Barley intended for the production of malt is evaluated with regard to pre-germination.
Visible pre-germination is evident at the rootlet and is therefore grounds for rejecting a barley lot. However, after the barley is cleaned and the rootlets are removed, the so-called “hidden pre-germination” can be made visible using the staining methods described below.
Kernels suspected of having pre-germinated are boiled for ½−1 min in a 20 % solution of copper sulfate, allowed to remain for 30 min in the hot solution and are subsequently rinsed with water. The acrospire is stained green, making it clearly visible.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
A specified quantity of water is evaporated, and any remaining moisture is subsequently eliminated in a drying oven. The dry residue is then weighed.
Determination of hydrogen peroxide (H2O2) in disinfectants.
Suitable for all solutions that contain hydrogen peroxide (H2O2) but no other peroxides.
Hydrogen peroxide oxidizes iodide to iodine, which is reduced by sodium thiosulfate (Na2S2O3) and recalculated as hydrogen peroxide.
|
H2O2 + 2 NaI +H2SO4 |
→ |
I2 + Na2SO4 + 2 H2O |
|
I2 + Na2S2O3 |
→ |
2 NaI + Na2S2O3 |
If the sample contains other peroxide-containing disinfectants in addition to hydrogen peroxide (H2O2), the method T-757-01-032 Peracetic-acid-based-disinfectants must be used.
The method provides an estimate of the portion of pre-germinated barley grains at the time of harvest or prior to storage in silos.
Barley intended for the production of malt is evaluated with regard to pre-germination.
The onset of germination is accompanied by the synthesis of enzymes, which can be made visible using fluorescein dibutyrate (FDB). The reagent fluoresces in the presence of lipases.
In order to make the enzyme activity visible, the kernels are first split in half and coated with the FDB reagent after which they are examined in a suitable measuring device under UV light. An intense yellow fluorescence can be seen in the parts of the kernels where enzyme activity is present.
This method describes how to determine the extract content of malt used to produce laboratory wort.
Malt intended for use in beer brewing or elsewhere in the food industry
The extract content of malt refers to the compounds from finely ground malt (fine grind), which are brought into solution during a standardized mashing process.
The extract content is determined by the weight ratio sL 20/20 of the wort on the basis of the official sugar tables (Plato tables) at 20 °C. sL 20/20 stands for the weight ratio of a volume of wort at 20 °C to the same volume of water at the same temperature.
Malt intended for use in beer brewing or elsewhere in the food industry