An improved method for determining β-glucan in wort and beer by use of Calcofluor

Abstract

An improved method for the determination of~glucan in beer and wort employing the fluorochmme Calcofluor is described. Dimethylsulfoxid (20~ (v/v)) was used to obtain a reproducible binding ratio of Calcofluor to I}-glucan. The formed complex was precipitated by 77% ethanol and separated by centrifugation. The precipitate was dissolved in a glycine/NaOH buffer at pH ~ 10.0 and fluorescence was measured in a spectrofluorometer. The method correlates well with the established ammoniumsulphate precipitation method for ~-glucan for a wide range of beer and wort samples. Treatment of beers and worts with pure ~-glucanase gave a low background fluorescence, thus indicating a high specificity of the method. From dialysis experiments it was found that low molecular [3-glucans < 10,000 daltons only gave a slight binding to Calcofluor. The analysis is suitable for routine control in a brewery, allowing an output of at least 50 samples per day per person.

Arabinoxylan, β‐glucan and pectin in barley and malt endosperm cell walls: a microstructure study using CLSM and cryo‐SEM

“…Over the whole of the seed, a clear‐cut transition from non‐degraded to degraded endosperm was visible, which was formerly described as an enzymatic front that migrated centripetally from scutellum and aleurone inwards (Selvig et al ., 1986). This front resulted in the loss of β‐glucan staining, which meant that at least the degree of polymerization was decreased to levels below 55 (Jørgensen, 1983). The outer arabinoxylan cell walls remained intact, although the microstructure was less clear.…”

“…A 0.1 g L −1 solution of calcofluor was applied for 3 min. It was previously calculated that calcofluor binds to β‐glucan with a degree of polymerization of 55 and higher (Jørgensen, 1983).…”

“…This is linked to the binding characteristics of the dyes or dye carriers. Calcofluor White requires a chain length of at least 55 units to bind (Jørgensen, 1983), whereas the immunolabelling of pectin and xylanase labelling are both more sensitive. The signal intensities of different components are not correlated with their relative abundances, as different dyes and set‐ups are used.…”

The molecular weight distribution of β-glucan in wort from malts of different barley varieties at different stages of malting

“…The I]-glucans in wort and beer can be measured by the AMS-method or as previously described by the use of Calcofluor (CEP-method, 15,16). The relationship between the values determined by these methods and the viscosity of wort and beer has been investigated (14,16,19), and it was shown that the 15-glucan content could not fully explain the variation in viscosity.…”

“…The relationship between the values determined by these methods and the viscosity of wort and beer has been investigated (14,16,19), and it was shown that the 15-glucan content could not fully explain the variation in viscosity.…”