STRUCTURE OF CHIA SEED POLYSACCHARIDE EXUDATE

Chia seed gum varies in molecular weight from 0.8 to 2.0 x 10(6) daltons, as determined by gel filtration. beta-D-Xylose, alpha-D-glucose, and 4-O-methyl-alpha-D-glucuronic acid were obtained on hydrolysis in the respective ratios of 2:1:1. An aldobiouronic acid, 2-O-(4-O-methyl-alpha-D-glucopyranosiduronic acid)-D-xylose, was obtained by partial hydrolysis. A tentative structural unit proposed for the polysaccharide is a tetrasaccharide with 4-O-methyl-alpha-D-glucoronopyranosyl residues occurring as branches at O-2 of some beta-D-xylopyranosyl residues in the main chain consisting of (1-->4)-beta-D-xylopyranosyl-(1-->4)-alpha-D-glucopyranosyl(1-->4)-beta-D-xylopyranosyl units. A linear tetrasaccharide was characterized that incorporates these structural features.