ABSTRACT
Arabinogalactan is a water-soluble gum that is found at remarkably high concentrations in the heartwood of all larch species. Larchwood gum goes by the general names of arabinogalactan, Stractan, wood gum, and wood sugar. A clear aqueous solution containing up to 75% arabinogalactan, with pH 4.0—4.5, can be prepared. Solubility increases with increasing temperature. An effort to make commercial use of larch gum was launched by International Chemical Products, Montana, toward the beginning of the 1920s. In the early 1960s, a countercurrent hot-water extraction system was developed, and the gum was manufactured commercially by the St Regis Paper Co. under the trade name Stractan. The gum is approved in the United States by the Food and Drug Administration as a food additive that can act as an emulsifier, stabilizer, and binding or bodying agent. The best commercial source of the gum is the heartwood of Larix occidentalis.
