EXPERIMENT NO. 04 ANALYSIS OF STARCH BY CHEMICAL TEST | PHARMACOGNOSY & PHYTOCHEMISTRY - I PRACTICAL

PHARMACOGNOSY & PHYTOCHEMISTRY - I PRACTICAL

ANALYSIS OF STARCH BY CHEMICAL TEST 

EXPERIMENT NO.4

Aim: Analysis of Starch by chemical tests.

Reference: 1. Mayur R. Bhurat, Md. Rageeb Md. Usman, Sanjay A. Nagdev, Practical Pharmacognosy & Phytochemistry – I, Published by S. Vikas And Company (Medical Publisher) Ppage. No. 17 – 18.

Requirements:

Apparatus: Test tubes, Beaker, Holder, Burner, Water bath, Tripod stand, Copper gauze etc.

Chemicals: α-naphthol, Conc.H2SO4, iodine etc.

Theory:  

Biological Source: Starch consists of polysaccharide granules obtained from the grains of Maize Zea mays L. or of rice oryza sativa L or of wheat Triticumae stivum L. (Family Graminae) or from the tubers of the potato Solanum tuberosum L.

Family: Solanaceae.

Description:

Color: White :( Rice and Maize starch), cream (Wheat), slight yellow (Potato).

Odor: Odorless.

Taste: Mucilaginous taste.

Shape: Fine powder or irregular, angular masses.

Solubility: It is sparingly soluble in cold water and mostly soluble in hot water after cooling it forms gel.

Chemical Constituents: Starch contains generally a mixture of two polysaccharides, amylopectin (α-amylose) and amylose (β-amylose).

(a) Amylopectin: it is the main constituent of most of the starches (more than 80%) and is present in outer parts of granules. It contains both strait chained and branched glucose unit. It is insoluble in water and is responsible for gelatinizing property. It gives bluish black colour with iodine solution.

(b) Amylose: it is most starches contain 20% amylose. It contains straight chained glucose units and is present in inner parts of granules. It is soluble in water and produces blue colour with iodine solution.

Uses: It is mainly used as a dusting powder, Pharmaceutical aid, an antidote for iodine poisoning, Source of Food-nutrition, Protective and demulcent, in paper-sizing, textile industry, in laundry Practice. It is the starting product form which liquid glucose, dextrose, dextrin are made. It is also used as a tablet disintegrating agent and diluents.

Chemical Test of Starch:

Sr.No	Chemical test	Observation	Inference
A)	Preliminary Test. 1. Colour	White  Cream Slight Yellow	Rice & Maize Starch  Wheat Starch  Potato Starch
	2. Odor	Odorless	Rice & Maize Starch, Wheat Starch, Potato Starch.
	3. Taste	Mucilaginous	Starch
	4. Soubility	Sparingly soluble in cold water and mostly soluble in hot water after cooling it forms gel.	Starch
B)	General Test: 01. Molisch’s test : In a test tube, add 2 ml of the test carbohydrate solution and2 drops of a-naphthol solution. Carefully incline the tube and pour drop wise conc. H-,SO,, using a dropper, along the sides of the tube.	Violet colour ring at the junction of the two liquids.	Carbohydrate, is present
C)	Confirmatory Test: 1. Iodine Test: Add 2 drops of iodine solution to about 2 mL of the carbohydrate containing test solution.	Blue colour observes.	Starch is present
	2. Boil 1 gm starch with 15 ml water and cool it.	Translucent _ jelly like mass observed.	Starch is present
	3. In above form of translucent jelly add few drop of iodine solution	Deep blue color formed and on warming this color disappears and after cooling again reappears.	Starch is confirmed

Result: The given Sample Crude drug was identified by performing chemical test and the sample was found to be Starch.