AGAR (malaysk.; synonym agar-agar) — the dense fibrous material received from some seaweed, forming dense gel (jelly) in aqueous solutions. The USSR gets from a laver of Ahnfeltia plicata (The White Sea, the Far East).
And. contains 70 — 75% of polysaccharides, 2 — 3% of proteins and other nitrogen-containing substances, 2 — 4% of ashes. In composition of polysaccharides A. D-and a L-galactose, a 3,6-angidro-L-galactose, pentoses, D-glucuronic and Pyroracemic acids and some other connections enter. Main components A. agarose and agaropektin, the representing high-molecular substances are. The structure of their macromolecules explains ability And. to formation of jelly by association in long appreciate these molecules, e.g. through sulphatic groups and multivalent cations:
And. it is dissolved in water during the heating and gelatinizes at the room temperature.
Ability And. to education steady studio use in food, textile and pharmaceutical industry, and also in laboratories, especially microbiological (see the Agar beef-extract, Mediums).
And. it is made in the form of colourless or yellowish cords, plates, whetstones, powder.
See also Gels .
Bibliography: Yirgensons B. Natural organic macromolecules, the lane with English, page 203, M:., 1965; Kochetkov N. K., etc. Chemistry of carbohydrates, page 536, M., 1967, bibliogr.
V. A. Popkov.