Applying your understanding of the observable results possible for different Biochemical tests, identify the nutrient composition in samples 1,2,3. You should explain why you have arrived at each conclusion.
For each sample you must identify what the biomolecule contained in it is likely to be and then justify each decision based on the reagent tests carried out.
(food tests) Identify the substances that are present or
absent in the samples. Explain how these work.
These are the reagent solutions used in samples:
Sample 1:
Iodine solution: Blue-black
Biuret solution: No change
Benedict's solution: No change
Sample 2:
Iodine solution: No change
Biuret solution: Purple
Benedict's solution: No change
Sample 3:
Iodine solution: No change
Biuret solution: No change
Benedict's solution: Brick red
A positive iodine test means a starch is present.
A positive biuret test means a peptide is present. Histidine is the ony amino acid that will give a positive test.
A positive Benedict's test means a reducing sugar is present. Glucose will give a positiv test. Sucrose will also because the reagent reacts with fructose to give a reducing sugar.