Practical Pharmacognosy Starch

Starch

Plants containing starch

 Cereal seeds contain 50- 65 % starch

Ginger rhizomes 50% starch

Potato tubers 80- 90% starch

Commercial sources of starch

1Corn starch: isolated from the caryopses of 

Zea mays L. – (Graminae)

2Rice starch: isolated from the caryopses of

Oryza sativa L. – (Graminae)

 3Potato starch: isolated from the tubers of Solanum tuberosum L. – (Solanaceae)

Properties of Starch

 1White mass powder, odorless with starchy taste

2Insoluble in water and form colloidal solution with water

3Starch + I₂ → Deep blue color

 4Starch + NaOH or chloral hydrate → gelatinization

 5Starch + H₂O → gel ( with heat)

 6Corn starch and wheat starch have neutral pH

Rice starch has slightly alkaline pH Potato starch has slightly acidic pH

Identification tests for starch

1Starch + H₂O → gel (jelly form) with heat

2Starch + I₂→ deep blue → colour disappears (with heating) → the colour reappears with cooling

The general uses

 1Nutritive

2Demulcent

 3Pharmaceutical uses as tablets filler and binder

 4Antipruritic: Baby paste®- (Vitamed company) used in case of diaper rash, skin irritation (ZnO, Starch)

5Industrial uses: papers, clothes

6. Antidote in case of poisoning from Iodine

 

Practical Pharmacognosy Trichomes (Hairs)