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

Abstract

An improved method for the determination of β-glucan in beer and wort employing the fluorochrome Calcofluor is described. Dimethylsulfoxid (20% (v/v)) was used to obtain a reproducible binding ratio of Calcofluor to β-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 β-glucan for a wide range of beer and wort samples. Treatment of beers and worts with pure β-glucanase gave a low background fluorescence, thus indicating a high specificity of the method. From dialysis experiments it was found that low molecular β-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.