white to pale yellow or tan crystalline powder, no odour
A dried hydrophilic, colloidal polygalactoside derived from the entire plant (minus the roots) of Gelidium cartilagineum (L.) Gaillon or Gracilaria confervoides (L.) Greville. It is commercially available in bundles consisting of thin, membranous agglutinated strips or in cut, flaked granulated or powdered form. Although agar was discovered in Japan in 1658, it was introduced to Europe and the United States from China in the nineteenth century, where it was initially used as a gelatin substitute in the making of desserts. It soon became widely used as a solid bacteriological culture medium after its use by Robert Koch in his famous experiments. Its major uses in the food industry of today are in bakery products, confectionary, dairy products and canned meat and fish. It is also used in microbiology, dentistry and medicine.
The Gelidium species amansii and cartilageneum are the major sources of agar, although many species of Rhodophyceae are used. The weeds (agarophytes) used in the commercial product of agar grow from the tide line out to depths of 120 ft, and are harvested by waders along the shore at low tide, raked from small boats or picked by divers. Japan is the largest producer of agar. Because agar is soluble in hot water but relatively insoluble in cold water, it is extracted by boiling the agarophyte in water, filtering, cooling to form a gel, cutting into pieces and frozen, then thawing to free the agar from salts and other impurities that are soluble in cold water. The wet agar is repeatedly washed with cold water and finally dried. American and Japanese agar are graded according to published specifications. The high-quality American agar is divided into bacteriological, medicinal and dental grades, and the Japanese agar, into three grades and two subgrades. It is odorless or with a slight characteristic odor and mucilaginous taste. The structure of agar is not completely known. Chem
Flash point data for Agar are not available. Agar is probably combustible.
Substitute for gelatin, isinglass, etc. in making emulsions including photographic, gels in cosmetics, and as thickening agent in foods especially. confectionaries and dairy products; in meat canning; in production of medicinal encapsulations and ointments; as dental impression mold base; as corrosion inhibitor; sizing for silks and paper; in the dyeing and printing of fabrics and textiles; in adhesives. In nutrient media for bacterial cultures.
FDA: 21 CFR 150 et. seq., 184.1115, 582.7115; 27 CFR 24.243
FDA (other): Approved for OTC use (21 CFR 310.545); HOC (1992)
JECFA: ADI: Not limited (1973)
Flammable and/or toxic gases are generated by the combination of alcohols with alkali metals, nitrides, and strong reducing agents. They react with oxoacids and carboxylic acids to form esters plus water. Oxidizing agents convert them to aldehydes or ketones. They exhibit both weak acid and weak base behavior.
Air & Water Reactions