Introduction
Through this experiment, we will learn to check the presence of starch and adulteration in food. Let’s start with Food Sample Test for Starch and Adulteration.
Aim
To test the presence of
1. Starch in a given food sample,
2. Adulterant metanil yellow in dal.
1. To Test The Presence Of Starch In A Given Food Sample
Materials Required
1. Boiled rice or boiled potato,
2. Test tube,
3. Test tube holder,
4. Iodine solution,
5. Distilled water.
Theory
1. Starch is a complex carbohydrate consisting of molecules of glucose.
2. On reaction with the iodine, it gives a blue-black solution.
Procedure And Observation
| EXPERIMENT | OBSERVATION | INFERENCE |
|---|---|---|
| Take boiled potato or boiled potato in a beaker and mash it. After mashing, take a small amount of it in a test tube and add a few drops of iodine solution into it. | You will find a black-blue colour in the test tube. | It proves the presence of starch in the food sample. |
Result
Therefore, the given food sample, which is rice or potato, contains starch.
2. Test The Presence Of Adulterant Metanil Yellow In Dal
Materials Required
1. Dal,
2. Concentrated sulphuric acid,
3. Distilled water,
4. Test tube,
5. Test tube stand,
6. Test tube holder.
Theory
1. Adulterant metanil yellow gives the synthetic yellow colour to dal and turmeric.
2. As it is a dye, it is prohibited to use metanil yellow as a food colour.
3. Adulterant metanil yellow is very harmful to health as it can damage your liver and can affect your brain and intestine.
4. In order to check the presence of metanil yellow in dal, add a few drops of HCl to the food sample.
5. If the colour of the test tube changes to pink, it means metanil yellow is present in the food.
Procedure And Observation
| EXPERIMENT | OBSERVATION | INFERENCE |
|---|---|---|
| In a test tube, take 5g of dal and add 8-10 ml of distilled water into it. Shake it well. Separate this filtrate into another test tube. Add 2-3 drops of hydrochloric acid to the 1 ml of filtrate. | A pink or magenta solution will form. | It confirms the presence of metanil yellow in dal. |
Result
Adulterant metanil yellow is present in the dal.
Precautions
1. Use a test tube holder for holding the test tube while adding hydrochloric acid to the food sample.
2. Use required chemicals rightly.
Conclusion
In this way, we have proved the presence of starch and metanil yellow in the food sample.
VIVA Questions With Answers
Q.1 What was the aim of our experiment?
ANS. Food Sample Test for Starch and Adulteration. To test the presence of
1. Starch in a given food sample,
2. Adulterant metanil yellow in dal.
Q.2 What do you understand by starch?
ANS. Starch is a complex carbohydrate consisting of molecules of glucose.
Q.3 What is the form of stored carbohydrates in plants?
ANS. Starch.
Q.4 What is the form of stored carbohydrates in animals?
ANS. Glycogen
Q.5 Give one method through which you can distinguish between starch and glucose.
ANS. By dissolving both of them in water, we will find that starch is insoluble while glucose is soluble.
Q.6 What do you understand by adulteration?
ANS. When something harmful is added to food material, is called adulteration.
Q.7 What do you mean by metanil yellow?
ANS. It is a synthetic dye used to colour turmeric and dal.
Q.8 Name an adulterant of Arhar dal.
ANS. Metanil yellow.
Q.9 How would you check whether metanil yellow is present in dal or not?
ANS. In order to check the presence of metanil yellow in dal, add a few drops of HCl to the food sample. If the colour of the test tube changes to pink, it means metanil yellow is present in the food.
Q.10 How would you check whether starch is present in food or not?
ANS. In order to check the presence of starch in food material, add iodine to it. If it gives a blue-black solution, it means starch is present in the solution.
Saquib Siddiqui is a Mechanical Engineer and a content creator. He has special interest in science experiments and teaches the same to school and college students. He is also a technical lead at RUDE LABS PVT. LTD.
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