Test of carbohydrate in your food.

How to check carbohydrates in your food.

Molich'sTest of carbohydrate

Molisch's Test Procedure

• Add 2 ml of sample in clean test-tube and 2 ml H2O in another as control 

• Add tow to three drops of  α-naphthol (C₁₀H₈OH) dissolved in ethanol (C₂H₅OH) (Molisch's reagent) to the tubes

• Gradually, add concentrated vitriol along the inner walls of the test- tubes

• Evolution of a violet ring at the junction of the fluid layers confirms the presence of carbohydrate 

2. Benedict's Test

• Principle: The principle is that when an answer of reducing sugar is heated with Benedict's reagent, the alkaline washing soda converts the sugar into enediol*, and this enediol further the cupric ions of the reagent into enzymatic cuprous ions. The resulting precipitate of cuprous oxide is brick-red in a color that confirms the presence of reducing sugar. Lactose, maltose, and glucose provide a positive reaction to the present test.

• Requirements: Sample, distilled water, Benedict's reagent, test tubes, test-tube stand, test-tube holder, bunsen, and dropper.

What is Benedict's Reagent?

Alkaline Benedict's solution is employed to check the presence of reducing sugars. It has the following components:

a. Anhydrous Sodium Carbonate - imparts alkalinity to the reaction medium

b. Na₃C₆H₅O₇ reduced to cuprous ions during storage

c. Copper (II) Sulphate Pentahydrate - gives the cupric ions

d. Distilled water - used as a solvent

While you doing all these tests take some precautions given below.

1. Handle the glassware properly to avoid damage to self and glassware.

2. Don't allow any interaction of the body with chemicals.

3. Wear lab PPE kit advisable to the lab requirement.

4. Handle the glassware & machine properly.