Chapter 2: Components of Food (Notes)
Posted on : 11-05-2018 Posted by : Admin


As discussed in the previous chapter, people living in different parts of India have different food habits. But to sum it up, our meals have at least one grain along with some vegetarian or non-vegetarian dishes. It may also include items like curd, butter milk and pickles.

All the ingredients we use for preparation of our food dishes are obtained either from plants or animals. These ingredients contain some components that are needed by our body. These components are called nutrients.

The major nutrients in our food are named carbohydrates, proteins, fats, vitamins and minerals. Also our food contains dietary fibers and water which are very important for our body.

We can conduct simple experiments, to know if our food contains any of these nutrients. Both cooked food and a raw ingredient may contain one or more of these nutrients.

The tests for presence of carbohydrates, proteins and fats are simpler to do as compared to the tests for other nutrients.

If the required solutions are not readily available in your laboratory, they can be prepared as given below,

Preparation of solutions, test for carbohydrates, test for fats, test for proteins, Components of food, NCERT science class 6


Test for carbohydrates

Take the food item in the test tube and add 2-3 drops of dilute iodine solution to it. After some time if you will notice that color changes to black-blue, it indicates the presence of starch in the food item. The change in color to black-blue is because of the reaction of starch with iodine.

Test for Proteins

Take the food item in the test tube. Add 10 drops of water to it and mix well. Now using a dropper add 2 drops of copper sulphate and ten drops of caustic soda (sodium hydroxide) solution. Mix well and keep it undisturbed for some time. After some if you observe the development of violet color in the test tube, it indicates the presence of the proteins.

Test for fats

Take the food item in a paper and wrap it. Try to crush it taking care that the paper is not torn. Take out the food item and allow the paper to be dried for some time. If you can find the oil spots on the paper it indicates the presence of Fat in the food item.



Foods containing fats and carbohydrates are called energy giving foods. Fats give much more energy compared to carbohydrates. Proteins are need for growth and repair of our body. They called Body building foods. Vitamins help in protecting our body from diseases and also keep our eyes, skin, bones and teeth healthy.

Vitamins are of different kinds known by different names namely vitamin A, vitamin C, vitamin D, vitamin E, and vitamin K. There is also a group of vitamins called vitamin B-complex which includes Vitamin B1, Vitamin B2, Vitamin B3, Vitamin B5, Vitamin B6, Vitamin B7, Vitamin B9 and Vitamin B12.

Our body needs all types of vitamins in small quantities. vitamin A keeps our skin and eyes healthy. vitamin C helps body to fight against many diseases. vitamin D helps our body to use calcium for bones and teeth. Foods




Minerals are needed by our body in small amounts. Each one is essential for proper growth of body and to maintain good health.

Most food items, usually, have more than one nutrient. But one particular nutrient maybe present in much larger quantity than in others. For example, rice has more carbohydrates than other nutrients. Thus, we say that rice is a “carbohydrate rich” source of food.

Apart from nutrients, our body also needs good amounts of dietary fibers and water. Dietary fibers are also known as roughage. Roughage is mainly provided by plant products in our foods.

Whole grains and pulses, potatoes, fresh fruits and vegetables are main sources of roughage. Roughage does not provide any nutrient to our body, but is an essential component of our food and adds to its bulk. This helps our body get rid of undigested food.

Water helps our body to absorb nutrients from food. It also helps in throwing out some wastes from body as urine and sweat. Generally, we get most of the water that our body needs from the liquids we drink such as water, milk and tea. In addition, water is also added in most of the dishes while cooking. Moreover most of the food materials themselves contain water.


Balanced diet

The food we normally eat in a day is our diet. For growth and maintenance of good health, our diet should have all the required nutrients in right proportions. It should also contain some amount of water and dietary fibers. Then this kind of diet is called as Balanced Diet. The amount of Balanced diet also depends upon the age and the amount of physical work done by a person.

Pulses, groundnut, soybean, sprouted seeds (moong and Bengal gram), fermented foods (South Indian foods such as idlis), a combination of flours (missi roti, thepla made from cereals and pulses), banana, spinach, sattu, jaggery, available vegetables and other such foods provide many nutrients. Therefore, one can eat a balanced diet without expensive food materials.

Eating the right kind of food is not enough. It should also be cooked properly so that its nutrients are not lost.

If the vegetables and fruits are washed after cutting or peeling them, it may result in the loss of some vitamins. Moreover the skins of many vegetables and fruits contain vitamins and minerals. Also, repeated washing of rice and pulses may remove some vitamins and minerals present in them.

We all know that cooking improves the taste of food and makes it easier to digest. At the same time, cooking also results in the loss of certain nutrients. Many useful proteins and considerable amounts of minerals are lost if excess water is used during cooking. Vitamin C gets easily destroyed by heat during cooking.

It can be very harmful for us to eat too much of fat rich foods and we may end up suffering from a condition called obesity.


Deficiency diseases

A person may be getting enough food to eat, but sometimes the food may not contain a particular nutrient. If this continues over a long period of time, the person may suffer from its deficiency.

Deficiency of one or more nutrients can cause diseases or disorders in our body. Diseases that occur due to lack of nutrients over a long period are called deficiency diseases.

If a person does not get enough proteins in his/her food for a long time, he/she is likely to have stunted growth, swelling of face, discoloration of hair, skin diseases and diarrhea.

If the diet is deficient in both carbohydrates and proteins for a long period of time, the growth may stop completely. Such a person becomes very lean and thin and so weak that he/she may not even be able to move.

Deficiency of different vitamins and minerals may also result in certain diseases or disorders. All deficiency diseases can be prevented by taking a balanced diet. Some of these are mentioned below.

Vitamin/Mineral Deficiency Symptoms
Vitamin A Loss of vision Poor vision, loss of vision in darkness (night), sometimes also leads to loss of complete vision
Vitamin B1 Beriberi Weak muscles and very little energy to do work
Vitamin C Scurvy Bleeding gums, wounds take longer time to heal
Vitamin D Rickets Bones become soft and bent
Calcium Bone & tooth decay Weak bones, tooth decay
Iodine Goiter Glands in the neck appear swollen, mental disability in children
Iron Anaemia Weakness

To ensure that our meals have a balance of all the nutrients required for normal functioning of the body, various regions have various varieties of foods and main course and side dishes.

Link to Solutions on this topic

- Share with your friends! -