Gelation occurred by removing ~35% of the galactose residues from xyloglucan of tamarind seed using fungal β-galactosidase. This gel had the unique property of forming a gel on heating and reverting to a sol state on cooling. The gel strength at a higher temperature was greater than that at a lower temperature. The phase transition between sol and gel was reversible. The gel strength became greater with increasing removal ratio of galactose from xyloglucan. There were two sol-gel transition points; one was at a low temperature (sol to gel) and the other was at a high temperature (gel to sol). Gelation was believed to be induced by the association of main chains by hydrophobic binding. This report describes the biotechnological tailoring of polysaccharide properties using an enzyme, as a first step in modelling or designing a polysaccharide molecule.