Agar agar

Agar-agar or agar also known as china grass is a vegetarian gelatin substitute produced from seaweed. This white and semi-translucent vegetable gelatin contains a few calories and is an excellent source of a calcium, iron, and fiber. It is available in both flake, powder, and bar varieties, and can be used in several recipes as a stabilizing and thickening agent for custards, puddings, sauces, marshmallows etc.

General properties and Specifications of Agar agar or Agar or China grass or Gum agar:
Appearance: White solid, flake, powder, grass strips and bar.
Moisture: 12% to 20% as agreed between the buyer and the seller.
Melting Temperature: 85-95C
Insoluble matter: 1% maximum
Total Colony Count: 1000 cfu/gm maximum
Salmonella SP: Nil
E. Coli: Nil.

Specifications of Agar USP NF Grade:

Agar is the dried, hydrophilic, colloidal substance extracted from Gelidium cartilagineum (Linné) Gaillon (Fam. Gelidiaceae), Gracilaria confervoides (Linné) Greville (Fam. Sphaerococcaceae), and related red algae (Class Rhodophyceae).

Botanic characteristics:
Agar: Usually in bundles consisting of thin, membranous, agglutinated strips or in cut, flaked, or granulated forms. May be weak yellowish orange, yellowish gray to pale yellow or colorless. Is tough when damp, brittle when dry.
Histology: In water mounts Agar appears granular and somewhat filamentous; a few fragments of the spicules of sponges and a few frustules of diatoms may be present; in Japanese Agar, the frustules of Arachnoidiscus ehrenbergii Baillon often occur, being disk-shaped and from 100 microm to 300 microm in diameter.
Powdered Agar: White to yellowish white or pale yellow; in chloral hydrate its fragments are transparent, more or less granular, striated, and angular, and occasionally they contain frustules of diatoms.
Identification:
A: Iodine colors some of the fragments of Agar bluish black, with some areas reddish to violet.
B: When boiled with 65 times its weight of water for 10 minutes, with constant stirring, and adjusted to a concentration of 1.5%, by weight, with hot water, Agar forms a clear liquid which congeals at 32C to 39C to form a firm resilient gel, which does not melt below 85C.
Microbial limits: It meets the requirements of the test for absence of Salmonella species.
Water: If necessary, cut it into pieces from 2 mm to 5 mm square, and dry at 105C for 5 hours: it loses not more than 20.0% of its weight.
Total ash: not more than 6.5%, on a dry-weight basis.
Acid-insoluble ash: not more than 0.5%, on a dry-weight basis.
Foreign organic matter: not more than 1.0%.
Limit of foreign insoluble matter: To 7.5 g add sufficient water to make 500 g, boil for 15 minutes, and readjust to the original 500 g. To 100 g of the uniformly mixed material add hot water to make 200 mL, heat almost to boiling, filter while hot through a tared filtering crucible, rinse the container with several portions of hot water, and pass these rinsings through the crucible. Dry the crucible and its contents at 105 to constant weight: not more than 15 mg (1.0%) remains.
Arsenic: 3 ppm.
Lead: 0.001%.
Heavy metals: 0.004%.
Limit of foreign starch: A solution made by boiling 0.10 g of it in 100 mL of water does not, upon cooling, produce a blue color upon the addition of iodine.
Gelatin: Dissolve about 1 g in 100 mL of boiling water, and allow to cool to about 50. To 5 mL of the solution add 2 to 3 drops of a mixture of 0.2 M potassium dichromate solution and 3 N hydrochloric acid (4:1): no yellow precipitate is formed.
Water absorption: Place 5.0 g in a 100-mL graduated cylinder, fill to the mark with water, mix and allow to stand at 25C for 24 hours. Pour the contents of the cylinder through moistened glass wool, allowing the water to drain into a second 100-mL graduated cylinder: not more than 75 mL of water is obtained.

Specifications of Agar BP Ph Eur Grade:
Action and use: Excipient.

DEFINITION
Polysaccharides from various species of Rhodophyceae mainly belonging to the genus Gelidium. It is prepared by treating the algae with boiling water; the extract is filtered whilst hot, concentrated and dried.

CHARACTERS
Appearance: Powder or crumpled strips 2-5 mm wide or sometimes flakes, colourless or pale yellow, translucent, somewhat tough and difficult to break, becoming more brittle on drying.
Mucilaginous taste.

