[Short Notes] NCERT Class VI – Science, Components of Food – Chapter 2 – Part 1
Read complete book (must) at NCERT Class VI – Science, Science, Components of Food – Chapter 2
Our body needs different kinds of food for some special purpose
Each dish is usually made up of one or more ingredients, which we get from plants or animals.
These ingredients contain some components called nutrients that are needed by our body. The major nutrients in our food are named carbohydrates, proteins, fats, vitamins and minerals. In addition, food contains dietary fibres and water which are also needed by our body.
We can easily test the presence of carbohydrates, proteins and fats.
Solutions of iodine, copper sulphate and caustic soda is required to carry out these tests.
Test for Carbohydrate
There are many types of carbohydrates. The main carbohydrates found in our food are in the form of starch and sugars.
Test for Starch
Take a small quantity of a food item or a raw ingredient. Put 2-3 drops of dilute iodine solution on it. Observe
if there is any change in the colour of the food item. Did it turn blue-black?
A blue-black colour indicates that it contains starch.
Test for Protein
Take a small quantity of a food item for testing. If the food you want to test is a solid, you first need to make a paste of it or powder it.
Put some of this in a clean test tube, add 10 drops of water to it and shake the test tube.
Add two drops of solution of copper sulphate and ten drops of solution of caustic soda to the test tube
A violet colour indicates presence of proteins in the food item.
Test for Fats
Take a small quantity of a food item. Wrap it in a piece of paper and crush it. Take care that the paper does not tear.
Now, straighten the paper and observe it carefully.
An oily patch on paper shows that the food item contains fat. The food items may sometimes contain a little
water. Therefore, after you have rubbed an item on paper, let the paper dry for a while.
If no oily patch shows up after this, the food item does not contain any fat.