Test Detection of Fats, Proteins and CarbohydratesQuestion 1

Carbohydrate It is a compound which contain hydrogen, carbon and oxygen. The biomolecule can be a polyhydroxy ketone, polyhydroxy aldehyde or any other compound which yields that after acid hydrolysis

Protein It is an organic compound which comprises of hydrogen, carbon oxygen and nitrogen. Sometimes it contains phosphorous and sulphur

Mona saccharide It is the simplest carbohydrate. It cannot be hydrolysed to any simpler form

Fatty acid This is a compound which comprise of hydrocarbon chains which are terminated with carboxylic acid groups.

Acid hydrolysis It is a chemical reaction which involves breaking down of an acid in the presence of water

Triglyceride It is also called a fatty acid. They are compounds which comprise of three carboxylic acids and triesters of glycerol

Question 2

Glucose + Copper hydroxide →gluconic acid+ water+ copper oxide

Question 3

Starch d-glucose

sucrose Glucose and fructose

Glyceryl tristearate Glycerol and acid

Protein (give the general products) Ammonium and carboxylic acid

Section B

Question 1

Molisch test

Sample Precipitate colour

Deionized water (the control) Colourless

1% glucose solution Purple ring at the junction of two liquids

1% sucrose solution Purple ring at the junction of two liquids

1%lactose solution Purple ring at the junction of the two liquids

1%starch solution Purple ring at the junction of the two liquids

Carbohydrate which gave a positive test lactose, starch, glucose and sucrose

Question 2

Benedict test

Sample Precipitate colour

Deionized water (the control) blue

1% glucose solution orange

1%sucrose solution blue

1% lactose solution orange

1% starch solution blue

Carbohydrate which gave a positive test quickly is glucose and lactose

Question 3

Iodine test

Sample Solution colour

Deionized water (the control) brown

1% glucose solution brown

1%sucrose solution brown

1%lactose solution brown

1%starch solution Blue-black

Which carbohydrate gave a positive test starch: 1% starch solution

B. Tests for Detecting Fats: Grease spot test.

Describe your observation: There was formation of a translucent patch indication of fats.

C. Test for Detecting Protein

1. Xanthoprotic Test

Sample Color before Adding NaOH Color After Adding NaOh

Deionized water Clear Clear

1% biuret solution Clear clear

2% biuret solution Clear clear

2% tyrosine solution Light yellow Dark yellow

% egg-albumen solution Light yellow Dark Yellow

2% glycine solution Clear Clear

Which Samples gave a positive test: tyrosine, egg-albumen, glycine

2. Biuret Test

Sample Solution Color

Deionized water colorless

1% biuret solution Blue color

2% biuret solution Blue color

2% tyrosine solution Blue color

% egg-albumen solution Violet color

2% glycine solution blue

Which Samples gave a positive test: albumen

Was there any difference between the two biuret samples? If so describe

3. Ninhydrin Test

Sample Solution Color

Deionized water yellow

2% tyrosine solution purple

% egg-albumen solution blue

2% glycine solution Deep purple

Which samples gave a positive test: tyrosine solution and glycine solution

D.

Food 1

Description of the Food- Food 2

Description of the Food –

Carbohydrate test: Benedict’s test gives an orange or red precipitate at the end of the test indicating presence of carbohydrate Carbohydrate test: Benedict’s test gives an orange or red precipitate at the end of the test indicating presence of carbohydrate

Fat test:  Grease spot test, B Fat test: Emulsion test: gives a less clear solution after the test indicating absence of fat

Protein test: Biuret test gives blue colour of the biuret reagent indicating negative for protein Protein test: Biuret test gives blue colour of the biuret reagent indicating negative for protein

Conclusion: It contains only carbohydrate Conclusion: Carbohydrate is present in higher levels.

E. Testing Milk

Source and description of milk sample: The milk is a rich nutrient whole meal produced by the mammary glands

Molisch Test Observation: A granule like purple layer Conclusion Carbohydrate is present

Benedict Test Observation: Blue Color turned to green, then to yellow-orange and the final color brown Conclusion: There was presence of reducing sugars

Iodine Test Observation: Yellowish color Conclusion: No presence of starch

2. Test for detecting Triglycerides: Grease Spot test

Observation: there was formation of translucent patch on the paper

Conclusion: Milk contains triglyceride

3. Tests for detecting Proteins

Xanthoprotic test Observation: After adding HNO3 a yellow precipitate appears. Adding NaOH makes the yellow solution darker. Conclusion

Protein present

Biuret Test Observation: Blueish violet color is observed Conclusion: Presence of proteins:

Ninhydrin Test Observation: The appearance of deep blue or purple color Conclusion: Presence of proteins

4. Summarize what you have learned about milk sample:

Milk contains casein this the major components of milk is protein as it showed a positive reaction in all the experiment. On the grease spot test, I learnt milk contained fat because of the translucent fat. The Benedict test proved milk contained reducing sugars while the Molisch test proved milk did also contain carbohydrate. However, using the iodine test, I learnt milk does not contain starch