This method describes how to determine the average degree of modification and homogeneity in barley malt and is expressed in %.
The procedure described here primarily serves as a means to assess commercial malt. Additionally, it can be employed in the malthouse as a means of monitoring modification and homogeneity, in which case green malt samples are taken once per day and dried to a moisture content of 10–15 %, e.g., with an infrared lamp, before performing the analysis.
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.