Barley intended for the production of malt is evaluated on the basis of germinative capacity.
This method is used to determine the percentage of germination that will occur under normal malting conditions. The germination index provides a good indication of the germination capacity of a barley lot which is no longer dormant [1−3].
The method is based on the BRF/4 ml test with 4 × 100 kernels.
Prediction of the extract content and predetermination of the processability and value of a lot of barley for brewing purposes
The behavior of barley during the malting process, which is intended for large-scale malt production, must be known.
MEBAK approved and adopted a micromalting procedure on 6 April 1971 as a standard method for predicting the extract content and for determining the suitability of barley varieties for malting. In 2003, MEBAK shortened the procedure by one day for a total of six days for vegetative growth (steeping and germination), the same length of time as the EBC procedure.
Potassium permanganate oxidizes many organic and certain inorganic substances more or less completely in acidic, neutral or alkaline solutions. The volume of potassium permanganate required in the analysis is determined potentiometrically. Since oxidation depends on the type of solution, on its temperature and on the reaction time, the procedure described below must be followed precisely.
In acidic solutions, permanganate ions are typically reduced to manganese(II) ions:
MnO4- + 5 e- + 8 H3O+ → Mn2+ + 12 H2O
In alkaline solutions, the reduction results in tetravalent manganese only:
MnO4- + 3 e- + 4 H3O+ → MnO2 + 6 H2O
Since in both cases the titration takes place in an acidic solution, this is irrelevant for the calculation. By adding oxalic acid, both the excess permanganate ions as well as the tetravalent manganese are reduced to manganese(II) ions:
2 MnO4- + 5 C2O42- + 16 H3O+ → 2 Mn2+ + 24 H2O + 10 CO2
MnO2 + C2O42- + 4 H3O+ → Mn2+ + 6 H2O + 2 CO2
This method describes how to determine whether there are pre-germinated kernels in a lot of barley as part of visual and manual inspection processes.
Barley intended for the production of malt; therefore, the kernels are to be evaluated on the basis of the characteristics described below.
Barley is visually inspected for the presence of “open” pre-germination which may be evidence of the presence of “hidden” pre-germination.
This method describes the method for determining the germinative energy of barley by inducing germination in a germination box under defined conditions.
Barley intended for the production of malt is evaluated on the basis of germinative energy.
This method requires that the germination of barley be induced at a defined temperature and humidity. The germination period is three or five days.
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.