Determination of the percentage of nitrogen that has dissolved in the wort during the Congress mash method
Suitable for (Congress) mash
The Kolbach index is used to express the quantity of the nitrogenous substances found in malt, which go into solution under the conditions present during the Congress mash method. It is a measure of the degree of proteolytic modification of the malt and also provides an indication for the quantity of proteolytic enzymes contained in the malt. The Kolbach index is less conclusive than other methods due to its dependence on the total nitrogen content and the provenance of the barley. Therefore, it must always be considered together with the total nitrogen content.
Applicable for all (laboratory) worts
The Congress wort is heated in order to inactivate the amylolytic enzymes, and afterwards, yeast is added and the wort is allowed to completely ferment out at a minimum temperature of 20 °C in a fermentation tube (fig. 1). The difference in the extract before and after fermentation is measured in order to calculate the limit of attenuation.
This method describes how to carry out the profile test.
beer, beer-based beverages, non-alcoholic beverages, mineral water
This method is employed for determining the appropriate level of intensity for certain product attributes.
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.
Barley malt intended for use in beer brewing or elsewhere in the food industry
High-molecular weight dextrins and starch present in the wort extracted from brewery spent grains are precipitated through the addition of ethanol, centrifuged and dissolved in phosphate buffer, followed by the addition of an iodine solution. Depending upon the molecular weight and degree of branching, a red to blue color forms, the intensity of which is measured spectrophotometrically at 578 nm.
Green beer, beer
The original gravity (p), apparent extract (EA) and real extract (ER) of the green beer and the fully matured beer are measured. From this, the apparent and real attenuation are calculated. Normally, only the apparent attenuation of beer is determined in practice.