IDENTIFICATION
A. Examine under a microscope. When mounted in 0.005 M iodine, the strips or flakes are partly stained brownish-violet. Magnified 100 times, they show the following diagnostic characters: numerous minute, colourless, ovoid or rounded grains on an amorphous background; occasional brown, round or ovoid spores with a reticulated surface, measuring up to 60 microm, may be present. Reduce to a powder, if necessary. The powder is yellowish-white. Examine under a microscope using 0.005 M iodine. The powder presents angular fragments with numerous grains similar to those seen in the strips and flakes; some of the fragments are stained brownish-violet.
B. Dissolve 0.1 g with heating in 50 mL of water. Cool. To 1 mL of the mucilage carefully add 3 mL of water so as to form 2 separate layers. Add 0.1 mL of 0.05 M iodine. A dark brownish-violet colour appears at the interface. Mix. The liquid becomes pale yellow.
C. Heat 5 mL of the mucilage prepared for identification test B on a water-bath with 0.5 mL of hydrochloric acid for 30 min. Add 1 mL of barium chloride solution. A white turbidity develops within 30 min.
D. Heat 0.5 g with 50 mL of water on a water-bath until dissolved. Only a few fragments remain insoluble. During cooling, the solution gels between 35C and 30C. Heat the gel thus obtained on a water-bath; it does not liquefy below 80C.

TESTS
Swelling index: Minimum 10 and within 10 per cent of the value stated on the label, determined on the powdered herbal drug (355).
Insoluble matter: Maximum 1.0 per cent.
To 5.00 g of the powdered herbal drug (355) add 100 mL of water and 14 mL of dilute hydrochloric acid. Boil gently for 15 min with frequent stirring. Filter the hot liquid through a tared, sintered-glass filter (160), rinse the filter with hot water and dry at 100-105C. The residue weighs a maximum of 50 mg.
Gelatin: To 1.00 g add 100 mL of water and heat on a water-bath until dissolved. Allow to cool to 50C. To 5 mL of this solution add 5 mL of picric acid solution. No turbidity appears within 10 min.
Loss on drying: Maximum 20.0 per cent, determined on 1.000 g of the powdered herbal drug (355) by drying in an oven at 105C.
Total ash: Maximum 5.0 per cent.
Microbial contamination:
TAMC: acceptance criterion 1000 CFU/g.
TYMC: acceptance criterion 100 CFU/g.
Absence of Escherichia coli.
Absence of Salmonella.

LABELLING
The label states the swelling index.

Specifications of Agar FCC Food Grade:
INS: 406 CAS: [9002-18-0]

DESCRIPTION
Agar is commercially available as white to pale yellow bundles consisting of thin, membranous agglutinated strips, or in cut, flaked, granulated, or powdered forms. Agar is a generic name given to a group of related molecules with a repeating unit of agarobiose formed basically by D- and L-galactose units interlinked with _-1,3 and _-1,4 linkages. Approximately every tenth D-galactopyranose unit contains a sulfate ester group. It is extracted from the cellular walls of agarophyte seaweed, considering as such the red seaweed from phylum Rodophyta, which belong to the Gelidiceae, Gracilariaceae, and Ahnpheltiaceae families. It is insoluble in cold water, but it is soluble in boiling water.
Function: Stabilizer; emulsifier; thickener.

REQUIREMENTS
Identification:
A. Place a few fragments of unground sample or a small amount of the powder on a slide, add a few drops of water and examine microscopically. The sample appears granular and somewhat filamentous. A few fragments of the spicules of sponges and a few frustules of diatoms may be present.
B. While stirring continuously, boil 1 g of sample with 65 mL of water for 10 min, and adjust to a concentration of 1.5%, by weight, with hot water. A clear liquid results that congeals between 32C and 39C to form a firm, resilient gel that does not liquefy below 85C.
Arsenic: Not more than 3 mg/kg.
Ash: (Acid-Insoluble) Not more than 0.5%, calculated on the dried basis.
Ash: (Total) Not more than 6.5%, calculated on the dried basis.
Gelatin: Passes test.
Insoluble Matter: Not more than 1.0%.
Lead: Not more than 5 mg/kg.
Loss on Drying: Not more than 20.0%.
Starch: Passes test.
Water Absorption: Passes test.

For Original Monographs of IP Indian Pharmacopoeia BP British Pharmacopoeia USP US Pharmacopoeia FCC Food Grade product, please check with the respective web-pages or books.