Exudate gums

Abstract

Exudate gums have been used for centuries in a variety of fields; they have retained their importance despite the many alternative gums, with similar typical performances, that have since come into existence. The gums exude from trees and shrubs in tear-like, striated nodules or amorphous lumps, then dry in the sun, forming hard, glassy exudates of different colors, from white to pale amber for gum arabic, pale gray to dark brown for karaya gum, and white to dark brown for tragacanth. Gum production increases at high temperatures and limited moisture, and yields can be increased by making incisions in the bark or stripping it from the tree or shrub. Exudate gums have been utilized for food applications for many years, for emulsification, thickening and stabilization. Gum arabic, tragacanth and karaya gum are safe for human consumption, based on a long, safe history as well as on recent toxicological studies. Tree gum exudates are also used in non-food applications, such as pharmaceuticals, cosmetics, textiles, lithography and minor forest products (Wang and Anderson, 1994).