This method describes how to determine the moisture content of specialty malt.
Specialty malt intended for use in beer brewing or elsewhere in the food industry
This method describes how to determine malted barley varieties and how to detect mixtures of different barley varieties in one lot of malt.
Malt intended for use in beer brewing or elsewhere in the food industry
Malt intended for use in beer brewing or elsewhere in the food industry
A (modified) Congress wort is produced from malt samples prior to analysis. NDMA present in the Congress wort is extracted using dichloromethane followed by concentration of the eluate. The determination is performed with a gas chromatograph using a packed Carbowax 20M column with a specific TEA detector (thermal energy analyzer); nitrosodipropylamine (NDPA) serves as an internal standard.
This detector analyzes nitrosamine according to the following procedure:
After exiting the GC column, the separated substances are heated to 500 °C in a pyrolyzer. At this temperature, the N-NO bond of the nitrosamine is broken, thus forming an NO radical (NO۰):
The gas mixture then flows through a special filter (CTRTM gas stream filter), which only allows the carrier gas and the NO radicals to pass. After exiting the filter, the NO radicals flow into a reaction chamber along with ozone, which is created by a special generator. The following chemical reactions take place in the chamber:
|
NO• + O3 |
→ |
NO2• |
|
NO2• |
→ |
NO2 + h•ν |
These NO radicals react with ozone, forming nitrogen dioxide in an excited state (NO2•). The NO2• molecules decompose spontaneously to form nitrogen dioxide in its common form (NO2), emitting radiation (h•ν) with a wavelength of approx. 600 nm.
Malt intended for use in beer brewing or elsewhere in the food industry
The aliquot of an extract of malt is added to a buffered starch solution and allowed to stand for exactly 30 min at 20 °C. Then, the maltose – formed primarily from the starch through the action of the β-amylase – is measured using iodine and is determined according to the following chemical reaction:
Malt intended for use in beer brewing or elsewhere in the food industry
Using a buffer solution, malt extract is produced, and then under defined conditions the extract is incubated on an azo-barley glucan substrate. The substrate is coupled with an azo dye, which is degraded by the β-glucanase activity to form low-molecular weight fragments. After addition of the precipitating agent, these fragments stay in solution and can be spectrophotometrically determined in the supernatant after centrifugation. The absorbance in the supernatant depends directly upon the activity of the β-glucanase in the analyzed malt.
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