how will you determine whether the given food item contains protien or not ?
Answers
Explanation:
Following steps are used to test if a food item contains protein.
1) Take a small quantity of the food items to be tested.
2) Grind/mash the food item.
3) Put the food item into a test tube.
4) Add 10 drops of water and shake the test tube.
5) Add two drops of copper sulphate solution to the test tube, using a dropper.
6) Add 10 drops of caustic soda solution using a dropper and shake the test tube.
7) Let the test tube rest in a test tube stand for a few minutes.
8) Observe the colour of the mixture.
9) Violet colour indicates the presence of proteins in the tested food item.
Answer:
The following are the simple tests carried to find the presence of proteins in the given food samples.
Biuret test
The compounds with peptide linkage undergo this test. Proteins are polypeptides of amino acids linked together by peptide bonds. An alkaline solution of protein is treated with a drop of aqueous copper sulfate and a bluish violet color is obtained.
Note: Formation of violet coloration confirms the presence of Proteins.
Nihydrin test
Proteins react with pyridine solution of ninhydrin and change to a colored solution from a deep blue to violet-pink or sometimes even to a red color. Ninhydrin solution is prepared by dissolving 0.1gm of ninhydrin in about 100ml of distilled water. But this solution of ninhydrin is unstable and can be kept for two days.
Note: The appearance of violet color solution confirms the presence of proteins.
Explanation: