P. ( rice extract) . Q ( ripe banana). R(wheat). S(potato extract) test tubes....... ( i) 4 test tube P Q R and S as shown below contain the following. On adding 2 drop of iodine to is test tube ,which will not show blue black colour ? (ii) In a food sample taken in a test tube 2-4 drop of conc. HCL was added by Suman for checking the presence of adulterant in food. The development of which specific colour suggest metanil yellow adultreation
Answers
Thank you for the question.
The answer is given in two parts.
i) The test tube Q, containing the ripe bananas will not show blue-black color.
Reasoning
- Addition of iodine is done to find the presence of starch in a food sample.
- The food samples in the test tubes P, R, and S namely rice extract, wheat extract, and potato extract contain starch.
- But in Bananas the starch is present only in unripe bananas and as the fruit ripens the starch is converted to sugar.
So it does not turn blue black color indicating the absence of starch.
ii ) The appearance of pink color suggests metanil yellow adulteration.
Reasoning
- Metanil yellow is a dye used for cloths and it is banned for using in foods.
- Addition of 2-4 drop of conc. HCL to food sample is a test for the presence of the adulterant Metanil yellow.
- When 2-4 drop of conc. HCL is added to the food sample taken in a test tube, the yellow color changes into pink, suggesting the presence of metanil yellow.
Hope it helps.