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THE ACTION OF ENDO‐β‐1,3‐GLUCANASES ON BARLEY AND MALT β‐GLUCANS
Author(s) -
Bathgate G. N.,
Palmer G. H.,
Wilson G.
Publication year - 1974
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.2050-0416.1974.tb03617.x
Subject(s) - glucan , hydrolysis , chemistry , glucanase , xyloglucan , hordeum vulgare , glycoside hydrolase , molecular mass , gel permeation chromatography , enzyme , polysaccharide , agarose , food science , chromatography , biochemistry , polymer , biology , botany , poaceae , organic chemistry
The β‐glucan extracted from ungerminated barley with water at 40 °C has a much lower specific viscosity than the corresponding material isolated from a wort prepared at 65 °C from a two‐day germinated barley malt. Both glucans are similar in that they are polymers of β‐D‐glucose, with approximately 74% of the linkages in the β‐1,4 configuration and 26% in the β‐1,3 configuration. However, the two glucans are not hydrolysed to the same extent either by a partially purified bacterial endo‐β‐1,3‐glucanase or by a homogeneous endo‐β‐1,3‐glucanase from malted barley. The malt glucan is readily hydrolysed, causing a rapid decrease in specific viscosity but with no measurable increase in reducing power, whereas barley glucan undergoes only limited hydrolysis under similar conditions. Thus, different β‐glucan preparations from barley or malt may be identical in the proportion of β‐1,3 to β‐1,4‐linkages but the overall arrangement of linkages, and hence susceptibility to enzyme attack, differs according to the source and the method of extraction of the glucan. The molecular weights of both β‐glucan preparations and the products of their enzyme hydrolysis have been determined by agarose gel permeation chromatography. A simple model which illustrates the underlying structural relationships of the β‐glucans from barley and malt is suggested.