| Abstract: | Tamarind kernel polysaccharide (TKP), isolated by fractionation of tamarind kernel powder, was heated at 153°C for 5 h in presence of 0.074% hydrochloric acid. The resulting product was fractionated to yield a homogeneous dextrin which on hydrolysis produced D -xylose, D -galactose and D -glucose in the molar ratio of 2:1:10. Methylation of the dextrin followed by hydrolysis yielded 2,3,4-tri-O-methyl-D -xylose (2 moles); 2,3,4,6-tetra-O-methyl-D -glucose (1 mole); 2,3,4,6-tetra-O-methyl-D -galactose (1 mole); 2,3,4-tri-O-methyl-D -glucose (1 mole); 2,3,6-tri-O-methyl-D -glucose (4 moles); 2,3-di-O-methyl-D -glucose (4 moles); and 2-O-methyl-D -glucose (trace amounts). Upon oxidation of the dextrin with sodium metaperiodate, 1.4 moles of the oxidant was consumed with concomitant liberation of 0.38 mole of formic acid. Reduction of the oxopolysaccharide with sodium borohydride followed by acid hydrolysis of the polyol produced erythritol, glycerol and ethylene glycol in the molar ratio of 8:3:2. The above results suggest that the main reaction during dextrinization of TKP is that of hydrolysis. The side branches of the polymer are hydrolyzed to a greater extent than its backbone. Transglycosidation, which is the predominant reaction in starch dextrinization, takes place only to a small extent. |
