Maharashtra Board Class 5 EVS Part I Chapter 19 Constituents of Food PDF Download

19. Constituents of Food

Can you recall?

What is meant by diet? For what purposes do we need food? What are the different tastes that foodstuffs have? How do we experience these tastes?

You have learnt that foodstuffs have constituents that are useful to us in different ways. Let us learn some more about the constituents of food.

Carbohydrates

Try this.

Materials: A piece of a potato, tincture of iodine, a dropper.

Procedure: Add some water to a tincture of iodine to dilute it. Using a dropper, put a few drops of it on the piece of potato and observe.

What do you see?

The piece of potato turns a blackish blue.

Starch: Starch turns blackish blue when it comes in contact with iodine. So we can infer that there is starch in the potato. Sago and sweet potato also contain starch. Cereals like jowar, bajra, wheat, rice contain a lot of starch. We obtain flour from these grains. These grains form our staple diet. We get energy from starchy foods. Our body uses this energy for different kinds of work. This energy also keeps the body suitably warm.

Teacher's Note

Starch is found in many foods we eat every day in India like rice, wheat, and potatoes. You can test it with iodine like we did in the experiment.

Exam Trick

Remember: Starch turns blue-black with iodine. This is how you can find starch in any food quickly in the exam.

Points to Remember

Starch is a type of carbohydrate found in grains and potatoes.
Iodine turns starch blue-black in color.
Starch gives us energy for work and keeps us warm.
Jowar, bajra, wheat, and rice are main sources of starch.

Do you know?

When the starchy foods we eat are digested, sugars are formed. These sugars burn slowly in our body, releasing energy. In other words, sugars formed by the digestion of starch act as fuel for our body.

Use your brain power!

Why do we feel hungrier in winter than we do in summer?

Can you tell?

(1) What substances do we use to give our food a sweet taste?

Try this.

Materials: A fine sieve, some whole wheat flour.

Procedure: Sift the flour.

What do you see?

Most of the flour falls through the sieve. But some larger particles are left on the sieve.

Fibre: When grain like jowar, wheat is ground into a flour, the particles in the flour are not all alike. When the flour is sifted, we find the larger particles left behind on the sieve. These particles are fine pieces of the skin or bran of the grain.

Bran is a fibrous substance. In the process of digestion, fibre has a special function. Fibrous substances help the food to move forward in the alimentary canal at the right speed. The undigested food is of no use to the body. Fibre helps to form stool from this undigested food. Fibre is also called 'roughage'.

Sugars: Foodstuffs that taste sweet contain different kinds of sugars. For example, we can obtain jaggery and table sugar from sugarcane because it contains a sugar called sucrose. Ripe fruits like mango, banana, chickoo as also honey and milk also contain various kinds of sugars. They, too, give us energy.

Fruits and vegetables, especially their skins, whole grains and pulses are all sources of fibre in food. If our food does not contain enough fibre, it can lead to constipation.

Up to now we have learnt about three types of substances present in our food - starch, sugar and fibre. These substances are together called carbohydrates. The most important use of carbohydrates is to provide the body with energy.

Teacher's Note

Fibre is found in vegetables like carrots and fruits like apples. It helps our stomach work properly, just like how a broom cleans the house.

Exam Trick

Remember: Fibre = Roughage = helps move food in stomach. Think of fibre like a path that pushes food forward in your belly.

Points to Remember

Fibre is found in skins of fruits and vegetables.
Fibre helps food move through the stomach and intestines.
Fibre helps form stool from leftover food.
Fibre is also called roughage.
Not eating enough fibre causes constipation.

Use your brain power!

Threads get stuck between the teeth when we eat certain types of mangoes. Which kind of carbohydrate are they?

Can you tell?

(2) Of the foods that we eat raw, which ones are sweet?

Fats

Try this.

Materials: Two sheets of white paper, a printed page, a little cooking oil.

Procedure: Rub a little oil on one of the white sheets. Now place the sheets on the printed page, one by one, and try to read the matter through each sheet.

What do you find?

You cannot read the matter through the ordinary sheet, but you can see through the oiled sheet of paper. The oil makes the paper translucent.

Oil is a fatty substance. Paper becomes translucent when a fatty substance is applied to it. Paper becoming translucent is a sign of the presence of fats in the foodstuff kept on it.

Fats in our food also provide energy to our body. They give twice as much energy as carbohydrates. But, we include a smaller quantity of this constituent in our diet. Cream, butter, ghee, oil are examples of fats. Nuts, meat, egg yolk also contain fats.

The fats we eat get stored in our body. If food is not available for some time, the body can get energy from the stored fats.

There is a layer of fat under our skin. It gives shape to the body and like a blanket, also prevents loss of heat from the body.

Teacher's Note

Fats are found in ghee, oil, and butter that we use in cooking at home. Fat gives us more energy than carbohydrates do.

Exam Trick

Remember: Oil makes paper see-through = it has fats. Fats give twice the energy of carbs - so a little goes a long way!

Points to Remember

Fats give us energy and keep us warm.
Fats give twice as much energy as carbohydrates.
Ghee, oil, butter, and nuts have lots of fat.
Fat under the skin protects our bones and organs.
Our body stores fat for use when food is not available.

Can you tell?

Why are boxes of fragile articles like TV, refrigerator, light bulbs, glasses, mirrors packed with corrugated cardboard, thermocol or bubble wrap?

The cardboard, thermocol or bubble wrap protect the fragile articles. Even when the boxes shake, fall or get hit, the articles inside are not damaged. Similarly, the layer of fat in the body protects our internal organs. An injury from outside does not at once cause damage to our bones or other internal organs.

Use your brain power!

Why do we use a padding of cloth under a mortar when we place it on the floor and pound something in it?

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