Components of Food: science class six
Why do we need food?
All living things, i.e. animals and plants require food. Without food no one can survive. All living things require energy to survive and perform all types of works, which they get from food.
Food gives other all materials which are required for the growth of body and fighting with diseases.
Food gives us energy without food we will not get necessary energy which is required by our body to perform various daily works.
What are Nutrients
Materials which give nutrition are called nutrients. There are mainly five types of nutrients. These are carbohydrates, fats, proteins, vitamins and minerals.
What are Components of Food
Nutrients found in food are called components of food. Different food items give different types of nutrients.
There are five main components of food; these are Carbohydrates, fats, proteins, vitamins, and minerals.
Carbohydrates
Carbohydrate is the main source of energy which a living organism requires to perform its daily work as well as to perform other physical activities.
Carbohydrates are sugars and starch like glucose and fructose. Glucose gives us quick energy. This is the cause that we get glucose after mixing in water to get quick energy.
Foods containing more carbohydrates are called energy giving food.
Sources of Carbohydrates
We eat grains in bulk like roti, rice, dal etc which contains mainly carbohydrates.
All grains are very good source of carbohydrates. For example rice, wheat, maize, barley, etc.
There are many vegetables and fruits which are also very good source of carbohydrates. For example potatoes, sweet potatoes, banana, etc.
Thus we get carbohydrates from rice, wheat, potatoes, bananas, sugar etc.
We get grains from the plants so it can be said that plants are the main source of carbohydrates.
Fats
Fats also give us energy. In fact, fats give much more energy compared to the same amount of carbohydrates.
But, body takes more time to break down the fats than the carbohydrates.
Fats work as cushion for the internal organs. This means fats protect our internal organs in the case of any jerk.
Food containing fats and carbohydrate are also called energy giving foods.
Excess carbohydrates which are not required by our body are stored under the skin in the body in the form of fats.
Fat is used by our body when excess energy is required or in the scarcity of energy. The fats stored in the body works as insulator and it keeps us warm.
Sources of Fats
We get fats from oily foods. We get fats from both plants and animals. Oils like mustered oil, groundnut oil, sunflower oil, coconut oil are plants fats. And butter and ghee are obtained from animals.
Meat, fish, egg, butter, milk, etc are the good source of fats.
Proteins
Proteins are needed for the growth and repair of our body.
As a building is made of large number of bricks, our whole of the body is made of cell. This means the unit structure of body is cell. Cells are made mainly of proteins.
To make new cells our body requires proteins. And to repair and replace old cells, our body needs proteins.
Children require more protein as they are in growing phase. Similarly a sick person requires more protein to get damaged cell repaired.
This is the cause that doctors give additional supplement of proteins in the form of drugs to the sick people.
This is the cause that foods containing proteins are called 'body building foods'.
Our hair, nails etc are made of a kind of proteins called 'Kerateins'.
Sources of Proteins
We get proteins from plants and animals.
Meat, fish, egg, milk, pulse, soyabeans, beans, etc are good source of proteins.
An adult person requires one gram protein per kilogram of his body weight.
Vitamins
Our body needs vitamins to proper and healthy functioning of our body. Vitamins help in protecting our body against diseases. Vitamins also help in keeping our eyes, bones, teeth and gums healthy.
Although our body requires a small quantity of vitamins but it is one of the most necessary chemical substance for a good health and functioning of body. In the condition of lack of proteins our body felt sick which is called deficiency disease.
So far 20 vitamins are isolated. Vitamins are named as A,C,D,E, and K and a group of vitamin B which is called vitamin B-Complex. B1, B2, B3, B6 and B12 are the names of vitamins B-complex.
Every vitamin is responsible for vital functioning of body. The word vitamins come from a Latin word "Vita" means life.
Our body requires different types of vitamins for different work.
Example: 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.
Sources of Vitamins
We get vitamins from plant source only, as our body can't make vitamins.
Milk, fish oil, papaya, spinch, carrot, etc. give us vitamin A.
Orange, tomato, lemon, guava, and all other citrus foods are rich sources of vitamin C.
Milk, eggs, fish, etc. are good sources of vitamin D. Our body also prepares vitamin D in the presence of sunlight.
Minerals
Minerals are essential for proper growth of body and to maintain good health.
Some of the minerals require by our body are sodium, potassium, Calcium, Chloride, Iron, Fluorine, Sulphur, Phosphorous and Iodine.
Although our body require minerals in a very small quantity but lack of any of the minerals in our body also leads to deficiency disease.
Example
Phosphorous and calcium are essential for building of strong bones and teeth. Calcium regulates the function of heart and clotting of blood.
