Test for Carbohydrates, Proteins and Fats – MeitY OLabs

Test for Carbohydrates, Proteins and Fats – MeitY OLabs

November 1, 2019 0 By Ewald Bahringer


Test for Carbohydrates, Proteins and Fats CARBOHYDRATES Glucose Benedict’s Test Materials required: Dropper, Benedict’s reagent, banana extract
in a test tube, test tube holder, beaker containing water and Bunsen burner. Procedure: Using a dropper, take a small quantity of
Benedict’s reagent. Add the reagent to the test tube containing
banana extract. Using a test tube holder, hold the test tube
firmly and place it in a water bath. The colour changes from blue to green and
finally to orange or brick red indicating the presence of glucose. Fehling’s Test Materials required: Droppers, Fehling’s solution A, Fehling’s
solution B, banana extract in a test tube, test tube holder, beaker containing water
and Bunsen burner. Procedure: Using a dropper, take a small quantity of
Fehling’s solution A. Add the reagent to the test tube containing
banana extract. Using a fresh dropper, take a small quantity
of Fehling’s solution B. Add the reagent to the test tube containing
banana extract. Using a test tube holder hold the test tube
firmly and place it in a water bath. The colour changes from blue to green and
finally to orange or brick red indicating the presence of glucose. Sucrose Materials required: Dropper, HCl, NaOH, Benedict’s reagent, sugarcane
extract in a test tube, test tube holder, beaker containing water and Bunsen burner. Procedure: Using a dropper, take a small quantity of
concentrated HCl. Add 2 to 3 drops of concentrated HCl into
the test tube containing sugarcane extract. Boil the sample in a water bath for 2 minutes,
holding the test tube firmly with a test tube holder.
This hydrolyses sucrose into glucose and fructose. Using a dropper, take a small quantity of
NaOH solution. Add few drops of NaOH solution into the test
tube to make the solution alkaline. Now we can perform Benedict’s test to this
solution for the presence of glucose. Using a dropper, take a small quantity of
Benedict’s reagent. Add the reagent to the test tube containing
sample. Boil the sample in a water bath for 2 minutes,
holding the test tube firmly with a test tube holder.
The colour changes from blue to green and finally to orange or brick red indicating
the presence of glucose. Starch Iodine Test Materials required: Dropper, Iodine solution and potato extract
in a test tube. Procedure: Using a dropper, take a small quantity of
iodine solution. Add 5 drops of iodine solution to the test
tube containing potato extract. Blue black colour indicates the presence of
starch in potato extract. PROTEINS Biuret Test Materials Required: Droppers, 1% CuSO4, 40% NaOH solution and
egg albumin in a test tube. Procedure: Using a dropper, take 1 ml of 40% NaOH solution.
Add NaOH solution to the test tube containing egg albumin.
Using a fresh dropper, take a small quantity of 1% CuSO4 solution.
Add 2-3 drops of CuSO4 solution to the test tube containing egg albumin.
Shake the solution to mix it well. A violet colour appears in the test tube which
indicates the presence of proteins. Xanthoproteic Test Materials required: Droppers, concentrated HNO3, ammonia solution,
egg albumin in a test tube, test tube holder and a Bunsen burner. Procedure: Using a dropper, take 1 ml of concentrated
HNO3. Add HNO3 to the test tube containing egg albumin.
Boil the sample in a water bath for 2 minutes, holding the test tube firmly with a test tube
holder. Yellow precipitate appears in the test tube.
Wait for some time to cool the solution. Using a dropper, take 2 ml of ammonia solution.
Add ammonia solution to the sample. Yellow ppt. changes to orange in colour, which
indicates the presence of protein. Million’s Test Materials Required: Dropper, Million’s reagent and egg albumin
in a test tube. Procedure: Using a dropper, take 2 ml of Million’s regent.
Add Million’s reagent to the test tube containing egg albumin.
Wait for some time. Pink colour appears in the test tube, which
indicates the presence of protein. FATS Sudan III Test Materials Required: Dropper, Sudan III and oil in a test tube. Procedure: Using a dropper, take a small quantity of
Sudan III reagent. Add a few drops of Sudan III reagent to the
test tube containing oil. Shake the solution to mix it well.
Pink droplets appear, indicating the presence of fat in the sample.