AGAR
SYNONYM
Agar – agar, Vegetable gelatin, Japanese isinglass.
BIOLOGICAL SOURCE
Dried gelatin substance obtained from Gelidium amansi (Fam: Gelidaceae) and several other species of red algae like Gracilaria (Fam: Gracilariaceae)
GEOGRAPHICAL SOURCE
It is produced commercially in Japan, Australia, New Zealand, USA and India. In India, it is produced in the coastal region of Bay of Bengal.
PREPARATION
In Japan, the red algae are grown on the bamboos spread in the ocean.
The collection of the material is done in May and October.
Sea weeds are scrapped from the bamboos (dried and bleached)
To remove foreign materials like shells, sand, etc. The entire material is taken to the high altitudes where it is washed and bleached by sun.
Boiled for 5 to 6 hrs with large quantity of dil. Acidified water (about 1 part of algae with 6 parts of water).
This extract is then strained while hot through the cloth. Transferred to wooden troughs. On cooling, jelly is produced.
Rectangular solid pieces of jelly are then passed through the netting under pressure. Narrow strips, thus formed are allowed to melt during the day time in the sun which removes the excess of water
This operation is continued for several days. Final product.
DESCRIPTIONS:
COLOR : Depending upon the shape and the form, it is yellowish – grey or white to nearly colourless.
ODOR : odourless
TASTE : mucilaginous
SHAPE : found in various forms like strips, sheets, flakes or coarse powder.
CHEMICAL CONSTITUENTS:
Agarose and agaropection.
CHEMICAL TESTS:
1. Boil about 1.5 gm agar with 100ml of water. Cool the solution to room temperature. It forms a stiff jelly.
2. When mounted in the solution of Ruthenium red and examined under microscope, the mounted particles acquire pink color.
3. Sample + KOH Canary yellow color (agar)
4. An ash of agar is treated with dil. Hcl. This on microscopic examination shows fragments of diatoms.
5. Sample + N/50 Iodine Deep crimson to brown color
6. Aqueous soln. of drug + 0.5ml of dil. Hcl H2O bath divide into 2 parts.
30 mins
a. 1st part + 10% caustic soda solution+ 2ml of Fehling’s solution
in a H2O bath
Reddish brown color ppt
b. 2nd part + Bacl2 (10%) soln white ppt.
7. Sample + Soda lime No NH3 produced
8. Sample + Million’s reagent No ppt
9. Sample + Tannic acid (10%) soln No ppt
USES:
As a bulk laxative.
As a culture medium in bacteriology.
Used as an emulsifying agent.
2. SYNONYM
Agar – agar, Vegetable gelatin, Japanese isinglass.
BIOLOGICAL SOURCE
Dried gelatin substance obtained from Gelidium amansi
(Gelidaceae) and several other species of red algae like Gracilaria
(Gracilariaceae)
GEOGRAPHICAL SOURCE
It is produced commercially in Japan, Australia, New Zealand,
USA and India. In India, it is produced in the coastal region of Bay of
Bengal.
3.
4. PREPARATION
In Japan, the red algae are grown on the bamboos spread in
the ocean.
The collection of the material is done in May and October.
Sea weeds are scrapped from the bamboos
(dried and bleached)
To remove foreign materials like shells, sand, etc.
5. The entire material is taken to the high altitudes where it is
washed and bleached by sun.
Boiled for 5 to 6 hrs with large quantity of dil. Acidified water
(about 1 part of algae with 6 parts of water).
This extract is then strained while hot through the cloth.
Transferred to wooden troughs.
On cooling, jelly is produced.
6. Rectangular solid pieces of jelly are then passed through the netting
under pressure
Narrow strips, thus formed are allowed to melt during the day time
in the sun which removes the excess of water
This operation is continued for several days.
Final product.
7. DESCRIPTION
COLOR : Depending upon the shape and
the form, it is yellowish – grey or white to
nearly colourless.
ODOR : odourless
TASTE : mucilaginous
SHAPE : found in various forms like strips,
sheets, flakes or coarse powder.
10. CHEMICAL TEST
1. Boil about 1.5 gm agar with 100ml of water. Cool the solution to
room temperature. It forms a stiff jelly.
2. When mounted in the solution of Ruthenium red and examined
under microscope, the mounted particles acquire pink color.
3. Sample + KOH Canary yellow color (agar)
4. An ash of agar is treated with dil. Hcl. This on microscopic
examination shows fragments of diatoms.
5. Sample + N/50 Iodine Deep crimson to brown color
11. 6. Aqueous soln. of drug + 0.5ml of dil. Hcl H2O bath divide into 2 parts.
30 mins
a. 1st part + 10% caustic soda solution+ 2ml of Fehling’s solution
in a H2O bath
Reddish brown color ppt
b. 2nd part + Bacl2 (10%) soln white ppt.
7. Sample + Soda lime No NH3 produced
8. Sample + Million’s reagent No ppt
9. Sample + Tannic acid (10%) soln No ppt
12. USES
As a bulk laxative.
As a culture medium in bacteriology.
Used as an emulsifying agent.
E.COLI COLONIES IN AGAR MEDIUM