Milk, green vegetables, peas and beans are rich sources of calcium.
Salt sold by many companies contain iodine. Iodine is a mineral and necessary for our body. Deficiency of Iodine leads to a disease called 'Goitre'.
Common Salt which we use in our house hold is Sodium Chlorine.
Iron is essential in the formation of a substance that helps red blood which carry oxygen to other parts of the body. Iron deficiency cause to a disease called 'Anemia'.
Egg, meat, green vegetables, turnip, germinated wheat grain are good source of iron.
Fluorine makes the enamel of our teeth hard and prevents the dental caries.
Potassium is necessary for the growth and keeping the blood and cells healthy. Deficiency of this mineral leads to weak muscles.
Green and yellow vegetables are good source of potassium.
Apart from nutrients our body requires Dietary fibres and water for proper functioning.
Roughage or Dietary Fibres
Besides nutrients our body needs dietary fibres and water. Dietary fibres are known as Roughage also.
Roughage is mainly provided by plant products in our foods. Whole grains and pulses, potatoes, fresh fruits and vegetables area main sources of roughage.
Roughage does not provide any nutrients to our body, but it is essential component of our food and adds to its bulk.
Fibres absorbs water and form in bulk to the faeces and keep it soft which ensure the smooth movement of waste through rectum.
It prevents constipation and ensure proper movement of bowl. Thats why we should take more fibrous food.
Cellulose presents in whole grain flour, whole pulses, green peas, leafy vegtables and fruits.
Water
Water helps our body to absorb nutrients from food. Water also helps in throwing out some wastes from body as urine and sweat.
Our body need water because all reactions like digestion in the body take place in the liquid state in the body. Without water digested food cannot be carried in the body. Waste materials such as urine and sweat are also thrown out from our body in the form of liquid. Even in the course of breathing our body loose water. Our blood is also in the liquid form.
We take water by drinking it. Food we take also contains water. Many fruits and vegetables also contain water.
Requirement of water by our body depends upon sweating and loss of water by body. During summer our body needs more water.
Dehydration
The condition of loss of excess water by our body is called dehydration.
In the case of dehydration we should take ORS which stands for Oral Rehydration Solution. In the condition of diarrhoea, vomiting, burn or sun stroke our body looses water and some important minerals like sodium and potassium which leads to cramps in muscles. In that condition one should treated quickly. Patient may die in the case of acute dehydration if not treated properly in time.
Tests for presence of nutrients in food
Test of the presence of starch in food
There are many types of carbohydrates. The main carbohydrates found in our food are in the form of starch and sugars. We can easily test if a food item contains starch, i.e. carbohydrate.
Things needed
(a) Iodine solution (Iodine solution can be prepared by by mixing tincture of iodine in test tube, half filled with water)
(b) Mashed boiled potato or paste of raw potato.
(c) Watch glass
(d) Dropper
Process
Some boiled mashed potato or paste of raw potato is taken in a watch glass or a glass plate.
Two or three drops of iodine solution is poured over it.
Observation
The color of potato changes to dark blue.
Inference
Change of color of potato to dark blue shows the presence of starch in it.
Thus, potato contains starch, i.e. carbohydrates.
This test can be repeated using boiled rice or bread or other food items.
If color of taken food items changes to dark blue, then the food items contain starch otherwise food item does not contain starch.
Test of the presence of fat in food
Things needed
(a) A Piece of White paper
(b) Potato chips (fried) or a small amount of butter or ghee or some drop of oil or food item to be tested for fat.
Process
(a) Fried Potato chips is wrapped in white paper.
(b) It is crushed carefully in such a way that the paper should not tear off.
(c) Now paper is unwrapped.
(d) And paper is observed carefully.
Observation
A clear translucent patch on paper is visible.
Inference
The translucent patch on paper shows that fat is present in chips.
This activity can be repeated with piece of butter, some drop of oil or other food items.
Test of the presence of protein in food
Things needed:
(a) Copper sulphate solution (copper sulpahate solution can be made by dissolving 2 gm copper sulphate in 100 ml water).
(b) Solution of caustic soda (Solution of caustic soda can be made by dissolving 10 gm caustic soda in 100 ml water)
(c) Paste of pulse (dal)
(d) Dropper
(e) Test tube
Process
(a) Take some paste of pulse in a test tube.
(b) Add some water to the paste.
(c) Add 2 to 3 drops of copper sulphate solution
(d) Add 10 drops of caustic soda solution in the test tube.
(e) Shake the test tube.
Observation
Color of solution in test tube becomes violet.
Inference
Protein is present in pulse.
Change of color of solution of food items made into violet proves the presence of protein in that.
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