Answer: Please see explanation column
Explanation:
Sample provided to Brad = a piece of bread and egg yolk
1. We know that Bread is a carbohydrate containing starch
To investigate the presence of starch/ Carbohydrate in Bread
Materials: Bunsen burner,test tubes, food product -Bread,iodine solution
Method
1. Place a sample of bread into the test tube.
2. Place a few drops of iodine solution on the bread
3. Take observations.
4. Wait a few more minutes and note any other changes.
Observations
On addition of iodine to the bread , if we notice a blue-black coloration, we will conclude that the right component found in bread is starch /carbohydrate
The above procedure can also be confirmed using
-Molisch’s reagent–which gives us a purple or violet color ring on addition to the bread
- Fehling’s reagent –which gives a Red precipitate to indicate the presence of in the bread
-Benedict’s reagent –which gives Red precipitate to indicate the presence of carbohydrates in the bread.
-Tollen’s reagent – which gives us Silver mirror to confirm the presence of carbohydrate in the bread.
2. We know that egg yolk contains protein,
To investigate the presence of Protein in egg yolk using biuret test
Materials: Bunsen burner,test tube, food product -egg yolk , Aqueous copper sulfate solution
Method
1. Place a sample of egg yolk into the test tube.
2. Place a few drops of Aqueous copper sulfate solution on the sample of egg yolk
3. Note observations.
4. Wait a while and note any other changes.
Observations
On addition of Aqueous copper sulfate to the egg yolk , if we notice a violet coloration,we will conclude that the right component found in egg yolk is protein
The above procedure can also be confirmed using
Xanthoproteic test – which on addition of Nitric acid to the egg yolk gives a Yellow coloration
Millions test – which on addition of Mercuric sulfate in the presence of sodium nitrite and sulfuric acid to the sample of egg yolk gives Brick red color solution confirms the presence of proteins.
Ninhydrin test – which on addition of Pyridine solution of ninhydrin to the sample of egg yolk gives Violet color solution confirms the presence of proteins.
