New sources of water-soluble seed gums

Seeds from 300 species representing 139 genera in 31 plant families have been surveyed for water-soluble gum (mucilage). Four families, Leguminosae, Plantaginaceae, Cruciferae, and Convolvulaceae, have species the seeds of which contain more than 18% gum. The legumes were studied most intensively. Of 163 legume species in 45 genera, 36 contained more than 18% gum, and 54 contained 10 to 18%. Gums from 20 legumes have been analyzed for component sugars; these are all galactomannans. Their specific optical rotation increases regularly as the mannose content decreases. In the legume seed, gum often comprises most of the endosperm. These galactomannan gums can be separated by a milling process to provide commercial-grade gums useful for paper additives and for sizing, thickening, or stabilizing agents.