Guar galactomannan (guar gum), locust bean galactomannan (locust bean gum) and tamarind galactoxyloglucan are used as thickeners and stabilizers in various industries due to their water-absorbing ability. However, the gel formation of these native polysaccharides is very weak or does not exist at all. In the present work, the polysaccharides were selectively oxidized by galactose oxidase (GO, EC 1.1.3.9), utilizing both the polysaccharide concentration and the degree of oxidation as variables. GO oxidizes primary alcohols to aldehydes with a high regioselectivity for the hydroxyl group at C-6 of galactose, and thus only the galactosyl side groups were modified. The rheological properties of the oxidized products significantly differed from the native polysaccharides. The viscosities of the products were higher, and they formed hydrogels. The hydrogels were found to be thermally stable throughout the temperature range from 20�C to 90�C, indicating they are highly potential materials for food and medical applications.

Polysaccharide hydrogels by enzymatic oxidation

243rd National Meeting (2012)

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