Agar

• Agar is a gelatinous substance from red algae used as a culture medium in microbiology and food industry.
• Agar supports microbial growth, acts as a stabilizer, thickener, and is vital in pharmaceutical formulations.

General Information

• Synonyms: Agars-Agars, Gelose.

• Biological Source:

  • Extracted from red algae Gelidium amansii, Gracilaria species.
• Family: Gelidiaceae, Gracilariaceae.

• Geographical Source:

  • Found in Japan, India, Sri Lanka, USA, Indonesia.

Macroscopical Characters of Agar

• Color: White to pale yellow.
• Texture: Brittle, transparent sheets or powder.
• Taste: Bland.
• Odor: Odorless.

Chemical Constituents of Agar

• Polysaccharides: Agarose, Agaropectin.
• Sugars: Galactose.

Preparation of Agar

1. Harvesting: Red algae collected and dried.
2. Extraction: Boiled in water to extract polysaccharides.
3. Purification: Filtered, cooled, and dried into sheets or powder.

Evaluation

• Solubility: Insoluble in cold water, dissolves in hot water forming a gel.

• Purity Tests:

  • Gel Strength Test (Viscosity test).
  • Sulphated Ash Test (Checks inorganic impurities).

Preservation & Storage

• Stored in moisture-free conditions to prevent degradation.

Therapeutic Uses

• Laxative (adds fiber to diet).
• Used in microbiological culture media.
• Emulsifying agent in pharmaceuticals.

Commercial Utility

• Used in food industry (jellies, ice creams).
• Used in cosmetics (face masks, skin gels).

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