THE VISCOSITY OF WORTS IN RELATION TO THEIR CONTENT OF β-GLUCAN

A procedure is given for assessing that proportion of wort viscosity which is attributable to β-glucan. Worts obtained from unkilned samples of malt which have been processed for 54 or 72 h show enhanced viscosity. This is principally due to β-glucan although the contribution of other constituents, absent from the wort of fully modified malt, is of significance. Barley variety is shown to have a pronounced effect on wort viscosity. Insoluble β-glucan is brought into solution in mashes at 65° C. The β-glucan isolated from malt which has been inactivated using aqueous ethanol prior to extraction at 65° C, is of higher specific viscosity than that isolated from control worts prepared at the same temperature. The introduction of a rest by mashing initially at 40° C results in the production of wort of lower viscosity, a decrease in the β-glucan content of the wort and a reduction in the specific viscosity of the β-glucan. There is no apparent relationship between the endo-β-glucanase content of the malts and either the viscosity of derived worts or the degree of breakdown of β-glucan which occurred during malting and mashing. Abrasion of barley, which is a factor assisting the distribution of enzymes during malting, acts to reduce wort viscosity.