proportion of the wholegrain that is used to make flour is known as the extraction rate. The flour that is produced from cereals in which all the layers have been removed is called low extraction rate. However, the milled flour that still retains some of the outer layer is called high extraction rate flour. The high extraction flour is not as white as the low extraction flour but is more nutritive. When whole cereal is cleaned and ground, unrefined flour is produced. But whole cereal cleaned and milled flour is produced as shown in table below.
Cleaned and ground
Cleaning/milling
PROCESSING CEREAL GRAINS
Objective Test
1. What is the collective name for wheat, rice, maize, millet and oat?
(a) Fruits (b) seeds (c) cereal grains (d) legumes
2. The name for wheat protein is called ________. (a) gluten (b) myosin (c) zein (d) gluten
3. The preparation of the wheat grain that is utilized to make flour is called _______. (a) high extraction (b) low extraction (c) extraction rate (d) Low extraction rate flour is produced from flour that has been. (a) blended (b) unrefined (c) refined (d)washed
4. Which of the following is not a cereal? (a) maize (b) barley (c) millet (d) guinea corn
5. Dried cereals best stored in ………… (a) box (b) cupboard (c) refrigerator (d) silos
6. Cereal grains can be processed into. (a) powdered food (b) liquid food (c) solid (d) flour (e) mixtures of food
7. The refined form of processing through the machine is called ______. (a) grinding, (b) sieving (c) milling (e) draining
8. The starch in the cereal grains are store in the ______. (a) bran (b) aleurone layer (c) endosperm (d) scutellum
9. Rice can be milled _______ and _______. (a) yellow or grey (b) painted or plain (c) white or black (d) brown or polished (e) short and long
10. During the milling process, when only the husk is removed, the resulting rice is called _________. (a) cleaned rice (b) sieved rice (c) brown rice (d) mix rice (e) safe rice.
Evaluation:
1. Describe the process of obtaining flour from cereal grains
2. Explain at least two (2) effects of milling on the nutritional value of cereal grains.
3. Differentiate between brown rice and polished rice.
4. Identify different cereal grains
5. Write the importance of cereal for man and animals
6. List 3 conditions for cultivating cereals.
7. Write five (5) staple foods in Africa
8. Discuss the nutritive value of cereal grains.
9. Explain where minerals and vitamins are found in cereals
10. With the help of a diagram, explain the two (2) processing methods to obtain wheat flours.
ACTIVITY: Students should list the various types of cereal grains used for food in their locality and describe how they are prepared.
Weekend Assignment
Read Evans food and nutrition for senior secondary schools book 2 by F. A, Bakare et al. Page (1-9)
Pre-reading assignment
Read on the uses and choice of cereal grains and cooking methods.
Reference Texts
– Evans food and nutrition for senior secondary schools book2 by F.A. Bajare et al; Evans Brothers Nigeria Limited.
-Food and nutrition for senior secondary school. Page 1-3 by J.O Olusanya et al (page 58 –60).
FOOD AND NUTRITION SS2 FIRST TERM