Studies on Tannins of Fruits and Vegetables

Part XIII. Adsorption of tannins with curdlan type polysaccharide 13140

Abstract

The absorbability of tannins was studied with a curdlan-type polysaccharide 13140 (PS), which was an insoluble β-1, 3-glucan produced by some mutant of Alcaligenes faecalis var. myxogenes and gelatinized by heating its water suspension. The absorption was completed within half an hour and was not affected by pH in the range of 3-8, but it was reduced with temperature increase and considerably with the presence of ethanol. The tannin removing ability of PS gel, which was made by heating together with tannin, was equal to that of ungelatinized PS. Since PS absorbed poorly low molecular polyphenolics but it absorbed considerably ordinary tannin present in fruits extracts, it is supposed that PS may be utilized as an astringency removing agent. The hardness of PS gel fell off remarkably with coexistence of tannin and therefore the care should be taken with the process of PS jelly.