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STUDIES ON FROZEN BEER PRECIPITATES II. CHEMICAL STRUCTURE OF THE β‐GLUCAN ISOLATED FROM THE PRECIPITATES
Author(s) -
Igarashi H.,
Amaha M.
Publication year - 1969
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1969.tb03214.x
Subject(s) - glucan , chemistry , hydrolysis , periodate , pentose , polysaccharide , chromatography , residue (chemistry) , fraction (chemistry) , organic chemistry , fermentation
A nitrogen‐free non‐starchy polysaccharide was isolated from frozen beer precipitate by repeated precipitation with ethanol, and further fractionated with ammonium sulphate into a pentose‐free fraction (G‐1) and a pentose‐containing fraction (G‐2). The G‐1 fraction, which constituted about 90% of the non‐starchy polysaccharide, was composed solely of glucose residues united by β‐linkages, as evidenced by the specific rotation (‐12°) and the infrared absorption spectrum. The G‐1 glucan gave glucose, celloblose, and laminaribiose on partial acid hydrolysis. Hydrolysis of the methylated G‐1 glucan gave 2,3,6‐tri‐O‐methyl‐D‐glucose and 2,4,6‐tri‐O‐methyl‐D‐glucose together with trace amounts of 2,3,4,6‐tetra‐O‐methyl‐D‐glucose and di‐O‐methyl‐D‐glucose (paper chromatography). Gas chromatography of the methanolysate of the methylated G‐1 glucan indicated the presence of methyl 2,3,6‐tri‐O‐methyl‐D‐glucopyranoside and methyl 2,4,6‐tri‐O‐methyl‐D‐glucopyranoside with a proportion of 3:1. The G‐1 glucan consumed 0·8 mole periodate per anhydroglucose residue on periodate oxidation. These results indicate that the G‐1 glucan is a β‐glucan of essentially linear structure containing β‐1,4‐ and β‐1,3‐linked glucopyranose residues in proportions of 3:1 to 4:1. The molecular weight of the G‐1 glucan was estimated as 114,000.