The β-glucan content of barley intended for use in beer production should be known.
The fluorochrome Calcofluor forms a complex with high molecular weight β-glucans (molecular weight greater than 5 kDa). Complex formation results in an increase in fluorescence; however, this fluorescence is extremely unstable due to photochemical degradation.
Through measurement in an automatic analysis system based on flow injection (flow-injection analysis, fig. 1), reproducible measurements for fluorescence and determination of β-glucan are possible. For barley analysis, it is necessary to use a short acid hydrolysis procedure to bring insoluble β-glucan into solution. The apparatus is calibrated using purified barley β-glucan standards.
Malt intended for use in beer brewing or elsewhere in the food industry.
This method is based upon on the fact that the β-glucan-rich cell walls of the endosperm are progressively broken down during malting. This process can be made visible by staining the cell walls that are still intact with the fluorochrome Calcofluor, which exclusively binds β-glucans starting at a molecular weight of approx. 10,000 D.
Modification is revealed by allowing the barley kernels, which have been cut in half, to react with Calcofluor (with Fast Green as a contrast medium). The kernels are subsequently examined under UV light (365 nm) in a suitable analyzer device. An intense, bright blue fluorescence occurs where unmodified endosperm cells are present, while the modified parts appear dark blue.
This method describes the fluorimetric determination of high-molecular weight β-glucans in malt.
Malt intended for use in beer brewing or elsewhere in the food industry
Fluorometric determination of high-molecular weight β-glucan
wort, beer
The fluorochrome Calcofluor forms a complex with high molecular weight β-glucans (molecular weight greater than 10,000 Da). Complex formation results in an increase in fluorescence; however, this fluorescence is extremely unstable due to photochemical degradation. Through measurement in an automatic analysis system based on flow injection (flow-injection analysis), reproducible measurements for fluorescence and determination of β-glucan are possible. The device is calibrated using standard solutions of purified β-glucan from barley.